My Mercruiser 5.7L problems
Keith Beckmann
Well, since someone was interested, here goes.
Late in 1995 I bought a new boat. My first new boat, and my first I/O. I
chose a 22' Sea Sprite made at a company near Chicago, powered by a
Mercruiser 5.7L.
I took the boat out on a test drive at the dealer, and it seemed nice.
Top end was around 48MPH @ 4500 RPM and no gear, and only half a tank of
gas. I bought it so late in the year (October 95), that I never had a
nice weekend to get it in the water, but I got such a good deal I figureed
I could wait.
Launched May 22, 1996 and had 20 hours on by June 20th. I babied it for
it's first 20, cause I wanted it to last for a while. It was christened
the "Hassle Too", after my last boat, the "Hassle". It has surpassed it's
name! I slipped it in a river that leads to Lake Michigan, since all I
ever use a boat for is fishing and cruising.
All was well until the first time that Lake Michigan was like glass. Here
was my first chance to actually run the boat at WOT for more than 2
minutes, and outside the breakwater. 15 minutes into my thrill I started
losing RPM, I throttled back, heard a pop, and the engine quit. A few
seconds later the Oil/Temp warning sounded. I was dead in the water!
Luckily, no waves and I was not near anything dangerous. I checked the
oil, looked around the engine. It was getting dark, of course. It seemed
hot, but the temp while it was running never exceeded 180 degrees.
Checked the gas, by giving the carb a pump and it spit into the carb. I
gave the starter a shot and after about 10 minutes she re-started. Took
it nice and easy back to my slip. Next day I called the Marina and setup
an apointment.
They took a week to get to it, and found that the timing was off by 4
degrees and that a manifold bolt was loose. They charged me $50 to re-do
the timing (Which was fine 6 motor hours before at the 20 hour checkup)
and said I should be fine.
Mid-August was the next time the lake was like glass. This time I had the
father-in-law, and brother-in-law along so we could do a little fishing.
The fish had just really started biting, which was late. 15 minutes
outside the breakwater, again at WOT it started losing RPM, I throttled
back, and the motor quit again. I could feel that she was gonna quit
before she did. Oil pressure was normal, and the temperature was at 180
degrees. This time she didn't re-start so easily. I pulled the cover
off, checked the oil level, and could hear boiling water inside the
engine. I pulled the anti-flame arrestor and could smell and see gas
boiling out the top of the carb. I had everyone out away from the engine,
and the fire extinguisher out. I waited a while (again a nice day, no
waves, and out in the middle of no place), and tried starting. No dice.
She turned over, but would not fire. I checked wiring, even pulled a wire
to check for spark. Finally 45 minutes later, after letting it crank for
what seemed way to long, she began to fire, and I got her started.
I reved up a little, but she sounded funny. I put her in gear and she
felt funny. We decided to call it a morning, consider ourselves lucky,
and head in. Next day I called the marina again for an appointment.
She sat there for another week before they looked at her. Again, the
timing was off and they accused me of messing with it!!! They couldn't
find anything else wrong. They tested it (But not a WOT for 15 minutes),
and proclaimed it fixed. I said no way, there's gotta be something more
than just a slight mis-timing. They looked at it some more, replaced the
plugs and said that was all they could do. I said I was not comfortable
with what was happening, and demanded that they at least test it at WOT
for 15 minutes. They said that they would have to charge me $50 per hour
to test it, which I agreed to.
While I was waiting for them to test it, I called Mercruiser (Hey them
carphones come in handy!) I explained what was happening, and they said
the would call the dealer. By the time I walked back to the dealer,
Mercruiser was on the phone with them, authorizing a company-paid sea
test. 1 POINT FOR MERCRUISER!!!
I went out with the mechanic, with him driving and discovered why they
couldn't re-create the problem. He wasn't running it at WOT, because he
was not a boater. After his lame attempts to get it to fail, and my
telling him that he must run it at WOT, otherwise it runs fine, he gave
the helm to me. I ran it at WOT, inside the breakwater, and in 10 minutes
I began losing RPM. He had me throttle down to idle, just as it started,
and pulled the cover off the floor. The engine sounded weird, and the
large hoses by the thermostat were pulsing, as if the pressurizing, and
de-pressurizing. He hadn't seen enough, and had me run it at WOT again.
