Marine parts vs. automotive
MCSERVICE
Electrical components used on marine engines must be Coast Guard
certified. An automotive starter has no spark arresting capability and
could therefore trigger an explosion if there were any gasoline fumes in
the bilge. A marine starter on the other hand must pass the rigerous SAE
J1171 test which in essence means it must be able to withstand multiple
engagements while sealed in a box that also contains an explosive mixture
without exploding the mixture. Other marine electrical components like
alternators, distributors, sloenoids, relays, switches, etc must be able
to pass the same type of test.
Pay the extra money for a certified marine starter or you are putting
yourself, your family/friends and other boaters in extreme danger.
Larry Engelbert
Director of MerCruiser Service
mcse...@aol.com
Mijoy
Anyone with some real insight to the difference between
marine parts such as a starter and an automotive one. I have
been told the difference is safety (less likely to spark).
Given the difference in price, is the marine part really
necessary or is someone just trying to take my money again.
Thanks, Mike
Laxlt
There are a lot of differences in the electrical and fuel system
components. Don't fool around here. Check out some of the marine
discounters. They can come pretty close to the automotive prices for the
right stuff.
Overtons - starters ($100.00 rblt.), exhaust manifolds, distributors and
tune up stuff
J. C. Whitney, Chicago - alternators, fuel pumps
Doug Russel Marine Engines- (508) 791-4917
Boat U.S. - has special engine parts hotline.
Jim Swist
Electrical is the major area where you need marine-grade.
Some things that I can think of that are the same marine/non-marine
and you may be better off at a hardware store or auto parts place:
- Common hardware (a well-stocked hardware store will have stainless
steel nuts/bolts/etc)
- Cleaners/waxes/solvents/antifreeze/grease/etc
- starting batteries (many auto parts stores carry marine starting
batts)
- trailer h/w and associated stuff (a camping/RV store is a good
source for this stuff).
- galley items (some are marine unique like s/s goblets etc but most
can be gotten cheaper in any housewares place).
Wallace Venable
> Anyone with some real insight to the difference between
>marine parts such as a starter and an automotive one. I have
>been told the difference is safety (less likely to spark).
In some cases, the marine version is made from different, more
corrosion resistant materials. In other cases, the part is partially or
totally sealed.
Marine mechanical fuel pumps are sealed to prevent gasoline from
flowing into the bilge in case of a diaphram failure.
Marine starters have screens over the ventilation openings for
"spark suppression."
> Given the difference in price, is the marine part really
>necessary or is someone just trying to take my money again.
In many cases, yes, it is necessary for safety and to satisfy USCG
regulations. Don't make a substitution unless you really know what you are
doing.
Lawrence
In article <504gg6$h...@steadfast.teradyne.com>, Mijoy says...
>
>
> Anyone with some real insight to the difference between
>marine parts such as a starter and an automotive one. I have
>been told the difference is safety (less likely to spark).
>necessary or is someone just trying to take my money again.
>
one down. My understanding is that openings are screened on
some of the electrical stuff so that if it ignites a fire inside
it can't get out. Since there are no exposed holes in most
starters I'm not sure what is screened? The cost difference is
not much so you could go for a rebuilt. Or you could rebuild
it yourself.
You could tear it down and see, I'd sure like to know. I tore
down a 5.7 magnum merc block a couple weeks ago and guess what.
Every part in it had a GM part number on it. Less anyone jump
in, they were not heavy duty parts either.
Like any other regulatory issue some percentage is legitimate
and the rest is just making you pay more. The problem is figuring
out which part is which. Since safty is involved that makes
mistakes a liiiiittle more costly. Buy the rebuilt and grumble!
Lawrence.......
Brent E. Shelley
In article <504gg6$h...@steadfast.teradyne.com>,
Mijoy <michael....@teradyne.com> wrote:
>
> Anyone with some real insight to the difference between
>marine parts such as a starter and an automotive one. I have
>been told the difference is safety (less likely to spark).
> Given the difference in price, is the marine part really
>necessary or is someone just trying to take my money again.
>
>
My experience:
last year I bought a 1973 21' Sea Star cuddy with a Merc 188 I/O. (This
is a Ford 302.) Previous owner told me that all it needed was a new
starter. I thought, "No problem!" I went through 3 [sic] starters in 1
1/2 months. I was able to exchange them without any problem, but to be
towed from the middle of the lake was pretty annoying. Finally I bit the
bullet and dropped $120 into a marine starter and "eating" the $33 for
the automotive. A year later I'm still going strong.
I can't explain why. All I know is that it worked for me. Just
remember, the most odd thing any person can do is to take an internal
combustion engine and stick it in the water. That's how I rationalized
it. :)
Brent
--
+ Brent E. Shelley \ There's nothing more pathetic +
+ Optometry Student \ than a man who denies what +
+ Indiana Univ School of Optometry \ he essentially is. +
Daniel Deitrick
Mijoy <michael....@teradyne.com> wrote in article
<504gg6$h...@steadfast.teradyne.com>...
>
> Anyone with some real insight to the difference between
> marine parts such as a starter and an automotive one. I have
> been told the difference is safety (less likely to spark).
> Given the difference in price, is the marine part really
> necessary or is someone just trying to take my money again.
>
> Thanks, Mike
>
>
BEWARE: MARINE PARTS AND AUTOMOTIVE PARTS ARE NOT COMPATIBLE. And here's
why: An automotive engine is open to the air, a marine engine is not--it's
entirely enclosed. A marine starter is totally enclosed while an
automotive one isn't entirely plugged up. In otherwords, the spark in an
automotive starter is exposed to the air. Unless you want to send your
marine engine sky high, I wouldn't suggest interchanging them.
Even though you may have a 302 Ford engine (as I do) it is modified so
everything is enclosed within itself instead of open to the air as a car
engine is.
Daniel Deitrick
hired help at Sportfisherman Service Center
JKidd10570
It depends, what is your life , your friends, relitives and family's lives
worth? What about the lives of those near you when yours explodes and
shrapnel or fire hurts them? Or maybe they will just be seriously hurt and
their family will sue yours. Not to mention the automotive one is not
Coast Gaurd approved and would result in a fine if inspected or that
automotive starters wont last nearly as long because they are not designed
to be used in marine environment.
