Spark plugs seized in aluminum head...
vy...@ico.com
Baker) wrote:
> I would like to know how common plug seizing in aluminum heads is, and
> what people's recommendations for avoiding it are.
>
I own a Honda Integra (145,000 miles) with an aluminum head and change the
plugs every 30,000 miles. When I change them, I make sure the gap is set
correctly, spray the threads with WD-40, and torque them to 20-25 ft. lbs.
with an accurate torque wrench. Using this method, my plugs are never a
problem to remove.
WILLIAM EDELBROCK
writes:
>
>One of the spark plugs on my car recently seized in the aluminum head,
and
>some of the others were very difficult to get out.
>
>I asked the people at Champion Spark Plug how common this problem was,
and
>they indicated that it was most common among mechanics who either
overtorqued
>the plugs, or used the wrong kind of antiseize compound on the threads
(i.e.,
>compound not suitable for high temperature use).
>
>Champion recommended that when replacing spark plugs in an aluminum
head,
>one should 1) make sure the engine is cold; 2) make sure the threads
are
>completely clean, so that the plugs screw in easily; 3) that you _not_
>use any antiseize compound (according to them, the plating itself is
>antiseize); and 4) that you not overtorque the plugs.
>
>----
>
>I would like to know how common plug seizing in aluminum heads is, and
>what people's recommendations for avoiding it are.
>
The most common cause for plugs to sieze in aluminum heads is
removing them when the engine is warm. Aluminum and steel expand at
different rates and temperatures. If you attempt to remove the plugs
with the engine warm, the threads may actually cut into the aluminum
causing them to sieze. Anti-sieze compound is not recommended and the
plugs should be torqued to specification upon installation. (yes this
requires a torque wrench).
Bill Edelbrock
Ron's Automotive Clinic Inc.
Long Beach, CA
Automotive Technical Instructor
Automotive Diagnostics
SPx Corporation
Henry Baker
some of the others were very difficult to get out.
I asked the people at Champion Spark Plug how common this problem was, and
they indicated that it was most common among mechanics who either overtorqued
the plugs, or used the wrong kind of antiseize compound on the threads (i.e.,
compound not suitable for high temperature use).
Champion recommended that when replacing spark plugs in an aluminum head,
one should 1) make sure the engine is cold; 2) make sure the threads are
completely clean, so that the plugs screw in easily; 3) that you _not_
use any antiseize compound (according to them, the plating itself is
antiseize); and 4) that you not overtorque the plugs.
----
I would like to know how common plug seizing in aluminum heads is, and
what people's recommendations for avoiding it are.
Thanks in advance.
--
www/ftp directory:
ftp://ftp.netcom.com/pub/hb/hbaker/home.html
George B
>I would like to know how common plug seizing in aluminum heads is, and
>what people's recommendations for avoiding it are.
>
>Thanks in advance.
>
>--
>www/ftp directory:
>ftp://ftp.netcom.com/pub/hb/hbaker/home.html
I see it mostly in the 4 cyl. models. I suspect that some folks either
install plugs in a warm engine (a no-no on aluminum heads) or overtighten
the plugs. The threads on the plugs are a lot stronger than the aluminum of
the head and it is easy to gall/strip the threads. It can be nearly
impossible to get those plugs out!
George Bonser
gr...@cris.com
Carlton Fung
trucks? Is it worth doing for better stopping distances?
Mark Gums
> One of the spark plugs on my car recently seized in the aluminum head, and
> some of the others were very difficult to get out.
I have a Geo Tracker with 8K on it and found them hard to get out. These were the
factory plugs(N-Denso) and I was real surprised. Put in Champions, with the proper
anti-sieze.
> I would like to know how common plug seizing in aluminum heads is, and
> what people's recommendations for avoiding it are.
Well, I recommend, going over the threads with a chaser(be VERY careful, do this
by hand -no ratchet- only!) when changing, and use an anti-sieze made specifically
for the plugs. You'll never have problems. Later. -Mark
John S.
> In <hbaker-0209...@192.0.2.1> hba...@netcom.com (Henry Baker)
> writes:
> >
> >One of the spark plugs on my car recently seized in the aluminum head,
> and
> >some of the others were very difficult to get out.
> >
> and
> >they indicated that it was most common among mechanics who either
> overtorqued
> >the plugs, or used the wrong kind of antiseize compound on the threads
> (i.e.,
> >compound not suitable for high temperature use).
> >
> >Champion recommended that when replacing spark plugs in an aluminum
> head,
> >one should 1) make sure the engine is cold; 2) make sure the threads
> are
> >completely clean, so that the plugs screw in easily; 3) that you _not_
> >use any antiseize compound (according to them, the plating itself is
> >antiseize); and 4) that you not overtorque the plugs.