10 minutes later we were in the same boat (Get it, same boat!!! Ha, at
least I still have a sense of humor). We headed back to the marina.
The mechanic called Mercruiser, and explained what was going on. He
talked to the other mechanics, because he was lost. He had never in his 2
years as a boat mechnic seen anything like this. Someone (Either
Mercruiser or someone else) figured out that the 180 degrees was wrong.
Since it has a 160 degree themostat, mercruiser says it should not go
above 160 degrees, no matter what!
Apparently starting sometime in 1995, Mercruiser Alpha 1's began having a
problem. Now I've heard 2 stories (Well 3, if you count the "There's
nothing wrong").
1) The plate that the impeller in the stern drive sits on, that has a
housing around it that pumps water to the engine warps and allows air to
enter. This creates hot pockets in the engine, and make the water
temperature rise in the engine. This will only happen when the stern
drive is most of the way out of the water, and the engine is running hard
(Read "WOT").
2) The lower part of the stern drive had too much paint applied at the
junction between the lower section of the stern drive and the upper
section of the stern drive, right where the impellor assembly is. This
creates to large of a crack between the two, that air can enter, creating
hot pockets, and so on (see above #1 above).
In my case, the marina decided that they would seal the impeller housing
with RTV sealant. They re-assembled, and supposedly sea-tested (I don't
know how well) and again proclaimed all was fixed. They even said it was
running quite well and maintained 4500 RPM without trimming (An outright
lie!)
I had a misfortune the day before, and sprained both my wrists, bruised a
rib and scraped up one side of my body (Another long story, but off topic,
luckily), so I was unable to pick the boat up. I had my father get it,
and move it to my slip. I took a month to heal before I felt I could even
attempt taking the boat out.
It was of course getting late in our short season, and was a little
windier than I would of liked, and there were actually small craft
advisories out, but then the wind was coming from the west, and I figured
I could stay close to shore, and inside the breakwater. I had to try it
out!!! I was surprised on how nice it was on the lake. Close to shore it
was very nice, and I could run at WOT, outside the breakwater. I ran it
for 25 minutes without it quiting. My RPM's were still down though, only
4000 RPM, but the temperature never exceeded 160 degrees. The problem was
it ran quite a bit rougher than it ever did before. At idle in gear, you
could feel the motor throughout the boat. The next day I called the
marina again, and was told it needed some time to "break in".
I had the opportunity to take it out a couple more times, and it didn't
get any better. By this time it was time to have it taken out, and
winterized. I talked to the marina again, and spoke to their new
service manager, who was interested in my problems.
Originally they were going to just winterize it, and look at it in the
spring, but then decided to look into it deeper. They did a compression
test (Yes, an actual diagnostic test!) and found that the number 4
cylinder had no compression (At least it wasn't my imagination). They had
a rep from Mercruiser come look at it, who decided it needed to be pulled.
They pulled the motor and removed the head from that side. The valve was
bent!! They say due to water being in the cylinder. Best answer I've
heard is that when it quit the last time, it sucked water in that
cylinder. The dealer had requested a long block from Mercruiser, but
Mercruiser decided that since it was just running out of warranty, that
all that should do is have a valve job, and re-assemble it.
Unfortunatly, the last I was informed was that they were waiting for a new
engine, and was never told they were just gonna fix the valve and
re-assemble it. That bring us up to today, where I had to call Mercruiser
again to find out why there not replacing the engine.
I'm under the firm belief that the motor was damaged by whatever was
causing the motor to shut down at WOT. I don't think that a single valve
that was danaged by the shutdown was what was causing the motor to shut
down. I'm not sure that the 180 degrees that the engine was running at
was to hot or not to "cook" the motor. I've been a car mechanic for many
years, and have rebuilt Chevy small block many times.
What do you think??????
---------
Internet: kbec...@earth.execpc.com
kbec...@solaria.sol.net
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Bryon Kass
4 cycle gas engines are not really made to run at 4500rpm for very long.
What you were experiencing with the raw water pump is typical of that
type of system. A better system for hard running is an internal engine
driven pump with a larger capacity, picking up water thru the hull. You
cannot jump waves with such a system as it will airate as well. A raw
water cooled engine has this tendency to suck air and get hot pockets.