HIDDA
Mijoy wrote:
>
> Anyone with some real insight to the difference between
> marine parts such as a starter and an automotive one. I have
> been told the difference is safety (less likely to spark).
> Given the difference in price, is the marine part really
> necessary or is someone just trying to take my money again.
>
> Thanks, Mike
If it's a gas engine, it's critical for you to use marine parts.
Starters and alternators are shielded at the brushes. This helps
minimize the risk of an explosion from a spark if there are any
explosive levels of gas in the bilge.
If it's a diesel, then it may not be all that critical. On the other
hand, how can you be sure there will never be any explosive vapors in
the bilge? i.e. propane, methane, oil mist, diesel mist, etc.
Think about it. If your bilge blows up while you're starting the
engine/s, where does that leave you?
If you really want to save some money, alternators and starters are
actually standard car/truck parts without the special shielding. You
can remove the shielding from the original equipment and transfer it to
the replacement. Of course, if you don't know what you're doing, you
shouldn't be doing it. Get a marine mechanic to do it for you.
Rod Mc Innis
Brent E. Shelley (bshe...@ezinfo.ucs.indiana.edu) wrote:
: I went through 3 [sic] starters in 1
: towed from the middle of the lake was pretty annoying. Finally I bit the
: bullet and dropped $120 into a marine starter and "eating" the $33 for
: the automotive. A year later I'm still going strong.
: I can't explain why. All I know is that it worked for me.
I suspect that the real difference was "new" versus "rebuilt". Some
of the rebuilt parts are real pieces of junk. If you have a difficult
starting engine (or perhaps the battery cables are rather long, or the
flywheel is a little worn, or contacts are a little corroded, ....)
then the rebuilt units may not be up to the task.
Sometimes I think that the "marine" designation is a bit of an
overkill. But the two parts that I would recommend keeping marine
over all other are the starter and fuel pump.
The starter because is sits in the lowest part of the engine
compartment, where the gas fumes will collect. It also tends to make
the most amount of sparking. In addition, the starter is activated
when the boat has been sitting still, which will allow the fumes to
settle very nicely. If anything will touch off an explosion, it will
be the starter.
The fuel pump because this is a very likely source of pumping fuel
into the bilge. The standard fuel pump has a diaphraghm that has fuel
on one side and air on the other. If the diaphraghm ruptures, you get
fuel leaking into the air, which means into the bilge. A failed fuel
pump can pump gallons of fuel into the "air space" in very short
order.
A marine fuel pump has TWO diaphraghms. The bottom diaphragm has
fuel on one side, and a middle chamber on the other. The top
diaphragm separates the middle chamber from the air. A vent line
connects the middle chamber up to the carburator, where any fumes that
leak through will be burned. I have always assumed that a ruptured
diaphragm will cause the engine to flood.....
The alternator and distributer create sparks as well, although not
nearly to the extent that the starter does, plus they are higher up.
To keep your boat "legal" and safe, replace USCG approved parts with
same.
Rod McInnis
Dave Brown
-> The room fell silent as rmci...@adobe.com whispered to All...
Well Rod, let's review a few of your posts, shall we?
rm> Subject: Re: How do I tune Evinrude 35hp?
rm> The first thing you want to do is check the points. (aw, heck, if
rm> your doing that much work, just replace them!).
The first thing you want to do is find out what the hell your talking about.
If this engine is 1977 or newer (and the original post said it was) then it
has electronic ignition and you've needlessly sent someone looking for
something that isn't there with a good possibility he'll screw something up
in the process.
rm> The points are under the flywheel, which means that you need to get
rm> the flywheel off, which generally means a puller of some sort. The
rm> good news is that the flywheel is made to come off and the cheap
rm> pullers generally work OK.
Actually, the flywheel is made to stay on. Having it come off would defeat
the purpose of having it there.
rm> Once you are sure that timing, points and plugs are OK,
Well that's pretty easy advice -- check it how, to what spec, what do bad
points look like? <sigh> Why not have him 'check the port timing' while he's
at it?
rm> I'm not sure that I do it right, but I have always set the high speed
rm> mixture at a fairly nominal throttle setting and under load.
If your not sure you do it right, why on earth would you advise someone else
to follow your lead? Furthermore, this engine has no adjustable high speed
jet and thus once again you have sent a novice looking for something that
isn't there.
rm> Get a good carburator
rm> cleaner solution (warning, be careful where you spill this gunk!) and
rm> clean it up real good. This should help things out a lot.
This should screw his carb royally and I'm surprised your's is still working.
OMC seals the aluminum carb bodies to prevent air leakage through porosity.
Any submersion in a strong carb cleaner will remove this sealant and cause
erratic operation. Once again your well intentioned advice may do more harm
than good.
rm> Subject: Re: Marine parts vs. automotive
rm> Sometimes I think that the "marine" designation is a bit of an
rm> overkill. But the two parts that I would recommend keeping marine
rm> over all other are the starter and fuel pump.
Is it your intention to kill people? There is NO OVERKILL in USCG specs for
marine engines. Every spec has a purpose that is valid and needed.
rm> The starter because is sits in the lowest part of the engine
rm> compartment, where the gas fumes will collect. It also tends to make
rm> the most amount of sparking.
Clearly, you have no idea what goes on inside a distributor then.
rm> In addition, the starter is activated
rm> when the boat has been sitting still, which will allow the fumes to
rm> settle very nicely. If anything will touch off an explosion, it will
rm> be the starter.
More piffle.
rm> A marine fuel pump has TWO diaphraghms. The bottom diaphragm has
rm> fuel on one side, and a middle chamber on the other. The top
rm> diaphragm separates the middle chamber from the air. A vent line
rm> connects the middle chamber up to the carburator, where any fumes that
rm> leak through will be burned. I have always assumed that a ruptured
rm> diaphragm will cause the engine to flood.....
