Spark plug removal - aluminum heads?

Remove warm if they are tuff to get out and when you install them warm or cold, recheck them for tightness after a couple of heat and cool cycles.

----------------- The SnoMan

is it best to only mess with aluminum heads when cold?

same on intake... I've had the pleasure of pulling out some threads on an aluminum intake one time when the engine was warm.

I felt the $$ floating away about the same time...

----------- Elbert snipped-for-privacy@me.com

COLD.

The hole can "oval" if the head is hot with nothing in it.

Not really because aluminum expands fars the stell when heated so the hole size will grow quicker than the plug does.. If you have had problems with threads coming out it is because either there were to loose and leakge burned and gummed up thread so they strip or they were over tightened when they were installed.

----------------- The SnoMan

dead cold. overnight cold.

Agree with cold only. Be sure to put a dab of antiseize compound on the threads and be careful not to overtighten.

Hot or cold will work as for reasons stated earlier in thread. It is important to recheck them for torque after a few heat/cool cycles though.

----------------- The SnoMan

I love this one. you are kinding right? If it was going to "oval" it would if plug was in there or not. Aluminum is stable and predicable, it just has a different expantion rate the steel/cast iron.

----------------- The SnoMan

Ditto with VW since at least the forties. Many people have removed plugs from hot aluminum heads and lived to regret it.

Dave

I work for an aluminum cyl. head mfg, we recommend cold, warm if you absolutely must( in a racing situation between rounds or heat races) be SURE to use a good ANTI-SEIZE on the threads.

Same thing with Harley Davidson. Especially important if you have had a Heli-coil repair to a plug hole. A hot plug will take the Heli-coil out with it.

- Regards Gordie

That is because the aluminum block expands quicker and more than insert which expands at same rate as plug. But if the helicoil is sizeed propelry and inserted in head when it is hot so that it shrink fits around helicoil, this will not happen. Blame this problem of the individual installed the coil, not the head or its content. It is still best to remove plug for a normal aluminum head will it is warm.

----------------- The SnoMan

No I am not kidding. The chances of it actually happening are probably only slight, but that is what they preach. The reason being that (as you have already pointed out in previous posts) that aluminum expands at a different rate than iron. An engine is assembled and torqued cold. As things heat up the head has all kinds of push/pull stresses forced upon it. Which is fine, the engineers have designed it to handle this. But when you take out one simple spark plug, you have changed the structure.

Every engine head does distort a little when assembled so there is no aurgument there but at what point is it a issue. THe hole may disort by .001 inches or so from being true round but I would not cal it oval shaped. Aluminum heads bolts to a cast iron block are usually pretty reliable if properly torqued and not over heated as the bolck helps keep them in shape so to speak.

----------------- The SnoMan

On Fri, 7 Jul 2006 22:42:54 -0600, "Chevguy"

If I may interject some information. I posted the original question about aluminum heads and spark plug removal. The answer that SnoMan gave to me was to remove the plugs with the engine COLD but if there is any problem then WARM the engine up. There was no mention of bringing the engine up to operating temperature.

SnoMan's answer was simple and concise and as far as I am concerned it is also the most logical.

I thank everyone who showed an interest in the question.

A.J.

All kinds of answers for a simple question. But a important step was only touched on once. Once you get them out and are reinstalling be sure to use antiseize on them. A good metal based antisieze, preferably nickle or second best copper. Don't be afraid of it but be sure not to get any on the electrode. Next time there will be no problems. Also just as a side note. Use good quality platinum plugs, your choice. I prefer Bosch but OEM are great also. Just pulled the plugs out of my wife's Pontiac Montana with 65K. Measured gap and it was @ .062. .060 is factory setting. They were factory platinum.

I would also add to be sure you don't get any on the insulator, either.

Next time there will be no problems. Also just as a side note.

With modern engines, using what the factory used is always a good choice. Anything else can be a crap shoot, in my experience.

Dave