The bent valve was probably caused by the hydraulic lock or overheating
in that spot and a valve guide siezing. I hope the cylinder was not
scored as a valve job is insufficient. I would invest in a fresh water
cooling kit. Another problem with air in the block is the reduced
efficiency of the circulator pump (pulsating hoses). All you need is
a few seconds of overheating to cause damage. You may have also
blown the head gasket. The engine shut down from vapor lock or the heat
boiled the gas out of the carbs overflows flooding it and fouling
the plugs. You are lucky the engine has a marine carb or it would have
gone skyward! The timing shift may have been caused by the valve train
tightening up and causing the timing chain to jump a gear. This would
explain the 4 degree shift. The timing cover should be removed and
the chain and gears inspected for the shift and any damage. The gears
are usually plastic! A new all steel gear set is worth the $40.
They are a little noisier but hold together under severe stress.
Good luck!!!
Bryon Kass
webmaster and
Custom Design
150 Mechanic St.
Foxboro, MA 02035
508-543-9068 or fax 508-543-5127
in THE ENGINE ROOM http://www.ici.net/customers/cusdn
Lawrence
In article <56bvkt$7...@bashir.ici.net>, Bryon says...
>
>4 cycle gas engines are not really made to run at 4500rpm for very long.
>What you were experiencing with the raw water pump is typical of that
>type of system. A better system for hard running is an internal engine
>driven pump with a larger capacity, picking up water thru the hull. You
>cannot jump waves with such a system as it will airate as well. A raw
>water cooled engine has this tendency to suck air and get hot pockets.
>The bent valve was probably caused by the hydraulic lock or overheating
>in that spot and a valve guide siezing. I hope the cylinder was not
>scored as a valve job is insufficient. I would invest in a fresh water
>cooling kit. Another problem with air in the block is the reduced
>efficiency of the circulator pump (pulsating hoses). All you need is
>a few seconds of overheating to cause damage. You may have also
>blown the head gasket. The engine shut down from vapor lock or the heat
>boiled the gas out of the carbs overflows flooding it and fouling
>the plugs. You are lucky the engine has a marine carb or it would have
>gone skyward! The timing shift may have been caused by the valve train
>tightening up and causing the timing chain to jump a gear. This would
>explain the 4 degree shift. The timing cover should be removed and
>the chain and gears inspected for the shift and any damage. The gears
>are usually plastic! A new all steel gear set is worth the $40.
>They are a little noisier but hold together under severe stress.
Merc claims that their configurations are tested for several hours at
wot. I would expect it to work. The heat may have caused the valve to
stick and then the piston would have bent it. I would suspect the
whole cylinder. Pistons were not made to bend valves. I guess the
newer 160 thermostats leave less margin for problems than the old 140s.
All in all I would have expected the dealer to figure out the water
supply problem earlier. It's had enough abuse now that I'd want a new
engine.
Lawrence....
george
:4 cycle gas engines are not really made to run at 4500rpm for very long.
I'd be real interested to hear direct from merc if their engines
are not capable of running at the max recommended rpm for even
a few minutes!
--
george
geo...@mech.seas.upenn.edu
george
:Merc claims that their configurations are tested for several hours at
:wot. I would expect it to work.
this is a known problem with the 5.7 /genII alphaI setup.
The symptom is absolutely normal temperature, then 'flash'
overheating so quick it doesn't even register on the gage
before damaging the engine.
Of course they dont tell you about it until you get stuck.
Near as I can tell, the pumps were sealed incorrectly. The
service bulletin just says take apart - reseal - reassemble.
Unfortunately there is no way to know if you have one that
was put together properly until you have a failue either.
--
george
geo...@mech.seas.upenn.edu
Sean Gilboy
Bryon Kass wrote:
>
> 4 cycle gas engines are not really made to run at 4500rpm for very long.
> type of system. A better system for hard running is an internal engine
> driven pump with a larger capacity, picking up water thru the hull. You
> cannot jump waves with such a system as it will airate as well. A raw
> water cooled engine has this tendency to suck air and get hot pockets.
> The bent valve was probably caused by the hydraulic lock or overheating
> in that spot and a valve guide siezing. I hope the cylinder was not
> scored as a valve job is insufficient. I would invest in a fresh water
> cooling kit. Another problem with air in the block is the reduced
> efficiency of the circulator pump (pulsating hoses). All you need is
> a few seconds of overheating to cause damage. You may have also
> blown the head gasket. The engine shut down from vapor lock or the heat
> boiled the gas out of the carbs overflows flooding it and fouling
> the plugs. You are lucky the engine has a marine carb or it would have
> gone skyward! The timing shift may have been caused by the valve train
> tightening up and causing the timing chain to jump a gear. This would
> explain the 4 degree shift. The timing cover should be removed and
> the chain and gears inspected for the shift and any damage. The gears
> are usually plastic! A new all steel gear set is worth the $40.
> They are a little noisier but hold together under severe stress.
> Bryon Kass
> webmaster and
> Custom Design
> 150 Mechanic St.
> Foxboro, MA 02035
> 508-543-9068 or fax 508-543-5127
> in THE ENGINE ROOM http://www.ici.net/customers/cusdn
That's a car engine is not made to run at 4500 very long. This a marine
engine and they do run 4500 all day long bone head.
Lawrence
In article <328A7C...@mail.vbe.com>, Sean says...
>
>Bryon Kass wrote:
>>
>> 4 cycle gas engines are not really made to run at 4500rpm for very long.
>> What you were experiencing with the raw water pump is typical of that
>> type of system. A better system for hard running is an internal engine
>> driven pump with a larger capacity, picking up water thru the hull. You
>
>engine and they do run 4500 all day long bone head.
And just what do you think is different between the 'marine' engine and
the 'car' engine that would have anything to do with it running 4500 rpm
all day? Brass freeze plugs? A vent hose on the fuel pump?
Lawrence....
Sean Gilboy
May be you should educate yourself before you open your mouth.
Lawrence
In article <328BE0...@mail.vbe.com>, Sean says...
Maybe you try supplying facts instead of insults. I've dissassembled merc
5.7 engines. The internal components are identical to the automotive ones.
This discussion has been had before. The crank is cast, the pistons are cast,
the rods are stock. OK, the exhaust valves are stainless. All the internal
components have gm casting numbers on them, even the cam.
Maybe you should try figuring out how this works. Different people voice
opinions. Either they fit or do not fit with your opinions. If they do not
then you can disagree. If you disagree then you may be asked to provide some
facts that support your opinions. Simply making derogatory comments is ok
too. This is electronic anarchy so we all get to do pretty much whatever we
want. Me included. But if you wish others to place 'value' on your opinions
then you're not likely to get very far by simply making derogatory comments.
You could be right, that doesn't matter. What matters is are you believed?
Before you make the standard response 'I don't care....' then why post?
Fact is I agree with the previous poster, running a 'marinized' automotive
engine at or near maximum output for extended durations is inviting problems.
At a minimum it is shortening the useful life.
Later, Lawrence.......
Sean Gilboy
They are designed to run at 4800 rpm that's why it posted if it couldn't
do it why would mercruisier recommend it. Also mercrusier has
enduranced engines at wot for more than 500 hrs so why do you think you
can't run them wot. There's more to marine engines than meet the eye.
Why doesn't gm just make them or why doesn't some big time engine
building shop make them. It more complicated than you a willing to give
any credit for.
jeff...@execpc.com
Lawrence wrote:
>In article <56bvkt$7...@bashir.ici.net>, Bryon says...
>>
>>4 cycle gas engines are not really made to run at 4500rpm for very long.
How about 6 cylinder engines? Can they run at WOT for very long
without causing any damage? Mine is not a Merc but is a 4.3 6.
Jeff Fischer
jeff...@execpc.com
http://www.execpc.com/~jeffishr
West Allis, WI (Near Milwaukee)
'91 18' Thundercraft OMC V-6
1329C1000-Garry_Heon(MT4084)NOBIN
In article <3290F4...@mail.vbe.com>,
Sean Gilboy <se...@mail.vbe.com> wrote:
SNIP for bandwidth
>
>They are designed to run at 4800 rpm that's why it posted if it couldn't
>do it why would mercruisier recommend it. Also mercrusier has
>enduranced engines at wot for more than 500 hrs so why do you think you
>can't run them wot. There's more to marine engines than meet the eye.
>Why doesn't gm just make them or why doesn't some big time engine
>building shop make them. It more complicated than you a willing to give
>any credit for.
First Mercruiser NEVER recommended that you run your engine at WOT all the
time. It's the posted _rated_ WOT rpm range so you can prop the boat
correctly. Failing to prop the boat correctly will cause the engine
to lug (over propped engine can't reach the WOT range) or over rev (under
propped engine spins well over rated WOT range) both causing premature
engine failure. It has absolutelty nothing to do with the recommended
continuous operating rpm.
Having said that......
I'd like to see any marine gas engine run at rated WOT under load for 500
hours. I've been in the high performance end of things for a long time and
have yet to see an engine that's been run hard last 500 hours without a
rebuild. I've seen engines that have been run hard that Merc replaced under
warranty after they died. Even Mercs best engines that come out of Merc's
High Performance division don't last 500 hours run hard. GM does build all the
short blocks for Merc. The only engines (bottom end) that Merc actually builds
are the ones coming from Merc high performance, HP465 through 1000SC. Merc
high performance does an outstanding job on their engines. In fact they were
building some of the Corvette engines for GM. I believe it was the engine GM
co-developed with Lotus. Some car buff will probably know more, I'll stick
with the boats. The rest are short block direct from GM. Marine engines are
really more complicated? I don't think so. Having built high performance
engines for my boat I dodn't really see any big difference. My engines have
been turning 5500 rpm for 200 hours now with no problems. I'm still planning
on freshening them up around the 350 to 400 hour mark. I really
think you should say that marine engines are _different_ than automotive.
An automotive application isn't the best choice for a boat because the
power curve is different. Most automotive mechanics don't know the
correct cam grind for marine engines, not because they more complicated,
just because they're not familer with the application. As far as other
shops building motors (buying the GM short blocks), there are a few big names
like Marine Power and Crusader (sorry I don't know alot of the pleasure names).
For the high performance guy, generally the one who will pay $20K to $30K for
an engine there are alot of builders, too many to even begin mentioning, but
if you would like a list take a look at the Offshore Powerboat Racing page and
browse through the Teams to see who's building the power. Most boats are
running with names other than the big ones.
I'd be interested in what you believe to be more complicated about a marine
engine. If you'd like I could email you the complete build sheet for my
engines including parts, balance weights and clearences. Nothing magical
about them, other than the magic that came out of the brain of the builder
(Teague) that recommended the combination of parts suitable for my application
(HP, RPM, Reliability). Bob's the BEST.
Garry Heon
First Stepp
ga...@holly.mt.lucent.com
My Opinions....Lucent's Network.
Lawrence
In article <56seqq$r...@newsops.execpc.com>, jeff...@execpc.com says...
>
>Lawrence wrote:
>
>>In article <56bvkt$7...@bashir.ici.net>, Bryon says...
>>>
>>>4 cycle gas engines are not really made to run at 4500rpm for very long.
>
>How about 6 cylinder engines? Can they run at WOT for very long
>without causing any damage? Mine is not a Merc but is a 4.3 6.
>
they say about those. Generally speaking as you place more demands
on the engine you are going to increase the wear and increase the risk
of failure.
Sean and I have been disagreeing about what is inside the engine. Even
though the parts may not be any different than your car you can still
place considerable stress on them. You can't draw too many conclusions
from our arguments except that we don't agree!
I do agree with the earlier poster, Bryon. My own asshole, I mean opinion,
is that I like to have enough engine that I can run at an extended
cruising speed I am happy with while at around 2/3 throttle. That's
not to say I won't push the limits. I think that is sensible.
My own boat is currently propped so that I can turn 400 rpm over the
recommended 4,200 wot with a light load and I go there. I'm building a
new 5.7 and it'll be propped for 5,000 rpm. And it'll see that plenty
times. Course I'm using better parts than merc uses.
After all they are just toys. It's not like you need them to get to
work Monday or anything. Course my wife'll be major pissed if I toss
a rod in the middle of skiing season while on the wrong side of wot
rpm! Late night mid week engine swap time!
Lawrence.....
Sean Gilboy
jeff...@execpc.com wrote:
>
> Lawrence wrote:
>
> >In article <56bvkt$7...@bashir.ici.net>, Bryon says...
> >>
> >>4 cycle gas engines are not really made to run at 4500rpm for very long.
>
> How about 6 cylinder engines? Can they run at WOT for very long
> without causing any damage? Mine is not a Merc but is a 4.3 6.
>
> jeff...@execpc.com
> http://www.execpc.com/~jeffishr
> West Allis, WI (Near Milwaukee)
> '91 18' Thundercraft OMC V-6
The engines that OMC or anyone else for that fact can run at 4500 or
what ever wot spec your manufacture has limited the engine to with no
problems.
Sean Gilboy
How could you run your boat at wot all the time because there isn't
enough lake or smooth conditions on an ocean to pull it off. I'm done
with this because if you paid attention to details you would know
better.
Lawrence
In article <3290F4...@mail.vbe.com>, Sean says...
>
<snip>
>
>They are designed to run at 4800 rpm that's why it posted if it couldn't
>do it why would mercruisier recommend it. Also mercrusier has
>enduranced engines at wot for more than 500 hrs so why do you think you
>can't run them wot. There's more to marine engines than meet the eye.
>Why doesn't gm just make them or why doesn't some big time engine
>building shop make them. It more complicated than you a willing to give
>any credit for.
I'll be glad to give them any credit they are due. But it can't be more
than meets the eye. I won't go there. It's a engine. Think about it,
there is barely 20 distinct internal parts in a modern v8. If there are
changes to the engine to increase it's durability then I'd love to learn
the details. I take them apart, I look at blocks at my dealer, I can not
find anything inside the merc 5.7's that is any different from the ones I
examine in cars. The durn blocks aren't even 4 bolt mains.
I wish they had steel cranks, I wish they had pink rods, I wish they had
forged pistons, I wish they had bowtie heads, cause then I'd have some
of that cool stuff. But alas they don't have anything special. Fact is
hipo vettes, camaroes, and gm trucks have more 'heavy duty' parts in
them than a merc 5.7.
As to the durability it's simply tradeoffs. In a car that engine could
easily see 3000 hours. Do you think it would get anywhere near that
in a boat?
GM DOES make them. Merc simply supplies the stickers.
Lawrence......
1329C1000-Garry_Heon(MT4084)NOBIN
In article <329252...@mail.vbe.com>,
Sean Gilboy <se...@mail.vbe.com> wrote:
>1329C1000-Garry_Heon(MT4084)NOBIN wrote:
SNIP for bandwidth
>
>How could you run your boat at wot all the time because there isn't
>enough lake or smooth conditions on an ocean to pull it off. I'm done
>with this because if you paid attention to details you would know
>better.
My boat does see 5000 rpm and up 90% of the time. Takes me about 30
minutes to get to the ocean if I obey all the no-wake zones. From there
have enough ocean around to do it (Atlantic) and my boat, 41' Thoroughbred
Velocity, can more than handle 5' at 70 mph comfortably. I prey for at least
3' - 4' on the ocean, otherwise the ride is boring. Maybe you'd like to come
for a ride?
Sean Gilboy
I've riden in 3 to 4 foot chop in a 38 ft Nortech with twin 500
MerCrusiers with bravo I's. It runs 86 mph even in the chop. Good boat
if you can afford it. But you are constantly in and out of the thorttle
so it doesn't really wot all the time but I understand where you are
coming from.
Larry Butler
ga...@holly.ho.att.com (1329C1000-Garry_Heon(MT4084)NOBIN) wrote:
>My boat does see 5000 rpm and up 90% of the time. Takes me about 30
>minutes to get to the ocean if I obey all the no-wake zones. From there
>have enough ocean around to do it (Atlantic) and my boat, 41' Thoroughbred
>Velocity, can more than handle 5' at 70 mph comfortably. I prey for at least
>3' - 4' on the ocean, otherwise the ride is boring. Maybe you'd like to come
>for a ride?
>
>Garry Heon
>First Stepp
>ga...@holly.mt.lucent.com
>My Opinions....Lucent's Network.
>
mo'!! 70mph...aahhh...Call See-Doo-Doo! Ahm gonna needs me MO POWA!!
MO POWA!!
1329C1000-Garry_Heon(MT4084)NOBIN
In article <3293a624...@news.mindspring.com>,
Ya, but read obey no-wake and take it out in the ocean with me!
Jack Patteeuw
In article <56sdi7$e...@lana.zippo.com>, Lawrence writes:
>
>I wish they had steel cranks, I wish they had pink rods, I wish they had
>forged pistons, I wish they had bowtie heads, cause then I'd have some
>of that cool stuff. But alas they don't have anything special. Fact is
>hipo vettes, camaroes, and gm trucks have more 'heavy duty' parts in
>them than a merc 5.7.