Where do you get your info? A marine fuel pump has no more diaphragms than
an automotive one -- it simply does not vent the diaphragm to the air. As
well, a ruptured diaphragm WILL cause the engine to flood thus telling you
to get your pump serviced.
rm> The alternator and distributer create sparks as well, although not
rm> nearly to the extent that the starter does, plus they are higher up.
On a hot day, the fumes will be continuously rise through convection. There
is no 'safe' place in an engine compartment when fumes are present.
rm> To keep your boat "legal" and safe, replace USCG approved parts with
rm> same.
Amen.
Subj: Re: Outboard motor leaks fuel when tilted
rm> : Whatever any of the mechanic wannabe's say in here -- THIS IS
rm> NORMAL!!!! When : you think about how a carb works, what else could it
rm> do? You have a float : which operates a needle and seat which fills a
rm> bowl with gas. This bowl is : (and must be) vented through an
rm> atmospheric vent. Tip this set-up on it's end : and it's gonna spew gas
rm> -- period.
rm> It doesn't have to be that way.
Never said it did. They could come up with an elaborate series of check balls
if they wanted to, but since nome of them do, your point is moot.
rm> The carburator could be designed such that the vent line was
rm> routed to the back of the carburator, as would the feed line to the
rm> main and idle jets. Tipping the engine to the normal "up" position
rm> would not allow any gas to escape, as the vent and jet lines are still
rm> in the highest portion of the carburetor.
What if the motor fell to the side while tilted up? Same problem.
rm> All the small outboards I have dealt with have never spilled gas
rm> when tipped up, and I tip mine up all the time (a dozen times a day).
rm> If mine spilled a noticeable amount of gas under normal use, I would
rm> certainly want to have it changed.
And since yours might have a breather designed to collect the fuel while in
the tilted position you would never know. <shrug>
In conclusion Rod, the advice you handed out today was better left unsaid.
Your right to have an opinion does not supersede your responsibility to know
what your talking about before you speak.
Yes I've had a bad day......
Regards
Dave Brown
Brown's Marina
... Two most common elements in the universe: Hydrogen & Stupidity.
--
|
| Standard disclaimer: The views of this user are strictly his own.
1329C1000-Garry Heon(MT4084)NOBIN
In article <322BFE...@mauigateway.com>,
HIDDA <denn...@mauigateway.com> wrote:
>Mijoy wrote:
>>
>> Anyone with some real insight to the difference between
>> marine parts such as a starter and an automotive one. I have
>> been told the difference is safety (less likely to spark).
>> Given the difference in price, is the marine part really
>> necessary or is someone just trying to take my money again.
>>
>> Thanks, Mike
>
>If it's a gas engine, it's critical for you to use marine parts.
>Starters and alternators are shielded at the brushes. This helps
>minimize the risk of an explosion from a spark if there are any
>explosive levels of gas in the bilge.
Well I wouldn't say all marine parts. Electrically yes, absolutely, no
question, USCG marine approved, add the fuel pump to the list. Things
like exhaust manifolds and head gaskets you also need marine versions.
But all the internals, intake and carb can be automotive. Before everyone
jumps on me for the carb, you do need to add a set of J tubes to the carb
so any slosh in the bowls gets dumped directly into the intake. I should
also say my only experience has been with Holleys. J tubes are not an
easy item to find. With the help of the folks here in rec.boats I was able
to find a shop that would sell them.
Garry Heon
First Stepp
ga...@holly.mt.lucent.com
My Opinions....Lucent's Network.
bill...@orbiter.com
ga...@holly.ho.att.com wrote:
>
> But all the internals, intake and carb can be automotive. Before everyone
> jumps on me for the carb, you do need to add a set of J tubes to the carb
> so any slosh in the bowls gets dumped directly into the intake. I should
> also say my only experience has been with Holleys. J tubes are not an
> easy item to find. With the help of the folks here in rec.boats I was able
> to find a shop that would sell them.
>
> Garry Heon
> First Stepp
> ga...@holly.mt.lucent.com
> My Opinions....Lucent's Network.
Garry
Please don't offer suggestions that could cause someone injury or death
because of ignorance. A marine carb is more than just a J tube on a car
carb; Holley or any other brand.
Some auto carbs have vents and passageways to the atmophere that can
allow gas fumes to build up in a boat. Some Holleys have a lever and a
cap that opens up the top of the float bowl when the throttle is opened.
Coast Guard specs also call for special fuel line and fittings from the
pump to the carb and also specify that all fuel components (including
rubber and plastic parts) pass a 5 minute burn test without spilling
fuel.
As a warning to people reading these posts, please talk to a qualified
marine professional before trying any ideas that affect the safety of
your boat and the safety of your loved ones. Too many opinions in this
forum are downright unsafe and could lead to a negligence lawsuit. There
are many regulations and standard procedures concerning boats. Contact
the American Boat and Yachting Council for a copy of safety procedures.
I will now step off my soapbox and ask you all to be careful.
--
Bill Grannis, service manager
Bluewater Boats Inc.
Daytona, Florida
--
** Orbiter Online -- Orbiter.Com -- http://WWW.Orbiter.Com
HIDDA
Rod Mc Innis wrote:
>
> Brent E. Shelley (bshe...@ezinfo.ucs.indiana.edu) wrote:
> : I went through 3 [sic] starters in 1
> : 1/2 months. I was able to exchange them without any problem, but to be
> : towed from the middle of the lake was pretty annoying. Finally I bit the
> : bullet and dropped $120 into a marine starter and "eating" the $33 for
> : the automotive. A year later I'm still going strong.
>
> : I can't explain why. All I know is that it worked for me.
>
> I suspect that the real difference was "new" versus "rebuilt". Some
> of the rebuilt parts are real pieces of junk. If you have a difficult
> starting engine (or perhaps the battery cables are rather long, or the
> flywheel is a little worn, or contacts are a little corroded, ....)
> then the rebuilt units may not be up to the task.
