Catastrophic Front Center Spark Plug Fail

[Drogers]

Hello


Catastrophic Front Center Spark Plug Fail (#5?)

Is there any Honda techs out there? Has anyone hear about this problem? Coil will not come out easy, plug shattered and will not come out engine blows by at spark plug hole.

Thank You
David

[rocky]

The ceramic of the plug broke? Have to assume the metal is still there. What's stooping you from getting it out.? Are you using a correct spark plug removal socket?

[Drogers]

I removed the front left and right no problem but the coil on the center came out hard and the socket will not go around the plug when you start the engine it has blow by in the plug tube.

Thank You
David

[krazykarguy]

Sounds like you did not get all of the coil pack boot out/off of the spark plug.

[rocky]

Please take pics of the coil pack (engine side) and spark plug/engine block. Concerned that you talk about blow by. .....

[94eg!]

Usually this happens when the plug is loose. In your case it seems the ceramic portion may have failed and the steel threads & nut are still in tight. