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Broken plug, threads only - remove head or pull engine?

F

fearnot

New member
1998 grandprix 3.8 no supercharger

Dad broke a plug off in the rear bank, only the threads remain.

My plan was to remove the rear head and repair it on the bench. I've heard a few people say that it's easier and cheaper to pull the engine to gain access to work on the plug hole.

If it turns out to be easier / cheaper to lift the engine we'd fill the cylinder with cotton, wax and grease so that we can drill and tap the hole while the head is still on the engine. I can scope the cylinder when done to make sure that it's clean.

I'd have to hoist the engine. I don't have a lift, so I can't drop the front end out the bottom.

Thanks
 


whiney said:
How to remove a broken spark plug embedded deep down in the engine block
If you follow the drill bit size that you need you just give the extractor a good smack into the hole and you will be surprised how much turning force you can put on it before it slips. Also heat up the remains of the spark plug, the plug will contract once it is cool so it will break the rust seal on it. Or at least we hope haha
Click to expand...

Thank you for the input. I'm familiar with removing broken plugs. The challenge is that it is on the rear bank against the fire wall. so the question was weather it was easier to pull the head off of the back or hoist the engine to work on it.
 
Disconnect both front dogbone mounts and put a ratchet strap somewhere on the back of the motor (at factory there is a hook somewhere near the alt) and connect the other end to the rad. support. Then just pull the motor forward thus rocking the backside away from the firewall. Keep in mind your downpipe is still attached and you may hit the tunnel if you pull it too far.
 
That would make life really easy. I am going to give the engine tilting a try and see how much room I can get.
 


Also..you won't need a 6" extension like that link. since your issue isn't down inside of the head like that Yota..you can use a shorter one. Heck..you could use a 3" or even a 1"
 
Success! I am so happy. Thank you for the suggestion of tilting the engine.

I had to disconnect the exhaust, remove the cooling fans and the air boot in order to be able to tilt the engine enough.

Then I had to remove the 02 sensor, that weird useless bracket on the back of the engine and moved the heater hoses to make room to work. None of this was difficult but took a lot time to figure out with strapping the engine back and forth about ten times.

Now I had lot's of room but could still not see the plug hole unless I stuck my head between the firewall and the engine. The ceramic was already gone because I started the engine earlier to blow out the ceramic core.

I heated the plug with MAP gas, hit it with PB blaster and cooled it with liquid c02 from holding a can of canned air upside down. I did this twice.

I made a sample of what was stuck in the block so that I knew what I was working with and could choose the best tool for the extraction. I purchased an extra plug and ran a hacksaw around it just below the hex. This leaves the taper seat and the threads. The ceramic core just pulls right out with the top of the plug. It was obvious that the metal was junk and that a #4 Easy-out was the tool that I could get the deepest and get a good bite. When using easy outs it's important choose the one that gets the deepest to minimize the chance of breaking it.

Now I hammered in a quality #4 EasyOut into the plug threads. Please don't use a cheap one unless you want it to strip or break.

Now the problem is how to turn the EasyOut with enough torque to break the plug threads loose because this will take more than it took to break the plug. The typical T handle tap holder will twist into a pretzel. Don't waste your time or your tool. It turns out that the square end of a #4 EasyOut is 1/4". The ratchet side of some 1/4" drive sockets fit on the end of the EasyOut and some don't. I found a 1/4" drive 1/2" 6 point socket that fit and then inserted a coupling nut (1" long threaded hex that has 1/2" OD) into the socket so that I could put a tool on it. There are other options but this one was the best way to get big tools on a little EasyOut.

It came out with no problem. Reassembly took about 45 minutes. I drove dads car back to him, smacked him and took my truck home.

I love it when things come together. Thank you again for a suggestion that saved me from pulling the head or the engine.
 
That's great to hear. I was hoping you could get to it by doing that. Sorry, forgot to mention about the fans/air tube. Figured you would notice that if you tilted it forward enough.

Hopefully you don't gain an exhaust leak at the downpipe. I've had a slight leak in mine since I dropped the motor back in. It seals up when hot so I haven't bothered to fix it yet.
 
I simply disconnected the down pipe. I had to in order to get the engine to pull far enough forward. Two nuts,takes 5 minutes, easy peasy and installed a new gasket. Tight as a drum.
 
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