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I wanted to install new spark plugs today. I managed to do 3 of the 4, but the 4th is seriously stuck. I have the appropriate tools, but that 4th one feels like I would need a hex-driver handle about 3ft long to get enough torque to dislodge it.

Any ideas about what I might do to loosen it, aside from bringing it to a garage and asking them to change one plug?
 

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Garage is just going to reef on it.
 

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Penetrating oil (I use liquid wrench), for an hour at least, prefer overnight. then the long handle. Put a tiny bit of anti seize on the base of the threads when you reinstall (just a bit, god know what happens with that stuff in your heads. About 10 bucks at CTC a bottle lasts years.
 

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And I have a breaker bar if you need it, about 2 or 2.5 feet long. It is a half inch socket, but I have an adapter for the smaller sockets as well.
 

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Breaker bar is likely to twist the plug in half and leave some of it in the threads and then you have a real mess.

Try penetrating oil over night - start the motor and get it hot then gently try to loosen the plug.

If that doesn’t work take it somewhere and let them deal with the mess if the plug breaks.
 

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Breaker bar is likely to twist the plug in half and leave some of it in the threads and then you have a real mess.

Try penetrating oil over night - start the motor and get it hot then gently try to loosen the plug.

If that doesn’t work take it somewhere and let them deal with the mess if the plug breaks.
Yeah, agreed, that is a possibility.
 

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Aluminum heads? It may be seized. What is the car/engine? That will help us give you more specific advice.

The first thing I would try is to connect everything back up, start the car, get it warm, shut it off, then immediately try and get the plug out.

Last one I had at the school shop that twisted off the hex (leaving the threads in the head) we had to send out. I couldn't get it with an extractor, it wouldn't bite hard enough. The place had a special extractor for broken plugs, it was out in a minute.
 

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Aluminum heads? It may be seized. What is the car/engine? That will help us give you more specific advice.

The first thing I would try is to connect everything back up, start the car, get it warm, shut it off, then immediately try and get the plug out.

Last one I had at the school shop that twisted off the hex (leaving the threads in the head) we had to send out. I couldn't get it with an extractor, it wouldn't bite hard enough. The place had a special extractor for broken plugs, it was out in a minute.
Or like a broken wine cork just tap it through and it'll come out the exhaust pipe when you start it up ;).
 

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Try penetrating oil over night - start the motor and get it hot then gently try to loosen the plug.

If that doesn’t work take it somewhere and let them deal with the mess if the plug breaks.
Happened to me once. Found a can of Blaster in my garage. Left that stuff on overnight, started the engine the next day for a few minutes and managed to remove that dang plug at last.

I had thought about using anti-seize compound (Loctite), but I recalled one of the older boys in my high school recommended using penetrating oil to get stubborn spark plugs out.
 

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Son did some youtube research, found a good test on penetrating oils. Best one was the seafoam brand (ya, surprised me too).

Goop it up good a couple nights, warm it up, try a socket/breaker bar and snipe(if necessary), try not to break/crack the plug or you may be pulling the head. A possible problem with this advice is you can also pull the threads out of the plug hole (alum or like heads, this was always a concern with a/c).
"should" you pull the threads out look up, "helicoil". Thread it in, thread in the new plug and you're stylin'.

Wish I could be more help, have no idea why automotive mfgrs/places don't use threadlube, aviation's been using it since the 40's because it works.
 

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Yeah changing plugs, setting up carbs and reving the snot out of it to set total timing just ain’t as much fun as it used to be. I can barely get a box end sideways onto the number 8 plug because of the fuckin headers.
 

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Seafoam is great stuff as mentioned. Try PB Blaster. Seized steel to aluminum is a bitch.
Nothing wrong with a smallish handle extender as long as you have a good socket on it and trap the tube so it doesn’t slip off. Steady pressure.

Someone mentioned warming the motor up slightly. There’s a product available by Wurth called Rost Off which comes out of the can and at very cold temps. You could use a product like this as long as there’s a rag over the porcelain to try and “shock” the metal base of the plug.

A similar trick I use is taking a torch to gently heat the hex head or nut and quickly quench it with water in a squirt bottle. It creates quick contraction which can break a freeze on a seized fastener. I have saved hundreds of 50 +year old fasteners from breaking this way

You run the risk of shattering the porcelain on the plug with either method but if you don’t care or it’s already broken, this will certainly get the metal section out. You may have to heat and quench a couple of times
 
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The other thing about spark plugs is when you go to tighten them up. There are torque specs for each individual car/motor. Like my Celica I discovered is 12 lbs.
You get too much you get too high
(you get too much you get too high)
Not enough and you're gonna die (gonna die)
 

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Yeah you just snug them in with a bit of anti seize or you can spec them if you have torque wrench that is accurate as low as 12 lbs.
 

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Another thing with stuff like brake line fittings I’ve found is that once you crack the thread with heat or whatever and it starts to move say 1/8 of an inch rock it back and forth with the wrench and it gradually starts to travel more and there’s less chance of twisting the line than if you just reef on it once it starts to move.
 
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