stuck spark plug

Have a very stuck spark plug on a 350 Crusader. Took out 3 of the 4 plugs on one side of the engine. The #4 plug is stuck hard. Have been flooding it with PB Power Blaster penetrating oil all week. Tried last night to free the plug. Still stuck. More BP sprayed. Thinking of trying a small impact wrench. Feathering the trigger to try and bump it around. Any suggestions????
Thanks in advance.
Jim

my personal experience, drive the machine to the normal hot, remove the plug as soon as this helped me, it opened easily even if the cold did not open.

Greetings,
Mr. j. I would hesitate to use ANY power tools at this time. Better mechanics than I might have some tricks but I would be surprised if they involved anything other than HAND tools.

SBF (sheer brute force) does work on some occasions when ALL else fails but I've had my share of "Oh snap" (see what I did there?) moments and 99% of them evolve because of impatience, frustration and power tools.

You may already have done this but you're supposed to tap on the plug (with a hammer) while you're spraying the PB blaster so it penetrates better.


There is a product available at some auto parts stores that freezes (and shrinks) the part in combination with being a penetrating oil. I used this not long ago to free a stuck shower arm in my home (I didn't want to have to break into the wall).


The trick to using this product is to use a lot (really a lot) so it actually cools the plug and shrinks it. I probably used a third of the can. Try to get it on the metal part of the plug and as little as possible on the head. The idea is to make the plug smaller so it will break loose and come out.


The impact wrench might work or it might make things worse.

Go on to old car sites. Yours is not the first stuck plug. Somehow, real mechanics can finesse rusty bolts that the rest of us cannot.

Good news is that the head is cast iron and the plug is steel. (I took the threads out with a spark plug on an aluminum VW head and got to replace the head for my ill fortune.)

Can you run the engine and get it nice and warm before trying the plug again?

Just be sure you are turning it the correct way.

Don't ask.

I have found that an impact wrench almost always removes a stuck plug, nut, bolt without damage, but hand tools often ruin the threads or bolt. Even rusted bolts, in place decades, come out easier with an impact wrench. When disassembling a really old engine, a wrench twisted off the bolt head, but the impact wrench backed the rest out flawlessly. Rental stores have them.
Tapping the end of the plug while wrenching might work, but it's easy to break the plug. Also a light acid, applied to the threads will eat enough rust to sometimes free threads.

Try tightening a smidgen first, then loosen.

I have also found the longer the breaker bar with less force seems to always beat shorter with more.

Ignoring physics of course....

I would run the engine to heat the block then hit the plug with cold spray.
Warming expands the female threads and cold shrinks the male threads.
Is it just me or did that sound sexual? I've got a dirty mind.

You know who will yell you....

If plug is not misfiring, good argument to just leave it.

Heating up engine is a good idea.

Tapered seat plug, so break away torque can be pretty high.

If truly seized, you could break it off. Hard to tell how much torque it will take before breaking.

Be sure to use a 6 point socket for spark plugs not a 12 point that might round the plug.''

The better (tighter) the fit the better your chances.

A long breaker bar under tension , hit with a hammer can produce good instant torque .

Good luck!

Saturday...bought a new quality spark plug socket, had a long handled ratchet and slowly applied some torque to the plug. It disintegrated. All the porcelain guts came out of it including the metal nut head of the plug leaving the threads in the head. Today will heat up the head with the torch(manifold and other plugs are removed for room to work cant start engine) tap in a #5 square ez out and give it a turn. Keep your fingers crossed. Cant remove the head. Three of the bolts have lots of corrosion on them (52 year old boat). The bolt head will twist off if I try. If all fails.. Time to pull the motor and replace it with a new one. Silly to reinstall an old motor after the trouble of removing it.

Greetings,
Mr. j. Aw...snap. I feel your pain. IF you're unsuccessful in removing the remains of the plug, you might want to try to remove the head before you pull the motor. You never know. Are they bolts or studs with nuts holding on the head? I'd heat up the nuts, if so equipped, first and douse with penetrant before trying to remove them.

Since you might be removing the motor anyway, what have you got to lose?

Any way to drill it out a hair clean the threads with a tap? You risk getting junk in the cylinder though.

Can't you punch the rest of the ceramic insulator down and into the cylinder? You won't be able to drill the ceramic. Then you can use the largest Ezy-out that will fit within the metal remains. Two serious negatives: 1, the junk in the cylinder; some will certainly end up in the space between the piston and cylinder wall. 2, the Ezy-out will be working hard to spread the remains tighter within the threaded hole.

I'd vote for pulling the head and risking the studs/bolts first. You will only be left with using the Ezy-out on broken studs/bolts. And, you will be able to clean the cylinder had you been adventurous enough to try the cure on the broken sparkplug.

I'd bet that the cylinder head bolts are not particularly hardened so if you break one or two you'll be able to drill and use Ezy-outs on them.

War stories for encouragement: An exhaust manifold stud broke on my '83 Volvo Turbo in about 1991 with about 160k miles on it. I disassembled the manifold and turbo to get at the broken stub. The studs were hardened but I was able to buy a suitable drill bit. Broke the Ezy-out. Had to take the car to a real mechanic who set it right. I did the brakes on my 1959 Studebaker Hawk in about 1974, broke the bleed screw on a slave cylinder, broke the Ezy-out in the bleed screw. No replacement slave cylinders to be had in Montreal. Took the cylinder in to McGill University's mechanical engineering lab and the old German technician 'popped', arc welded, a bit of welding rod on to the broken bleed screw and it wound out easily. The car's long gone, but I've still got it the bleed screw.

Breaking taps is much worse!

If you can get the remainder of the old plug out even with minor damage to the head, there are taps for cleaning up the threads or worst case helicoil and other brands of repair products for the hole. The trick as mentioned above will be to prevent or remove after all the shavings from the cylinder before starting it up. Vacuum tubes and skinny magnets are very effective. I had to do this many years ago on a car and the helicoil worked great. Still have the kit in my tool box.

Success.....had to reset and drive in the square drift/ez out until it held firm on the fourth attempt with a half inch drive large ratchet and fair amount of force it popped and started to move then unscrewed. Wow relief. Got my new manifold and elbow delivered yesterday. Time to put it all back together. The manifold looked good however the elbow was very restricted. Just going to change out both. Thanks for the ideas.
Jim

Greetings,
Mr. j. Were you able to clean the cylinder out? As was mentioned, there is a potential for bits of metal and ceramics in the combustion chamber. Any way, good for you.

Will try to insert a small hose attached to a vacuum.

psneeld said:

Try tightening a smidgen first, then loosen.

I have also found the longer the breaker bar with less force seems to always beat shorter with more.

Ignoring physics of course....

Click to expand...

jclays said:

Will try to insert a small hose attached to a vacuum.

Click to expand...

This may be a good time to buy one of the little video cameras with built in monitor and the camera on a flexible wire. Harbor Freight sells them.

Greetings,
Mr. WK. The HF unit I purchased would not fit through the spark plug hole. I think there are much cheaper units that plug directly into a laptop with smaller ends but I don't think Mr. j need go to that expense.

IF there is crap in the cylinder and it DOES cause problems down the road he might end up doing what he was willing to do if his recent wrenching had not been successful. Replace the engine.