>
>
> when the boat has been sitting still, which will allow the fumes to
>
> The fuel pump because this is a very likely source of pumping fuel
> into the bilge. The standard fuel pump has a diaphraghm that has fuel
> on one side and air on the other. If the diaphraghm ruptures, you get
> fuel leaking into the air, which means into the bilge. A failed fuel
> pump can pump gallons of fuel into the "air space" in very short
> order.
>
>
>
> Rod McInnis
The last line says it all.
Rod Mc Innis
Dave Brown (Dave....@typecast.crp.kingston.on.ca) wrote:
: -> The room fell silent as rmci...@adobe.com whispered to All...
: Well Rod, let's review a few of your posts, shall we?
All right. I don't know what side of the bed you woke up on, but
lets continue.
: The first thing you want to do is find out what the hell your talking about.
: If this engine is 1977 or newer (and the original post said it was) then it
: has electronic ignition and you've needlessly sent someone looking for
: something that isn't there with a good possibility he'll screw something up
: in the process.
OK, I can't speak from experience regarding the exact engine in
question. Perhaps you could provide additional information. You
certainly can't mean that ALL outboards have had electronic ignition
since 1977.
: Actually, the flywheel is made to stay on. Having it come off would defeat
: the purpose of having it there.
Some things are made to never come apart. Some things are made with
the expectation that someone may someday need to get it apart again.
On many outboards, there are vital parts located under the flywheel.
Since you may need to get to them, they make it so that it is not too
difficult to get the flywheel off. In general, this means threaded
holes in a reinforced section of the flywheel intended for attaching a
puller. Making it so that it can come off does not "defeat the
purpose of having it".
: rm> Once you are sure that timing, points and plugs are OK,
: Well that's pretty easy advice -- check it how, to what spec, what do bad
: points look like? <sigh> Why not have him 'check the port timing' while he's
: at it?
Well, I did suggest that he just replace the stupid things, and then
he wouldn't have to worry about what "good" or "bad" points looked
like. And if I recall correctly, I also suggested getting the shop
manual, which would tell him what the gap and/or timing should be set
to.
: Furthermore, this engine has no adjustable high speed
: jet and thus once again you have sent a novice looking for something that
: isn't there.
OK, you obviously know this year motor better than I do. The 35 Hp
Evinrude I had did have a high speed adjustment, as well as points.
: This should screw his carb royally and I'm surprised your's is still working.
: OMC seals the aluminum carb bodies to prevent air leakage through porosity.
: Any submersion in a strong carb cleaner will remove this sealant and cause
: erratic operation. Once again your well intentioned advice may do more harm
: than good.
OK, a simple correction would have been in order. If, in their
infinate wisdom, OMC has decided to make it so that you can't clean
the carburetor, then I wouldn't suggest trying to do it. However, it
seems rather wasteful to require replacing the entire carburetor if is
should get gunked up or the seals dried out.
: rm> Subject: Re: Marine parts vs. automotive
: rm> Sometimes I think that the "marine" designation is a bit of an
: rm> overkill. But the two parts that I would recommend keeping marine
: rm> over all other are the starter and fuel pump.
: Is it your intention to kill people? There is NO OVERKILL in USCG specs for
: marine engines. Every spec has a purpose that is valid and needed.
You are stating your *opinion*, not fact. I clearly stated that my
words were a personal opinion.
: rm> The starter because is sits in the lowest part of the engine
: rm> compartment, where the gas fumes will collect. It also tends to make
: rm> the most amount of sparking.
: Clearly, you have no idea what goes on inside a distributor then.
Oh, I know full well what happens in a distributor. But I have
never seen one that was located as low as the starter, nor have I seen
one that had an opening large enough to support a flame path.
For the other readers who might be attempting to follow along, I
would like to point out that Dave has combined more than one of my
posts, and has presented my statements out of context.
These last two quotes of mine were in response to someone who just
experinced a small boat catching fire on them, and are now trying to
establish what parts they should be wary of in looking for another
"used" boat.
My statements indicated that the starter, alternator, and fuel pump
were of the most concern because these are normal "wear and tear"
items, and were likely to be replaced on 15 to 20 year old boat. Very
few people ever have need of replacing their distributor.
: rm> A marine fuel pump has TWO diaphraghms. The bottom diaphragm has
: Where do you get your info? A marine fuel pump has no more diaphragms than
: an automotive one -- it simply does not vent the diaphragm to the air.
Dave, where do you get YOUR information? You are wrong on this one.
Rod McInnis
Laxlt
Before you take Mr. McInnis' word for it, check out his response to a
leaking gas tank on this newsgroup. This place attracts all kinds.
Lawrence
In article <842054...@BBS.Orbiter.Com>, bill...@orbiter.com says...
>
>
>ga...@holly.ho.att.com wrote:
>>
>
>> But all the internals, intake and carb can be automotive. Before everyone
>> jumps on me for the carb, you do need to add a set of J tubes to the carb
>> so any slosh in the bowls gets dumped directly into the intake. I should
>> also say my only experience has been with Holleys. J tubes are not an
>> easy item to find. With the help of the folks here in rec.boats I was able
>> to find a shop that would sell them.
>>
which automotive ones do not. The cost difference is only $100 and the marine
carb comes with an electric choke which the automotive equal has to have added
for an extra $45. Summit carrys marine holleys and eldebrocks. I compromised
and went with an automotive intake and a holley marine carb.
Lawrence......
Lawrence
In article <372_960...@edge.crp.kingston.on.ca>, Dave....@typecast.crp.kingston.on.ca says...
>
<snip>
> rm> Get a good carburator
> rm> cleaner solution (warning, be careful where you spill this gunk!) and
> rm> clean it up real good. This should help things out a lot.
>
>This should screw his carb royally and I'm surprised your's is still working.
>OMC seals the aluminum carb bodies to prevent air leakage through porosity.
>Any submersion in a strong carb cleaner will remove this sealant and cause
>erratic operation. Once again your well intentioned advice may do more harm
>than good.
>
problem. Even if it did how much air do you think would get through????
> rm> Subject: Re: Marine parts vs. automotive
>
> rm> Sometimes I think that the "marine" designation is a bit of an
> rm> overkill. But the two parts that I would recommend keeping marine
> rm> over all other are the starter and fuel pump.
