Spark Plug Trouble!

81SCRosewood · 81SCRosewood's Garage

I am replacing the spark plugs for the first time since buying the 81 911SC. I am on the third spark plug and can NOT get it out. I have been spraying PB Blaster for a few days and still it's not moving. Actually at this point, I am surprised the plug has not snapped with the amount of force I've applied.

Today, another local Porsche owner recommended rotating the force to remove and install back & forth to help release it. Another owner said to run the engine for 1 minute to heat and expand the area and then try removing it.

Anyone else ever deal with this scenario. If so, what was the solution?

Thanks for any and all suggestions!

lucittm · lucittm's Garage

Rosewood,
Is the plug loose at all? If not, the PB Blaster will not help because it won't be able to get past the sealing ring. My recommendation would be to leave the plug in place until the engine is overhauled and then attack the problem from the combustion chamber side.

If it is loose, I would forget the lubricant because you have galling between the head and the plug where some of the metal has transferred from one surface to the other. It is, in effect, cold welded. This can be caused by corrosion or over tightening without any lubricant and it is assisted by the heating and cooling cycles.

In the Navy we experienced this quite a bit with similar (mostly monel) and dissimilar metals. If we could get to the threads, we soaked them in a mild acid overnight. Coca-Cola Classic (carbonic acid), strong Kool-Aid (citric acid), vinegar (acetic acid), or even iodine (hydriodic acid) worked well. The idea is to get the acid to break the bond between the metals by dissolving the weaker metal. In this case it will attack the aluminum. Once you get the plug out, be sure to chase the threads and then apply lubricant to stop the acidification process.

If the plug is really loose, but gets jammed after 3-4 turns, you might have corrosion or carbon buildup on the last threads. Try adding some Techroline or Berryman's B-12 Chemtool to the gas and then try it again. This doesn't seem like your problem though.

Good Luck,
Mark

81SCRosewood · 81SCRosewood's Garage

I thought I had managed to back it out about one to two threads. But your point about the PB Blaster not getting to the threads because of the crush washer has me wondering now.

Thanks for the education on this topic. I'll move on to the rest and see what I encounter.

Question: what about the idea of running the engine for one minute to heat and expand the threaded area?

lucittm · lucittm's Garage

I think heating the engine is a good idea because it doesn't cost you anything and it can do no harm. I would try a gentle heat for about 1 minute. If that doesn't do any good, get it really hot, and try that. If that doesn't work, you know it's really stuck.

Good Luck,
Mark

super_dave0069 · super_dave0069's Garage

I had one stuck and the warm/hot engine trick worked for me.

81SCRosewood · 81SCRosewood's Garage

Thanks! lucittm & super dave,

I'll try the gentle heat for a minute method this weekend.

Rich

Pazuzu · 12-20-2008, 09:53 PM

I had 1 plug get locked up on my last change, the rest came out with fingers only.

I finally bit the bullet, and put a 1/2 inch breaker bar on that one, and cranked it out (sweating and cursing) 1/6th of a turn at a time. I was sure it would be liberally coated with aluminum threads.

Nothing. Nothing at all. Not a mark on it. Some little piece of carbon got between the threads, and the Porsche heads are such tight tolerance, that it caused enough tension as to lock up the plug. The new plug went in smooth as silk.

What I'm saying is, sometimes, you just need to beat on the engine, despite what you and others might think. If the head is galled, and you got it to turn at all, you've already done the damage. Now's the time to get it out of there by any means possible, and assess what is left. Worrying about what's going on AFTER locking up the plug won't get you anywhere.

diverdan · diverdan's Garage

That reminds me of a visit to Luigi Chinetti's Ferrari shop on 13th Street in Manhattan back in the late 60s. There was a bright red berlinetta with a stuck oil plug in the aluminum oil pan. The Italian mechanics solution was an 8 foot long pipe on the wrench. Wonder if that 's a standard ferrari tool ? Good luck! (I believe the owner of the car was a priest!)
diverdan

diverdan · diverdan's Garage

To prevent the problem with spark plugs I use graphite either liquid or solid pn the plug threads. Any reason I should or shouldn't switch to something like Coppaslip. I think the reason for the graphite has to do with conductivity.

diverdan

dshepp806 · dshepp806's Garage

Quote:

Originally Posted by diverdan

To prevent the problem with spark plugs I use graphite either liquid or solid pn the plug threads. Any reason I should or shouldn't switch to something like Coppaslip. I think the reason for the graphite has to do with conductivity.

diverdan

+1 on the graphite ....

Best,

Doyle

81SCRosewood · 81SCRosewood's Garage

Running the engine for about 1 1/2 minutes did it!

Now, is it best to wait for the engine to be stone cold again before installing the new plug?

THANKS!

Rot 911 · 12-22-2008, 05:08 AM

Quote:

Originally Posted by 81SCRosewood

Now, is it best to wait for the engine to be stone cold again before installing the new plug?

Yes! You don't want that aluminum cooling down and contracting around the new plug. Wait until cold and then reinstall.

RoninLB · 12-22-2008, 07:45 AM

I use Loctite Graphite-50 on my plugs. If you read the can it says for spark plugs.

It doesn't say that on the Loctite Copper or Loctite Nickel cans.

81SCRosewood · 81SCRosewood's Garage

I've always read not to use any lubricants on the spark plugs for these 911's. But, after this experience ... it's got me thinking about it. I've read up on this Graphite-50 stuff you guys recommend and it sounds like the best way to go.

So, no worries about the plug backing out like I have always read?

T77911S · 12-22-2008, 08:28 AM

would it be a good idea to run a chase or tap in the plug hole? or would the shavings be a risk?

db_cooper · db_cooper's Garage

I put a drop or two of engine oil on the threads and install the plugs. Works well for me for thirty years.

Don't run a tap though the plug hole. Could cause more problems (shavings dropping in or nicking a valve). I would inspect with a mirror and light.

Probably, plug was over torqued and the threads were seized. Warming expanded the head and released the plug.

Use a torque wrench if you have any doubts as to how tight to install the spark plugs.

mossguy · 09:10 AM

Quote:

Originally Posted by db_cooper

Use a torque wrench if you have any doubts as to how tight to install the spark plugs.

Always a good piece of advice!!

Tom

Edit: 18-22 ft/lbs according to Wayne's book.

Best,

Tom

RoninLB · 12-22-2008, 09:08 AM

Quote:

Originally Posted by 81SCRosewood

I've read up on this Graphite-50 stuff you guys recommend and it sounds like the best way to go.

So, no worries about the plug backing out like I have always read?

I've never had a problem.

I use it lightly and keep the 1st two threads clean.

disclaimer: the popular product most guys use is copper anti-seize