> >
> >----
> >
> >what people's recommendations for avoiding it are.
> >
>
> The most common cause for plugs to sieze in aluminum heads is
> removing them when the engine is warm. Aluminum and steel expand at
> different rates and temperatures. If you attempt to remove the plugs
> with the engine warm, the threads may actually cut into the aluminum
> causing them to sieze. Anti-sieze compound is not recommended and the
> plugs should be torqued to specification upon installation. (yes this
> requires a torque wrench).
>
>
> Bill Edelbrock
> Ron's Automotive Clinic Inc.
> Long Beach, CA
>
> Automotive Technical Instructor
> Automotive Diagnostics
> SPx Corporation
>
Okay, now I'm confused. I'm damn near 99.9999% certain that the sticker
on the fender of my 1988 Chevy Celebrity warns that the spark plugs
should be removed when the engine is *warm*. I haven't had to change
them yet, but I'd appreciate a definite answer. In the meantime I'll
double check that sticker.
Dana B. Craig
Baker) wrote:
> One of the spark plugs on my car recently seized in the aluminum head, and
> some of the others were very difficult to get out.
>
> I asked the people at Champion Spark Plug how common this problem was, and
> they indicated that it was most common among mechanics who either overtorqued
> the plugs, or used the wrong kind of antiseize compound on the threads (i.e.,
> compound not suitable for high temperature use).
>
> Champion recommended that when replacing spark plugs in an aluminum head,
> one should 1) make sure the engine is cold; 2) make sure the threads are
> completely clean, so that the plugs screw in easily; 3) that you _not_
> use any antiseize compound (according to them, the plating itself is
> antiseize); and 4) that you not overtorque the plugs.
>
> ----
>
> I would like to know how common plug seizing in aluminum heads is, and
> what people's recommendations for avoiding it are.
>
> Thanks in advance.
________________
I've been racing with aluminum heads now for many years. During the race
night, we R and R our plugs many many times. In all of this, I have only
had a proplum one time one time. It was during a red flag we decided to
change the plugs, the car had a misfire that we found out to be a bad
plug. When changing the plugs, a new member to the team installed the
plug to tight. Later that night wh we had to have our engine pumped, (we
won the race) we could not get the plugs out! When we did, the threds
came out with the plug. We had to fix the threds to allow the tech
inspecter the oppertunity to pump the engine or forfeit the race.
We don't use any type of compound, there is more risk of contamination to
the motor when you do. Thats what fouled out the plug earler in the race,
and since that time, we just us clean plugs lightly torgued in a warm
motor. It works for us.
--
Dana B. Craig
Max Crittenden
> In article <42bhg7$7...@ixnews7.ix.netcom.com>, thun...@ix.netcom.com
(WILLIAM EDELBROCK ) writes:
> > The most common cause for plugs to sieze in aluminum heads is
> > removing them when the engine is warm. Aluminum and steel expand at
> > different rates
> Okay, now I'm confused. I'm damn near 99.9999% certain that the sticker
> on the fender of my 1988 Chevy Celebrity warns that the spark plugs
> should be removed when the engine is *warm*.
I think Mr. Edelbrock is wrong and your sticker is right. Yes, aluminum
and steel have different expansion rates: aluminum expands more with
temperature. But this does not mean that the aluminum head swells up and
grabs the plug; what it means is that the spark plug hole gets _bigger_
relative to the plug. So it should definitely be easier to get the plug
out with the engine is warm. I wish I'd thought about this a couple of
months ago before I stripped a plug thread.
Max Crittenden
Henry Baker
max_cri...@qm.sri.com (Max Crittenden) wrote:
> > > The most common cause for plugs to sieze in aluminum heads is
> > > removing them when the engine is warm. Aluminum and steel expand at
> > > different rates
>
> Yes, aluminum
> and steel have different expansion rates: aluminum expands more with
> temperature. But this does not mean that the aluminum head swells up and
> grabs the plug; what it means is that the spark plug hole gets _bigger_
> relative to the plug. So it should definitely be easier to get the plug
> out with the engine is warm. I wish I'd thought about this a couple of
> months ago before I stripped a plug thread.
OK, so perhaps the recommendation should go like this??
Take the plugs _out_ when the engine is _warm_, but
put the plugs _in_ when the engine is _cold_??
Or perhaps, if you install plugs in a hot engine, make sure the plugs
are also hot??
Does anyone know the definitive answer to this??
