spark plugs are realy tight

[lagbolt]

I havr a 91 and I can't get the plugs out. Im afraid of breaking them. Any advice?

[Pu241]

Fire up the car and let it get warm, not hot warm..
Then spray them with BP Blaster® using the red tube to deliver it direct to the threads.
Let soak and spray them again.
This generally, works well.

[Twistiva]

Fire up the car and let it get warm, not hot warm..
Then spray them with BP Blaster® using the red tub to deliver it direct to the threads.
Let soak and spray them again.
This generally, works well.

So why do you let the engine get warm, but not "hot warm"? The warmer temps should expand the spark plug body/threads but wouldn't the warmer temps also expand the block more, too?

[Aaronbrook37]

So why do you let the engine get warm, but not "hot warm"? The warmer temps should expand the spark plug body/threads but wouldn't the warmer temps also expand the block more, too?

Penetrating fluid can produce pretty noxious smoke if it gets too hot. The spark plug is not made of the same material as the aluminium cylinder head, which is why the slight amount of thermal expansion is desirable.

[lagbolt]

Ok I hit it with some penatrator spray. How long do I need to let it set in before trying again?

[Aaronbrook37]

Shouldn't need too long. While you're waiting, feel free to ensure the fluid is getting there by tapping lightly on your socket extension with a hammer.

[koRnhead]

This is why you use anti-sieze on spark plugs!

[Pu241]

And oddly enough, I find first attempting to tighten the offending plug/bolt/nut tends to work better.
But you need to take care and not snap it, just want the tinies bit of movement.
Then try loosing it.
Once it breaks loose hit it again with the PB Blaster® and working it alternately tighter and lose.
Remember the head is aluminium and the plug body is steel.
You do not want to gall/crossthread the threads in the head.
Much badness when that happens.

BTW, yes noxious fumes are part of it, getting burned is nother part, but mostly the expansion rate of aluminium is larger than that of steel and so does not require as much temp to get the expainsion differential you are wanting.
Reiterate the use of anti-seize upon plug install.
Good luck!

[lagbolt]

Got them out thanks guys!

[Twistiva]

Penetrating fluid can produce pretty noxious smoke if it gets too hot. The spark plug is not made of the same material as the aluminium cylinder head, which is why the slight amount of thermal expansion is desirable.

And oddly enough, I find first attempting to tighten the offending plug/bolt/nut tends to work better.
But you need to take care and not snap it, just want the tinies bit of movement.
Then try loosing it.
Once it breaks loose hit it again with the PB Blaster® and working it alternately tighter and lose.
Remember the head is aluminium and the plug body is steel.
You do not want to gall/crossthread the threads in the head.
Much badness when that happens.

BTW, yes noxious fumes are part of it, getting burned is nother part, but mostly the expansion rate of aluminium is larger than that of steel and so does not require as much temp to get the expainsion differential you are wanting.
Reiterate the use of anti-seize upon plug install.
Good luck!

Thanks for the explanation, guys! Definitely good to know.

[denguy]

Glad you got them out OK. Years ago ,1995, I was going to change the plugs in my recently purchased used 92 Festy with about 50K miles and one snapped off in the head while barely touching it. The body of the plug had badly rusted plus the threads were frozen in the hole. After trying the usual PB blaster and EZ outs, I ended up taking the head off, drilling thru the plug almost to the threads, making four or five cuts thru the threads with a saber saw blade, then prickpunching out the pieces. Probably ought to take out the plugs once a year, check for rust, and apply fresh antisieze compound .

[WmWatt]

Yep, an annual tuneup is a good idea.

[jawbraeka]

Are the spark plug at the max?

Ill say if you have a tiny bit of thread left, you could get away with going forward (tighten) to "crack" the plug a bit and then go back (loosen)

But by the way you're talking, sounds like they're tiiiiight.

Sent from the depths of hell.