>
>Is it your intention to kill people? There is NO OVERKILL in USCG specs for
>marine engines. Every spec has a purpose that is valid and needed.
>
Some of them are just automotive parts that have been tested. There is no
design change.
> rm> The starter because is sits in the lowest part of the engine
> rm> compartment, where the gas fumes will collect. It also tends to make
> rm> the most amount of sparking.
>
>Clearly, you have no idea what goes on inside a distributor then.
Yes and in both marine and automotive distributors sparks jump from the rotor
to the cap. No amount of 'marinizing' is going to change that.
> rm> A marine fuel pump has TWO diaphraghms. The bottom diaphragm has
> rm> fuel on one side, and a middle chamber on the other. The top
> rm> diaphragm separates the middle chamber from the air. A vent line
> rm> connects the middle chamber up to the carburator, where any fumes that
> rm> leak through will be burned. I have always assumed that a ruptured
> rm> diaphragm will cause the engine to flood.....
>
>Where do you get your info? A marine fuel pump has no more diaphragms than
>an automotive one -- it simply does not vent the diaphragm to the air. As
>well, a ruptured diaphragm WILL cause the engine to flood thus telling you
>to get your pump serviced.
>
You're both right. There are double and single diaphram fuel pumps. I think
the double was abandonded because nobody noticed when the first diaphram
ruptured so what point was there. Both have a vent tube for a hose to the
carb.
<snip>
> rm> : Whatever any of the mechanic wannabe's say in here -- THIS IS
> rm> NORMAL!!!! When : you think about how a carb works, what else could it
> rm> do? You have a float : which operates a needle and seat which fills a
> rm> bowl with gas. This bowl is : (and must be) vented through an
> rm> atmospheric vent. Tip this set-up on it's end : and it's gonna spew gas
> rm> -- period.
>
> rm> It doesn't have to be that way.
>
>Never said it did. They could come up with an elaborate series of check balls
>if they wanted to, but since nome of them do, your point is moot.
>
All carbs marine and automotive vent to the atmosphere. Marine have j-tubes
instead of straight tubes. Some and only some automotive carbs have other
diaphrams that vent the back side to the atmosphere, if they ruptured you'd
have a problem. Marine carbs don't.
Lawrence..........
bill...@orbiter.com
> : Furthermore, this engine has no adjustable high speed
> : jet and thus once again you have sent a novice looking for something that
> : isn't there.
>
> OK, you obviously know this year motor better than I do. The 35 Hp
> Evinrude I had did have a high speed adjustment, as well as points.
Rod,
Your 35 with an adjustable high speed jet was only made in 1958 and
1959. It bears no resemblance to the ignition system, fuel system, or
powerhead design of a 1977 or later 35 as mentioned in the previous
post.
> : This should screw his carb royally and I'm surprised your's is still working.
> : OMC seals the aluminum carb bodies to prevent air leakage through porosity.
> : Any submersion in a strong carb cleaner will remove this sealant and cause
> : erratic operation. Once again your well intentioned advice may do more harm
> : than good.
>
> OK, a simple correction would have been in order. If, in their
> infinate wisdom, OMC has decided to make it so that you can't clean
> the carburetor, then I wouldn't suggest trying to do it. However, it
> seems rather wasteful to require replacing the entire carburetor if is
> should get gunked up or the seals dried out.
I think you went off the deep end here, Rod. Many carbs use a sealing
process. Rochester Carbs, both automotive and marine, in their service
manuals warn against using strong immersion type cleaners.
The best carb cleaner is a foaming carbon cleaner such as OMC's Engine
Tuner. Spray the cleaner in the passageways, jets, float bowl, etc. and
let it soak a few hours. It even will disolve hardened fuel deposits
without ruining the carb. Gumout Choke and Carb Cleaner spray works OK
for light cleaning.
> : rm> A marine fuel pump has TWO diaphraghms. The bottom diaphragm has
>
> : Where do you get your info? A marine fuel pump has no more diaphragms than
> : an automotive one -- it simply does not vent the diaphragm to the air.
>
> Dave, where do you get YOUR information? You are wrong on this one.
Years ago some pumps had dual diaphrams with a sight glass between them
to indicate a leak. Most engines use a single diaphram pump with a
sealed actuator arm with a separate fuel line to the flame arrestor or a
carb fitting. In case of a diaphram rupture, the fuel will not pour into
the crankcase but will flow up the line and dump into the intake
manifold thru either the carb fitting or flame arrestor.
Rod Mc Innis
Lawrence wrote:
: Yes and in both marine and automotive distributors sparks jump from the rotor
: to the cap. No amount of 'marinizing' is going to change that.
You can't stop the creation of "sparks" in places like commutated
motors and the points of distributors. The modification to make them
marine is to prevent this arcing from igniting anything outside of the
motor/distributor.
The modification is NOT to seal the unit. An attempt to seal a
motor or alternator would certainly lead to overheating. Sealing a
distributor will lead to the internal buildup of ozone, which will
have very detrimental effects on the high voltage distribution (long
story behind how this piece of information was learned.....)
The modification is generally a small screen placed over the openings
of the device. Air and fuel vapors can still get inside. The arc may
still ignite them. But the "fire" will be contained to the inside of
the motor/alternator/distributer, and without a continuous feed, will
quickly die.
The flame will NOT travel out through the screen, as it lacks
sufficient energy to heat the screen up to a high enough point to
support combustion. This is the basis of a flame arrestor.
: > rm> A marine fuel pump has TWO diaphraghms. The bottom diaphragm has
: > rm> fuel on one side, and a middle chamber on the other. The top
: > rm> diaphragm separates the middle chamber from the air. A vent line
: > rm> connects the middle chamber up to the carburator, where any fumes that
: > rm> leak through will be burned. I have always assumed that a ruptured
: > rm> diaphragm will cause the engine to flood.....