Perhaps the Defense Department knows about this -- they've been using
aluminum heads & plugs as long as anyone, and they've probably done research
on every possible combination of warm engine, cold plug, etc.
Does anyone know anything about plugs in tanks or airplanes??
Colin Urquhart
: In article <hbaker-0209...@192.0.2.1>, hba...@netcom.com says...
: >I would like to know how common plug seizing in aluminum heads is, and
: >what people's recommendations for avoiding it are.
: >
: >Thanks in advance.
: >
: >--
: >www/ftp directory:
: >ftp://ftp.netcom.com/pub/hb/hbaker/home.html
: I see it mostly in the 4 cyl. models. I suspect that some folks either
: install plugs in a warm engine (a no-no on aluminum heads) or overtighten
: the plugs. The threads on the plugs are a lot stronger than the aluminum of
: the head and it is easy to gall/strip the threads. It can be nearly
: impossible to get those plugs out!
: George Bonser
: gr...@cris.com
--
=======================
Colin Urquhart
Hewlett-Packard Ltd. I'm going downhill fast....
Scotland (Speed ski-ing of course!!)
col...@hpsqf.sqf.hp.com
=======================
Dick Brewster
>In article <42hths$6...@post.gsfc.nasa.gov>, w...@glacier.stx.com wrote:
>
>> In article <42bhg7$7...@ixnews7.ix.netcom.com>, thun...@ix.netcom.com
>(WILLIAM EDELBROCK ) writes:
>
>> > removing them when the engine is warm. Aluminum and steel expand at
>> > different rates
Aluminum expands at about three times the rate of steel. Plugs are easier to
remove from aluminum heads when the heads are hot. I've removed several "siezed"
plugs by getting the engine warm then trying again. Don't get overly torquey
when removing plugs from a warm head though, some aluminum alloys start to get
weaker and gall easier at fairly low temperatures.
Whatever you do, don't put plugs into a warm aluminum head unless you want to
risk having them sieze. If you torque them down in a warm head, when the head
cools you have a nice shrink fit. This doesn't always result in a siezed plug,
but it increases the risk.
>
>> Okay, now I'm confused. I'm damn near 99.9999% certain that the sticker
>> on the fender of my 1988 Chevy Celebrity warns that the spark plugs
>> should be removed when the engine is *warm*.
>
>I think Mr. Edelbrock is wrong and your sticker is right. Yes, aluminum
>and steel have different expansion rates: aluminum expands more with
>temperature. But this does not mean that the aluminum head swells up and
>grabs the plug; what it means is that the spark plug hole gets _bigger_
>relative to the plug.
Yup.
So it should definitely be easier to get the plug
>out with the engine is warm. I wish I'd thought about this a couple of
>months ago before I stripped a plug thread.
>
>Max Crittenden
WILLIAM EDELBROCK
>>> Okay, now I'm confused. I'm damn near 99.9999% certain that the
>sticker
>>> on the fender of my 1988 Chevy Celebrity warns that the spark plugs
>>> should be removed when the engine is *warm*.
>>
>>I think Mr. Edelbrock is wrong and your sticker is right. Yes,
>aluminum
>>and steel have different expansion rates: aluminum expands more with
>>temperature. But this does not mean that the aluminum head swells up
>and
>>grabs the plug; what it means is that the spark plug hole gets
>_bigger_
>>relative to the plug. So it should definitely be easier to get the
>plug
>>out with the engine is warm. I wish I'd thought about this a couple
>of
>>months ago before I stripped a plug thread.
>>
>>Max Crittenden
>
> You are correct in stating that when the aluminum is hot the spark
>plug hole enlarges. What you neglected to mention was that aluminum
>also dissipates heat at a greater rate than steel and the spark plug
>hole would resume it's "cold size" before the threads of the spark
plug
>would resume their "cold size". Therefore, the spark plug could be a
>larger size under these conditions. The information released by
>AC/Delco to those of us in the biz recommends the removal of the plugs
>on a cold engine (cold is a 2 hour rest).
>
>Bill Edelbrock
>Ron's Automotive Clinic Inc.
>Long Beach, CA
>
>Automotive Technical Instructor
>Automotive Diagnostics
>SPx Corporation
>
Looked at an 89 Corsica today, the emission label had this warning;
"NOTE - DAMAGE TO HEADS MAY RESULT IF ENGINE IS NOT ALLOWED TO COOL
BEFORE REMOVING SPARK PLUG". Go figure.
mbu...@access.k12.wv.us
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In article <hbaker-0509...@192.0.2.1>, <hba...@netcom.com> writes:
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> Newsgroups: rec.autos.sport.tech,rec.autos.tech
> Subject: Re: Spark plugs seized in aluminum head...
> Message-ID: <hbaker-0509...@192.0.2.1>
> From: hba...@netcom.com (Henry Baker)
> Date: Tue, 5 Sep 1995 22:21:14 GMT
> Sender: hba...@netcom14.netcom.com
> References: <hbaker-0209...@192.0.2.1>
<42bhg7$7...@ixnews7.ix.netcom.com>
> <42hths$6...@post.gsfc.nasa.gov>
<max_crittenden-...@128.18.42.2>
> Organization: nil organization
> Lines: 34
> Xref: wvnvms rec.autos.sport.tech:2768 rec.autos.tech:94085
>
> In article <max_crittenden-...@128.18.42.2>,
> max_cri...@qm.sri.com (Max Crittenden) wrote:
>
> > > > The most common cause for plugs to sieze in aluminum heads is
> > > > removing them when the engine is warm. Aluminum and steel expand at
> > > > different rates
> >
> > Yes, aluminum
> > and steel have different expansion rates: aluminum expands more with
> > temperature. But this does not mean that the aluminum head swells up and
> > grabs the plug; what it means is that the spark plug hole gets _bigger_
> > relative to the plug. So it should definitely be easier to get the plug
> > out with the engine is warm. I wish I'd thought about this a couple of
> > months ago before I stripped a plug thread.
>
> OK, so perhaps the recommendation should go like this??
>
> Take the plugs _out_ when the engine is _warm_, but
> put the plugs _in_ when the engine is _cold_??
>
> Or perhaps, if you install plugs in a hot engine, make sure the plugs
> are also hot??
>
> Does anyone know the definitive answer to this??
>
> Perhaps the Defense Department knows about this -- they've been using
> aluminum heads & plugs as long as anyone, and they've probably done research
> on every possible combination of warm engine, cold plug, etc.
>
> Does anyone know anything about plugs in tanks or airplanes??
>
> --
> www/ftp directory:
> ftp://ftp.netcom.com/pub/hb/hbaker/home.html
Try using antisieze on the plug threads when installing them. If they are
already stuck, try taking them out when the engine is warm. If they still
strip, you may have to install a helicoil(thread repair).
Dennis L Goodrich
anti-sieze compound. Should I remove them, now, and wipe of the
compound or just let it go?
Denny Goodrich
dlgo...@iastate.edu
--
Dennis L Goodrich
dlgo...@iastate.edu
Chris Chubb
>
>Anyone have experiance with rear disc brake coversions on pick-up
>trucks? Is it worth doing for better stopping distances?
Mabye if you were hauling at least a half tonne. If you used rear disks
on an unladden PU, without ABS or a gravity adjusted proportioning valve,
you would just lock up the rears every time you hit the brakes.
Chances are that you already have the capability to lock up the rears
anyway, with a gravity adjusted proportioning valve in there
already.
--
Chris Chubb -- cch...@ida.org (Alexandria, VA)
** Leading a life of noisy desperation. **
My opinions and $0.75 will get you a cup of coffee.
Jonathan R Barnes
>>> > The most common cause for plugs to sieze in aluminum heads is
>>> > removing them when the engine is warm. Aluminum and steel expand
>at different rates
>what it means is that the spark plug hole gets_bigger_
>relative to the plug. So it should definitely be easier to get the
>plug
But the hole also gets longer, efectifly changing the thread
pitch and maybe locking the plug, so it's not a shure bet that
heat will help.
Jonathan.
John L. Scarfone
The factory service manual for my car (Honda Civic) advises to use a
_small_ amount of anti-seize compound on the threads. You might want
to check with the manufacturer.
~sig withheld by request
Dick Brewster
>In <42n93f$a...@news.iastate.edu> dlgo...@iastate.edu (Dennis L
>Goodrich) writes:
>>
>>Hmmmm. I recently put new plugs in my engine and dutifully used an
>>anti-sieze compound. Should I remove them, now, and wipe of the
>>compound or just let it go?
>>
>>Denny Goodrich
>>dlgo...@iastate.edu
>>--
>>Dennis L Goodrich
>>dlgo...@iastate.edu
>
I have dutifully used anti-sieze on spark plugs in aluminum heads since about
1959 (Ford Flathead with Offenhauser heads, sorry Bill, but it did have an
Edelbrock intake manifold (:-) I have never had a plug that was anti-siezed
stick, nor have I ever had any other anti-sieze related problems.
I started off with a can of US gumm'nt anti sieze that an Air Force engine
mechanic gave me. I presently use Permatex high temperature, high performance
anti sieze. Whatever anti-sieze you use, don't get any on the electrodes.
And whatever you do, don't use an anti-sieze with graphite in it. That's a
nasty corrosion combination with aluminum and steel.
> I think the reason that anti-sieze is not recommended is because
>the anti-sieze compound may contain materials that impede the plugs
>ability to disipate heat. I know some anti-sieze compounds contain
>(silica?) glass beads which would reduce heat transfer between the plug
>shell and the head. This may be why anti-sieze is not recommended.
There may be some truth to this, although I could never tell the differance when
reading spark plugs. I've heard that anti-sieze can make a plug act 1/4 to 1/2
heat range hotter.
>
>Bill Edelbrock
>Ron's Automotive Clinic Inc.
>Long Beach, CA
Any relation?
Cheers
Dick Brewster
>>>
>>>Max Crittenden
>>
>> You are correct in stating that when the aluminum is hot the spark
>>plug hole enlarges. What you neglected to mention was that aluminum
>>also dissipates heat at a greater rate than steel and the spark plug
>>hole would resume it's "cold size" before the threads of the spark
>plug
>>would resume their "cold size". Therefore, the spark plug could be a
>>larger size under these conditions. The information released by
>>AC/Delco to those of us in the biz recommends the removal of the plugs
>>on a cold engine (cold is a 2 hour rest).
>>
>>Bill Edelbrock
>>Ron's Automotive Clinic Inc.
>>Long Beach, CA
>>
>>Automotive Technical Instructor
>>Automotive Diagnostics
>>SPx Corporation
>>
>
> Looked at an 89 Corsica today, the emission label had this warning;
>"NOTE - DAMAGE TO HEADS MAY RESULT IF ENGINE IS NOT ALLOWED TO COOL
>BEFORE REMOVING SPARK PLUG". Go figure.
>
That may because some aluminum gets weaker at relatively low temperature. They
may also be concerned that someone will put the new plugs in before the head
cools. When I have run across stuck spark plugs in other peoples cars, Warming
up the engine has solved the problem every time I have tried it.
I agree you should try to remove the plugs cold, then if you are afraid that you
will strip the head before the plug comes out, try it with the engine warm.
Then if the head strips, fix it (:-)
Cheers
Julia Brannon Cook
: !In article <hbaker-0209...@192.0.2.1>, hba...@netcom.com (Henry
: Baker) wrote:
: ________________
: I've been racing with aluminum heads now for many years. During the race
: night, we R and R our plugs many many times. In all of this, I have only
: had a proplum one time one time. It was during a red flag we decided to
: change the plugs, the car had a misfire that we found out to be a bad
: plug. When changing the plugs, a new member to the team installed the
: plug to tight.
I am the only crew my husband and three of our friends have at SCCA
national races. Changing plugs in a hot engine during practice or
qualifying is about the only thing I have to do that *really* makes me
nervous. I loosen them (only) with a ratchet wrench then remove them by
hand and replace them until they seat by hand and carefully tighten with
a ratchet wrench but do not torque them in the pits. Even though I've
done this succesfully numerous times I am always afraid of
cross-threading a plug. Does anyone have any suggestions for those of
us who find we *have* to change plugs in hot aluminum heads to make this
a safer procedure?
Julie Cook
Javier Resto
max_cri...@qm.sri.com says...
some stuff deleted..
>I think Mr. Edelbrock is wrong and your sticker is right. Yes, aluminum
>and steel have different expansion rates: aluminum expands more with
>temperature. But this does not mean that the aluminum head swells up and
>grabs the plug; what it means is that the spark plug hole gets _bigger_
>relative to the plug. So it should definitely be easier to get the plug
>out with the engine is warm. I wish I'd thought about this a couple of
>months ago before I stripped a plug thread.
>
>Max Crittenden
--
When aluminum or any other metal is heated up it will expand or try expand in
all directions. If the part being heated has a hole on it the hole is going
to get bigger because the atoms around the perimeter of the hole are going to
push out on each other making the circunference of the hole longer. Also, the
length of the threaded hole is going to get longer, and since it is not going
to "grow" any more threads than the ones it already has, the pitch is going to
change. This means that if your are trying to install a spark plug that is at
room temperature into an aluminum head that is, lets say, 100 degrees higher
your are going to have a difference in threaded lenght (assuming the the
threaded section is about 3/8" long) of around half of one thousand of an
inch. This does not seem to be much but a will bet you that the stresses
developed in the aluminum part are going to be enough to destroy the threads.
In addition, if you try to remove the spark plug after the engine is at room
temperature an increase in radial interference as the aluminum cools down. In
conclusion, the threads were deformed when the spark plug was installed the
first time and then destroyed when it was removed the second time.
*****************************************************************
Javier Resto "If the NECESSITY is the *
Propulsion Systems Branch mother of invention, *
NASA Lewis Research Center LAZINESS must be its father."*
Cleveland, OH 44135 Anonymous *
rey...@porky.lerc.nasa.gov *
*****************************************************************
John S.
WILLIAM EDELBROCK wrote:
> The most common cause for plugs to sieze in aluminum heads is
> removing them when the engine is warm. Aluminum and steel expand at
> with the engine warm, the threads may actually cut into the aluminum
> causing them to sieze. Anti-sieze compound is not recommended and the
> plugs should be torqued to specification upon installation. (yes this
> requires a torque wrench).
to which I responded with:
> Okay, now I'm confused. I'm damn near 99.9999% certain that the sticker
> on the fender of my 1988 Chevy Celebrity warns that the spark plugs
> should be removed when the engine is *warm*.
and after a bit of debate, WILLIAM EDELBROCK wrote:
> > You are correct in stating that when the aluminum is hot the spark
> >plug hole enlarges. What you neglected to mention was that aluminum
> >also dissipates heat at a greater rate than steel and the spark plug
> >hole would resume it's "cold size" before the threads of the spark
> plug
> >would resume their "cold size". Therefore, the spark plug could be a
> >larger size under these conditions. The information released by
> >AC/Delco to those of us in the biz recommends the removal of the plugs
> >on a cold engine (cold is a 2 hour rest).
[snip]
>
> Looked at an 89 Corsica today, the emission label had this warning;
> "NOTE - DAMAGE TO HEADS MAY RESULT IF ENGINE IS NOT ALLOWED TO COOL
> BEFORE REMOVING SPARK PLUG". Go figure.
>
> Bill Edelbrock
> Ron's Automotive Clinic Inc.
> Long Beach, CA
>
Well I did say I was only 99.9999% certain. And when I did a double
check, I found the exact same warning that Bill found on the Corsica. Go
figure. The idea of different cooling rates was something I had missed.
Makes sense to me. Of course, I have no intentions of trying to change
the plugs on this car myself anyhow. At least not those three plugs
jammed up against the firewall. I'll gladly pay someone to do that for
me. That way if the threads get boogered, they get to fix it. (Damned
sideways engine. Who the hell came up with that idea, anyway?!?!)
Dick Brewster
Delitia ----------
>
>--
>When aluminum or any other metal is heated up it will expand or try expand in
>all directions. If the part being heated has a hole on it the hole is going
>to get bigger because the atoms around the perimeter of the hole are going to
>push out on each other making the circunference of the hole longer. Also, the
>length of the threaded hole is going to get longer, and since it is not going
>to "grow" any more threads than the ones it already has, the pitch is going to
>change. This means that if your are trying to install a spark plug that is at
>room temperature into an aluminum head that is, lets say, 100 degrees higher
>your are going to have a difference in threaded lenght (assuming the the
>threaded section is about 3/8" long) of around half of one thousand of an
>inch. This does not seem to be much but a will bet you that the stresses
>developed in the aluminum part are going to be enough to destroy the threads.
How big a bet are you willing to make (:-)
Threaded fasteners the size of spark plugs are made to for looser tolerances than the
0.0005 inch that you suggest would cause a spark plug to fail. Even if they weren't,
you could easily displace a single thread in a low grade head casting 0.003 without
causing it to fail.
>
>In addition, if you try to remove the spark plug after the engine is at room
>temperature an increase in radial interference as the aluminum cools down. In
>conclusion, the threads were deformed when the spark plug was installed the
>first time and then destroyed when it was removed the second time.
>
This has been demonstrated, except that the distortion that occurs when installing
the plug is not significant when compared to normal thread tolerances.
Cheers
Henry Baker
(Julia Brannon Cook) wrote:
> Does anyone have any suggestions for those of
> us who find we *have* to change plugs in hot aluminum heads to make this
> a safer procedure?
So far, the only thing that occurs to me would be to compute the temperature
that would make the spark plugs expand as much as the head at operating
temperature, and keep the spark plugs that hot. Since someone else
suggested that aluminum expands 3X as fast as steel, this would seem to
imply that the spark plugs would have to be quite a bit hotter than
the aluminum heads, which would run the risk of turning the aluminum
very soft.
Perhaps someone could calculate what torque _should_ be applied when the
heads are warm and the plugs are cold. It probably isn't nearly as high
as when both are cold, but I haven't done the calculation.
Dick Brewster
>: !In article <hbaker-0209...@192.0.2.1>, hba...@netcom.com (Henry
>: Baker) wrote:
>
>: ________________
>: I've been racing with aluminum heads now for many years. During the race
>: night, we R and R our plugs many many times. In all of this, I have only
>: had a proplum one time one time. It was during a red flag we decided to
>: change the plugs, the car had a misfire that we found out to be a bad
>: plug. When changing the plugs, a new member to the team installed the
>: plug to tight.
>
>I am the only crew my husband and three of our friends have at SCCA
>national races. Changing plugs in a hot engine during practice or
>qualifying is about the only thing I have to do that *really* makes me
>nervous. I loosen them (only) with a ratchet wrench then remove them by
>hand and replace them until they seat by hand and carefully tighten with
>a ratchet wrench but do not torque them in the pits. Even though I've
>done this succesfully numerous times I am always afraid of
>a safer procedure?
>
>
Julie, Since you have actually delt with putting spark plugs in hot heads
and you didn't mention any problems removing the plugs later, YOU are an
expert in the field. How tight do you tighten the plugs when you installed
them? Have you ever had any problems removing them later?
As far as installing them goes, you should use the lightest socket you can
find or make, with a rubber liner to center and hold the plug. Make a
handle that is also as light as practical and is long enough and
comfortable to use. You might try turning dowm a good spark plug socket on
a lathe until it is just thick enough to stand up to your finger tight plug
twisting and make a handle that is esy to use out of wood and epoxy it into
the socket. The idea here is to keep the weight down so you can feel how
the plug is going in and to control the plug (rubber lined socket) so it
will be pointed the same way the socket is pointed.
Of course you will have to use another socket to tighten the plug.
ROBERT WAGNER
Maine Forest SCCA pro rally, and came in first in class, eleventh overall. This 96
had the same rear disc conversion that is going into my own SAAB 96 as I write this.
It's not a cure-all for stopping distances, but with a proportioning valve and a
hydraulic handbrake acting on the rears, it allows far greater control and
eliminates much of the doglike understeer of front drive cars. Can't speak for
pickups, but wanted to give you this one vote PRO rear disc conversions...
Cheers,
Rob
Javier Resto
>
>javier...@lerc.nasa.gov (Javier Resto) wrote:
>
>Delitia ----------
>
>
>>
>>--
>>When aluminum or any other metal is heated up it will expand or try expand
in
Stuff deleted
>>
>>In addition, if you try to remove the spark plug after the engine is at room
>>temperature an increase in radial interference as the aluminum cools down.
In
>>conclusion, the threads were deformed when the spark plug was installed the
>>first time and then destroyed when it was removed the second time.
>>
>
>
>This has been demonstrated, except that the distortion that occurs when
installing
>the plug is not significant when compared to normal thread tolerances.
>
>Cheers
Dick,
Tolerances do not have anything to do with this problem. In threaded
connections the threads on both parts are supposed to make contact. Can you
imagine what will hapen if they do not make contact? Any thermal grow
differential will cause interference. How much damage is done to the threads
depends on how much the difference between the pitch of both the hole and the
fastener is. Remember, you do not need a difference in pitch of a half of a
mile to created large stresses, a few tenths of a thou will do it depending on
the strength of the material being used.
You should not bet your money that easily.;-)
Best Wishes,
--
FattoGatto
depending on thread size. Stripped holes can be repaired in the field
with the head in place, taking about 30 minutes. Uses a steel insert with
special thread and seat cutters. If in need, contact me through private
E-Mail or on CServe, 71143,25
brand...@condor.navsses.navy.mil
Am I missing something here? If I put a bit of anti-sieze on the plug threads
on my VW's YUGO's, or FIATS, I NEVER had a problem with plugs siezing hot OR
cold! Seems like a real simple solution to me... or have I just been incredibly
lucky?
Gordon Pritchard
>Am I missing something here? If I put a bit of anti-sieze on the plug threads
>on my VW's YUGO's, or FIATS, I NEVER had a problem with plugs siezing hot OR
>cold! Seems like a real simple solution to me... or have I just been incredibly
>lucky?
I do this too, with my Subaru. Someone _did_ once mention the
possibililty of oxygen sensor fouling from the antiseize compound, but
no such problems yet. YMMV.
Gordon Pritchard, VE7AGW
***********************************************************************
* My opinions only. *
* E-mail: gpri...@vanieee.wimsey.bc.ca *
* 1954 Chev 1/2 ton (perpetual project) *
* -small-block, posi, frame stretch...*
***********************************************************************
Les Bartel
> Compression tests have been replaced by either a cylinder leak down
> test or an amperage draw test. The amperage draw test is my preference.
> It is non-invasive, but it requires an engine analyzer. The analyzer
> kills the ignition while the engine is cranking and measures the
> amperage draw required to push each piston on the compression stroke.
> It then enables the ignition to identify #1 or the sync cylinder and
> provides the results. A cylinder with low compression requires less
> amperage to push the piston and is therefore easily identified. It is
> also less costly (in most cases) to the consumer to have this performed
> instead of a compression test.
Sounds neat! Of course the equipment cost is significantly greater than
with the old method.
And you still can't do a wet (oil) test vs a dry (no oil) test to determine
where the leak occurs (valves/rings). Unless they have sensors in various
locations (crankcase, carb/intake, exhaust) to determine where air is
leaking.
- les
--
Les Bartel
Intergraph Corporation
Electronics Division
Huntsville, AL
ljba...@ingr.com
(205) 730-8537
william edelbrock
writes:
>
>
>In article <42ng9k$3...@ixnews7.ix.netcom.com>, thun...@ix.netcom.com
(WILLIAM EDELBROCK ) writes:
>
>>
>> Looked at an 89 Corsica today, the emission label had this
warning;
>> "NOTE - DAMAGE TO HEADS MAY RESULT IF ENGINE IS NOT ALLOWED TO COOL
>> BEFORE REMOVING SPARK PLUG". Go figure.
>>
>
>be warm for it.
Compression tests have been replaced by either a cylinder leak down
test or an amperage draw test. The amperage draw test is my preference.
It is non-invasive, but it requires an engine analyzer. The analyzer
kills the ignition while the engine is cranking and measures the
amperage draw required to push each piston on the compression stroke.
It then enables the ignition to identify #1 or the sync cylinder and
provides the results. A cylinder with low compression requires less
amperage to push the piston and is therefore easily identified. It is
also less costly (in most cases) to the consumer to have this performed
instead of a compression test.
Gavin Walker
>
> Looked at an 89 Corsica today, the emission label had this warning;
> "NOTE - DAMAGE TO HEADS MAY RESULT IF ENGINE IS NOT ALLOWED TO COOL
> BEFORE REMOVING SPARK PLUG". Go figure.
>
Then how are you supposed to do a compression test? The engine has to
be warm for it.
--
_--_|\ -|- Gavin Walker
/ \ |
\_.--.*/ <- Canberra, ga...@cbr.dit.csiro.au
v Australia Phone +61-6-2167030 Fax +61-6-2167111
william edelbrock
Bartel) writes:
>
>In article <43b65a$b...@ixnews3.ix.netcom.com>, thun...@ix.netcom.com
(william edelbrock ) writes:
down
>> test or an amperage draw test. The amperage draw test is my
preference.
>> It is non-invasive, but it requires an engine analyzer. The analyzer
>> kills the ignition while the engine is cranking and measures the
>> amperage draw required to push each piston on the compression
stroke.
>> It then enables the ignition to identify #1 or the sync cylinder and
>> provides the results. A cylinder with low compression requires less
>> amperage to push the piston and is therefore easily identified. It
is
>> also less costly (in most cases) to the consumer to have this
performed
>> instead of a compression test.
>
than
>with the old method.
>
>And you still can't do a wet (oil) test vs a dry (no oil) test to
determine
>where the leak occurs (valves/rings). Unless they have sensors in
various
>locations (crankcase, carb/intake, exhaust) to determine where air is
>leaking.
>
> - les
>
That is what the cylinder leak down test is for. The cylinder is
pressurized with the valves closed and you look to see where the air is
escaping, if it comes out the crankcase it is rings/piston if it comes
out exhaust pipe it is ex. valve if it comes out the induction it is
in. valve and if it comes out the radiator it is head/head gasket.
Using a cylinder draw test can identify which cylinder is low and a
leak down test will identify the problem. As for the expense of the
equipment, you are correct but if you wish to do this type of work for
compensation you are expected to have the right equipment.
George Jefferson
:test or an amperage draw test. The amperage draw test is my preference.
:It is non-invasive, but it requires an engine analyzer. The analyzer
:kills the ignition while the engine is cranking and measures the
:amperage draw required to push each piston on the compression stroke.
cool. It seems though that this could only tell you relative compression.
You must have to do a real compression test on one cylinder to tell if
you have uniformly low compression
Also, I think you could do this quick and dirty by looking
at the battery voltage as you crank. Now if I only had a storage
scope..
--
george
geo...@mech.seas.upenn.edu