I had a tapping noise start today, so I wanted to check the spark plugs to see if any of them are foul. 59K on the engine, 1K with the SC. Never over-revved.

Cylinder 4's plug was loose, did not need any force to turn it. When it came out it had oil residue on the threads and the tip was crusty brown.

Cylinder 3 was perfect. Maybe a tiny bit loose, but still came out like it should and looked fine.

I cannot get cylinder 1 or 2's spark plug out. I can turn them about 1/8 turn, with moderate force, but then they are seized. I dont want to force them out, even though I have put a little muscle.

Anyone had this problem? I searched and no one posted anything like this.

What would cause this?

How can I get them out? Should I force them? I am scared I will strip the threads.

 

I can only guess they were not properly torqued the first time. Have you tried removing them when the head is different temps i.e. hot, warm, cold?

 

I let the head cool for an hour, and tried again. Moved a little more. the head is still hot, so I will wait for it to be cool before I try again.

 

Tried again this morning with the engine cold. Plugs still will not turn. Is it possible they backed out a little, then the engine vibrations crossed the threads? What else would cause this?

 

Engine vibrations don't "cross" threads.

There's a good chance whoever put them in orignally cross-threaded them instead of putting them in correctly. Either that or they forgot to put a release compound on them before installation.

Btw, don't try to remove spark plugs when the engine is hot. Metal expands with heat making them tighter.

 

ok if the threads are crossed, how do I get them out without damaging anything?

 

I would use a penetrating oil such as lockwrench. Apply it to the plugs in question. Next, you say that you can turn them out but then they seize...so turn them back in a bit (tighten) and then back out and repeat that sequence, letting the oil work its way into the threads and see if that helps...if not, i don't know...

 

^^^Thanks, I will try that.

 

One other thing I someone told me might have happened...The plugs could have got so hot that they melted (from detonation, although I have not heard any and my a/f ratios are safe). This is from a chevy guy that has seen plugs melt before. Could this be the case?

 

I would say that anything is possible. You'd have a better idea of what happened when you get them out, of course. I would take a guess that crossthreading is more likely than melted plugs though.

Can you take pics of the first two plugs that you took out so we can take a look at them? I know you said that the one looked fine and the other was crusty brown but just in case post em up for us.