Years ago (1960-70's), when Merc used to buy Ford engines, they typically
bought a bare, not machined, "truck" block and heads. If they bought rods
and/or cranks, they were also the "truck" version (typically forged back
then). Pistons were typically bought from supplier (typically the same one
Ford used) and they had a unique crown (probably thicker). Cams were also
bought through suppliers at Merc specs.
Ford and GM don't really make "truck" blocks, cranks or rods any more. GM
does make and sells lots of "good" parts to the after market and includes
some of them on their high performance cars (such as 'vetes and camaros).
The circle is coming around again. Even though the new Ford "modular" V8
are a very thin wall casting, they do have deep skirted blocks and cross
bolted main and the cast pan acts as a girdle. I also think we have a
forged crank and pistons on the 4.6L-4V engine. Unfortunately, those
powdered metal rods give me the "willies" !
Jack Patteeuw
My opinions are my own and not my employer's, my wife's, or my children !
"I used to do VMS, Stolen from a good friend:
Now I do Unix; "A mind is like a parachute ...
It's a living" It only works when it is open !"
Jack Patteeuw
In article <56spdl$4...@nntpa.cb.lucent.com>,
ga...@holly.ho.att.com (1329C1000-Garry_Heon(MT4084)NOBIN) writes:
<SNIP>
>I'd like to see any marine gas engine run at rated WOT under load for 500
>hours. I've been in the high performance end of things for a long time and
>have yet to see an engine that's been run hard last 500 hours without a
>rebuild.
There is a **HUGE** difference between a "stock" marine engine and a high
performance one ! Stock marine engine are typically limited in the amount
of hp they make (via cam/carb) so that they **CAN** run at rated WOT rpm
for extended times. High performance engines, of course, are designed to
give the maximum amount of horsepower, just long enough to win the race and
then they explode ;-) !! With proper maintenance and a design that
provides adequate cooling and oiling, the correct spark advance and fuel
with adequate octane, I see no reason why a marine-ized automotive engine
could **NOT** run 500 hrs, under load, at max rated rpm.
>In fact they were
>building some of the Corvette engines for GM. I believe it was the engine GM
>co-developed with Lotus.
True. this was an all aluminum 350 cid V8. I think it was a 2 valve
pushrod, but I could be wrong. GM doesn't use it anymore (too expensive).
>I really
>think you should say that marine engines are _different_ than automotive.
>An automotive application isn't the best choice for a boat because the
>power curve is different. Most automotive mechanics don't know the
>correct cam grind for marine engines, not because they more complicated,
>just because they're not familiar with the application.
I agree. One other thing is that automotive engines are not designed to
run under high loads, at max rpm, for really long (> 500 hrs) periods.
That is why you typically won't find automotive gasoline engines in
commercial boats.
bo...@dircon.co.uk
Try this one with your standard car engine
Start it once a week or so, carry around a 10,000 gallon cooling
resevoir so it never reaches it's designed working temperature, fit a
bloody silly auto choke that washes lubricant from the cylander walls
for up to five minutes even in temperate climates and dilutes whats
left in the sump, run it under loads it was never designed to be run
at, put it in an enclosed space and create a nice damp atmosphere, Oh
and remember not to service it properly. It's no wonder the poor
little buggers cause problems.
Regards Bonny
Keith Beckmann
bo...@dircon.co.uk wrote:
: Try this one with your standard car engine
: Regards Bonny
1st, I start it at least twice a week during the summer. It has a
thermostat and reaches 160 degrees in a few minutes. The choke only
creates a rich environment for starting, and is 1/2 open as soon as there
is vacuum.
I can't answer the part about what load the engine was designed for, but I
must assume that some engineer someplace said that it would work in this
size boat, at this RPM.
It seems like I do more idling than cruising, since it's 30 minutes at
no-wake to open water. Most days on the lake are to rough for WOT, so the
engine only runs at 3000-3500 RPM. The two times this summer that it was
extra nice out, and was able to open it up to WOT for 15 minutes it quit.
Is 15 minutes an excessive amount of time to run at WOT?? I think not!!!
As for Maintenance, I put 88 motor hours on this season. The engine has
had it's oil changed 3 times, and the outdrive oil changed twice. I've
had the plugs replaced mid-season, and timing checked. Of course there
has been the normal other checks to see that everything else is OK.
---------
Internet: kbec...@earth.execpc.com
kbec...@solaria.sol.net
keith.b...@bbs.execpc.com