: >
: >Where do you get your info? A marine fuel pump has no more diaphragms than
: >
: You're both right. There are double and single diaphram fuel pumps. I think
: the double was abandonded because nobody noticed when the first diaphram
: ruptured so what point was there. Both have a vent tube for a hose to the
: carb.
I can't say what is standard today. I have seem some boats with
electric fuel pumps, which could have thier pump chambers sealed from
the atmosphere.
But the engine driven fuel pumps that I have seen all have dual
diaphragms. There is a small hose fitting located between the
diaphragm, which connects up to the carburetor. Most installations I
have seen use a clear vinyl hose for this connection so that you can
see if anything is inside it.
If the diaphragm on the fuel side ruptures first, then you will get
fuel in this hose that leads to the carburetor. If the leak is small,
you might continue to run, but a visual inspection would be able to
notice the liquid in the vinyl tube. A major leak, on the other hand,
would send so much fuel up to the intake of the carburator that I
would expect it to flood out.
If the second diaphragm should fail first, it is not clear to me if
if would be noticable. I suspect that it would depend on the specific
engine.
Many engines have the fuel pump bolting onto the side of the engine
where the interior air space is saturated with oil vapor. If the
second diaphargm ruptured, I would suspect that the air flow from the
crankcase, through the ruptured diaphragm, and up to the carburetor
would leave oil residue in the clear vinyl tube.
Thus, if you see ANYTHING in that tube connecting the inner diagpraghm
space to the carburetor, then you know that you have a problem.
: All carbs marine and automotive vent to the atmosphere. Marine have j-tubes
: instead of straight tubes. Some and only some automotive carbs have other
: diaphrams that vent the back side to the atmosphere, if they ruptured you'd
: have a problem. Marine carbs don't.
I would like to point out that my comments on the carburator, which
had been taken out of context, dealt specifically with an outboard and
the ability for the outboard to tilt up into the full up position
without spilling gas.
You are not going to find too many automotive carburetors on
outboards, so drawing comparisons to them is not really relevent to
the discussion.
To be honest, I never was sure what the significant difference
between the marine and automotive carburetors were. All carburetors
that I have dealt with have their float bowl vents located in the
throttle body, generally via a straight tube extending up above the
choke plate.
If this is what you call a "straight tube", OK, fine. But I am
still not sure what a "J tube" replacement does to improve the safety.
I have also noticed, on a far too small a sample to draw a reliable
conclusion, that *some* marine carburetors don't have external drains
for the float bowls. Is this true of all marine carburetors? If so,
I could imagine that the USCG figured that they didn't want people
draining gas onto their engines while they diagnosed their problems.
Rod McInnis
Peggie Hall
When it comes any part which has to do with either electrical or
fuel systems ANYwhere on the boat, do not use anything but marine!
Example:
A houseboat owner on a local lake came aboard his boat one Friday
afternoon last spring, & the first thing he did was turn on his
air-conditioning. The connection in the bilge had been replaced
with a household switch. There were gas fumes in the bilge. The
resulting explosion & fire destroyed the entire dock and 27 boats
that were in their slips...a dozen others were damaged.
Marine electrical parts are "ignition protected"--meaning a spark
cannot ignite vapors. Marine fuel system parts are modified to
either contain gas spills (for instance a failed fuel pump dumps
gas into the crankcase instead of the bilge) or prevent vapors
from igniting.
NEVER substitute unless you know for absolute certain that there
is no difference between a marine and an automotive or
household part!
Peggie Hall/Peal Products
Specializing in marine sanitation since 1987 (but a longtime boat
owner too)
Rod Mc Innis
bill...@orbiter.com wrote:
: > : rm> A marine fuel pump has TWO diaphraghms. The bottom diaphragm has
: >
: Years ago some pumps had dual diaphrams with a sight glass between them
: to indicate a leak. Most engines use a single diaphram pump with a
: sealed actuator arm with a separate fuel line to the flame arrestor or a
: carb fitting. In case of a diaphram rupture, the fuel will not pour into
: the crankcase but will flow up the line and dump into the intake
: manifold thru either the carb fitting or flame arrestor.
: --
: Bill Grannis, service manager
Bill, can you tell me how the actuator arm is sealed without the use
of a diaphragm?
It is fairly easy to seal rotating shaft using a spring tensioned
rubber seal.
A reciprocating motion, such as a push rod through a guide, is a
little harder, but a fairly effective seal can still be made. They
tend to not last as long, however.
But the mechanicl action of the fuel pump is more of a lever action.
Its rather complex motion can not be sealed the same way that a
rotating shaft is.
Keep in mind that we are talking about a fuel pump that is
essentially the same as the autmotive equivalent. A motor that was
originally designed for marine use would have the opportunity to
design the fuel pump such that an appropriate seal could be made.
But the point of the discussion was automotive versus marine. The
marine fuel pump has to bolt onto the same place that the automotive
fuel pump does, and operate the same way.
The only way that I have seen to seal this complex motion of the
actuating lever is to use a diaphragm. It is actually fairly trivial.
In your post, you made a distintion between a "dual diaphragm" pump
and a "sealed actuator arm". I submit that they are one in the same
beast.
Rod McInnis
Dave Brown
-> The room fell silent as Lawrence whispered to All...
DB> OMC seals the aluminum carb bodies to prevent air leakage through
DB> porosity. Any submersion in a strong carb cleaner will remove this
DB> sealant and cause erratic operation. Once again your well intentioned
DB> advice may do more harm than good.
La> Actually that's corrosion protection, cast aluminum doesn't have a
La> porosity problem.
Actually, it's a sealant. We have covered this problem extensively at OMC
service school and I have personally diagnosed and replaced three carbs with
porosity problems in the last ten years. For what it's worth, I have also
replaced a Mikuni carb on a Ski-Doo with the same problem.
La> Even if it did how much air do you think would get through????
Enough to make it idle like a bag of dirt and bog on take-off. It takes very
little to upset an outboard's idle.
La> Some of them are just automotive parts that have been tested. There
La> is no design change.
Untrue again. The USCG designation means that it has been marinized in some
way. It may be durability, corrosion resistance, ignition protection or
whatever, but it *is* different.
DB> Clearly, you have no idea what goes on inside a distributor then.
La> Yes and in both marine and automotive distributors sparks jump from
La> the rotor to the cap. No amount of 'marinizing' is going to change
La> that.
But it's what a marinized distributor does to contain the spark. <sigh>
DB> Where do you get your info? A marine fuel pump has no more diaphragms
DB> than an automotive one -- it simply does not vent the diaphragm to the
DB> air. As well, a ruptured diaphragm WILL cause the engine to flood thus
DB> telling you to get your pump serviced.
La> You're both right. There are double and single diaphragm fuel pumps.
La> I think the double was abandonded because nobody noticed when the first
La> diaphragm ruptured so what point was there.
This is my twentieth year repairing boats and I have yet to see a double
diaphragm fuel pump. If such a beast exists, I'd be interested in hearing
who manufactured it and when.
La> All carbs marine and automotive vent to the atmosphere. Marine have
La> j-tubes instead of straight tubes. Some and only some automotive carbs
La> have other diaphrams that vent the back side to the atmosphere, if
La> they ruptured you'd have a problem. Marine carbs don't.
Once again, it's *how* a marina carb handles the venting, not whether or not
it vents.
Regards,
Dave Brown
... Anything you say will be misquoted and used against you.
Lawrence
> DB> OMC seals the aluminum carb bodies to prevent air leakage through
> DB> porosity. Any submersion in a strong carb cleaner will remove this
> DB> sealant and cause erratic operation. Once again your well intentioned
> DB> advice may do more harm than good.
>
> La> Actually that's corrosion protection, cast aluminum doesn't have a
> La> porosity problem.
>
>Actually, it's a sealant. We have covered this problem extensively at OMC
>service school and I have personally diagnosed and replaced three carbs with
>porosity problems in the last ten years. For what it's worth, I have also
>replaced a Mikuni carb on a Ski-Doo with the same problem.
>
> La> Even if it did how much air do you think would get through????
>
>Enough to make it idle like a bag of dirt and bog on take-off. It takes very
>little to upset an outboard's idle.
>
Sorry I'm not buying that at all. Similar carbs can be found
in the motorcycle world without the sealant. How do they handle air
leakage through the cast aluminum? Your suggesting that cast alluminum
would leak enough air to affect something that's normal air path is
measured in cubic feet per minute. And this leak would occur with
the relatively small pressure differential found in a carb. Even at
idle many cubic feet per minute move through an engine. I'd be more
inclined to believe that soaking the carb had upset an internal seal
and fuel was leaking internally.
Lawrence......
Lawrence
> To be honest, I never was sure what the significant difference
>between the marine and automotive carburetors were. All carburetors
>that I have dealt with have their float bowl vents located in the
>throttle body, generally via a straight tube extending up above the
>choke plate.
>
> If this is what you call a "straight tube", OK, fine. But I am
>still not sure what a "J tube" replacement does to improve the safety.
>
into the throttle. Also vapors are more inclined to do the same. Few
automotive carbs have float drains anymore. On holleys, both marine
and automotive, you will find openings covered by screw-in plugs on the
float bowls which are used to set the float level.
Lawrence.....
Lawrence
To those who are following this thread please don't take any of my
comments to suggest you should use automotive parts instead of marine
parts. If you do not fully understand the engineering differences
between a marine part and an automotive part you should just buy the
marine part and move on.
This thread is almost a constant feature on rec.boats and so many people
have opinions about what the actual differences are. It certainly draws
out interesting discussion on marine engineering. Plus some pretty wild
statements!
Lawrence......
Dave Brown
-> The room fell silent as Lawrence whispered to All...
La> Sorry I'm not buying that at all. Similar carbs can be found
La> in the motorcycle world without the sealant. How do they handle air
La> leakage through the cast aluminum? Your suggesting that cast
La> alluminum would leak enough air to affect something that's normal air
La> path is measured in cubic feet per minute. And this leak would occur
La> with the relatively small pressure differential found in a carb. Even
La> at idle many cubic feet per minute move through an engine. I'd be
La> more inclined to believe that soaking the carb had upset an internal
La> seal and fuel was leaking internally.
I would think you should pass along your thoughts to OMC engineering then.
They've obviously erred and need your wisdom to improve their product. <sigh>
End of thread for me...
Dave Brown
Brown's Marina
Lawrence
> La> Sorry I'm not buying that at all. Similar carbs can be found
> La> in the motorcycle world without the sealant. How do they handle air
> La> leakage through the cast aluminum? Your suggesting that cast
> La> alluminum would leak enough air to affect something that's normal air
> La> path is measured in cubic feet per minute. And this leak would occur
> La> with the relatively small pressure differential found in a carb. Even
> La> at idle many cubic feet per minute move through an engine. I'd be
> La> more inclined to believe that soaking the carb had upset an internal
> La> seal and fuel was leaking internally.
>
>I would think you should pass along your thoughts to OMC engineering then.
>They've obviously erred and need your wisdom to improve their product. <sigh>
>
>End of thread for me...
>
>
> Dave Brown
> Brown's Marina
>
Einstein. I'm not going to believe it if it doesn't make sense without
an explaination. And air leakage through cast alluminum doesn't make
sense.
Lawrence........
middlecoast
Keep in mind there are many different aluminum alloys with varying
properties and porosity. There are also different thicknesses of casting.
An aluminum door is not the same as a carbuetor housing. Guess which one
has the most zinc... Also, heat and expansion affect a casting. Some
carburetors have been known to crack, the hairline crack invisible to the
nake eye. In other words, it's my opinion that the issue is much more
complicated than expressed by some parties in this thread.
Wayne Johnson
Dave....@typecast.crp.kingston.on.ca (Dave Brown) wrote:
>-> The room fell silent as Lawrence whispered to All...
> La> Sorry I'm not buying that at all. Similar carbs can be found
> La> in the motorcycle world without the sealant. How do they handle air
> La> leakage through the cast aluminum? Your suggesting that cast
> La> alluminum would leak enough air to affect something that's normal air
> La> path is measured in cubic feet per minute. And this leak would occur
> La> with the relatively small pressure differential found in a carb. Even
> La> at idle many cubic feet per minute move through an engine. I'd be
> La> more inclined to believe that soaking the carb had upset an internal
> La> seal and fuel was leaking internally.
>I would think you should pass along your thoughts to OMC engineering then.
>They've obviously erred and need your wisdom to improve their product. <sigh>
>End of thread for me...
> Dave Brown
> Brown's Marina
>
>--
>|
>| Standard disclaimer: The views of this user are strictly his own.
I sure hope so.
I used to make quickie vacuum chambers with aluminum doors. Pump that
sucker down to nothing, and hold it there for days.
Not much air leakage.
There's got to be more to it than that.
Wayne Johnson
cia...@ix.netcom.com
"Despite all the implications...you can dance to a rock and roll station..."
Lou Reed, "Rock and Roll"
Lawrence
The original debate is about air leaking through cast alluminum carb
bodies and affecting idle and low rpm. I don't believe it can, coating
or no coating. Cracks are cracks and the carb is junk if it's cracked.
I have never seen a cracked carb body but hey it could happen.
I'm curious what other complications you see? I'll agree that you
could concievably come up with an alluminum alloy that is porous but
why would you then use it to make carburetors?
Lawrence........
Dave Brown
-> The room fell silent as cia...@popd.ix.netcom.com whispered to All...
ci> I sure hope so.
ci> I used to make quickie vacuum chambers with aluminum doors. Pump that
ci> sucker down to nothing, and hold it there for days.
ci> Not much air leakage.
ci> There's got to be more to it than that.
This whole thread borders on the ridiculous. Here you have *all* of the tech
people on line saying that carb porosity is a fact (supported by factory
service), and then you have the tech wanna-bees saying it can't be so. I
personally don't care if you guys believe it or not, and, as stated, I have
actually run into it on brand new products suffering from it (the simple
diagnostic check of pouring gas over the carb body confirms it).
Think about this, if you will, if minor air leakage would have little effect
on the low speed circuits, why is it that drilling out a fixed air bleed in
a carb by as little as .001" will cause the engine to lean spit? .001"!!!!!
*Any* air entering the fuel supply where it wasn't designed to, has enormous
effects on a two stroke engine. If I ever have a vacuum cleaner problem, I'll
call you. If I have a motor problem I can't solve, I'll rely on OMC engineers
thanks.
Regards,
John Jackson
Dave Brown (Dave....@typecast.crp.kingston.on.ca) wrote:
[...]
: This whole thread borders on the ridiculous. Here you have *all* of the tech
: people on line saying that carb porosity is a fact (supported by factory
: service), and then you have the tech wanna-bees saying it can't be so. I
: personally don't care if you guys believe it or not, and, as stated, I have
: actually run into it on brand new products suffering from it (the simple
: diagnostic check of pouring gas over the carb body confirms it).
If someone in the 'factory tech' group of people would be willing to
explain it, I would LOVE to hear a plausible description of how 'porous'
aluminum can allow enough volume of air to pass through it to noticeablely
affect the operation of any engine.
: Think about this, if you will, if minor air leakage would have little effect
: on the low speed circuits, why is it that drilling out a fixed air bleed in
: a carb by as little as .001" will cause the engine to lean spit? .001"!!!!!
What is 'lean spit'? As for .001", I think a good way to look at your
example would be to figure out how much surface area of 'porous' aluminum
it would take to allow an equal amount of air to pass through it as the
.001" change in diameter of an air jet in a carburetor that you spoke of.
Even though .001" sounds like a very tiny amount, I'd still bet good money
that it would take a huge number of square feet of surface area of
'porous' aluminum to allow as much air to pass through it. Definitely many
more square feet than you would have for the total surface area of a
carburetor on any engine. I would be MUCH more willing to bet that the
reason pouring gasoline on the outside of a carburetor temporarily
cleared up your engine's troubles was due to the simple fact that you had
an air leak *someplace* in one of the carburetor's fittings, lines or
gaskets. In such a case pouring gasoline on the offending area would
definitely counteract the air leak to some extent. At such a point, it
doesn't matter what you concluded the problem was. The action to take
would be to take the carburetor off and repair/probably replace it. In
doing so, it's also very believable that the original air leak would be
corrected. I think that 'porous' aluminum is really a catch-all
diagnosis adopted by the 'factory tech' people because it's much easier
to blame something insidious and almost completely umprovable like
that than to have to painstakingly and meticuously track down the cause
of a niggling little air leak someplace in the carburetor assembly.
: *Any* air entering the fuel supply where it wasn't designed to, has enormous
: effects on a two stroke engine. If I ever have a vacuum cleaner problem, I'll
: call you. If I have a motor problem I can't solve, I'll rely on OMC engineers
: thanks.
:
: Regards,
:
: Dave Brown
: Brown's Marina
I never rely on anyone but myself. After all, when it comes to your
success and integrity, who else will have a greater interest in
achieving those things? Just because the factory or the tech people say
so doesn't necessarily make it true.
Lawrence
In article <526ptc$8...@nic.umass.edu>, jo...@asimov.oit.umass.edu says...
Ya gotta love the internet! I have not heard 'all' the tech people siding
with the porous alluminum theory. And as to the tech wanna-bees, true I'm not
nor never was a marine mechanic. However I was an automotive mechanic for 10
years, had enough of that. I never once heard of 'porous' alluminum carbs.
I've worked on just about every internal combustion engine made from chain
saws to cat desiels. I also never poured gasoline on any of them. I spray
carb cleaner and if it changes the idle it is due to a leak somewhere. Try
it instead, the gas pouring sounds a little dangerous. None of the carbs
I've ever seen were coated except marine. And many of those carbs are made
by the same company, marine and non-marine. The coating is simply to prevent
corrosion.
Let's face it, if you had an alluminum alloy that was porous when used for
castings you just wouldn't make carburators out of it. btw Dave I thought
you were not going to respond anymore? The temptation was too great huh?
Later, Lawrence.......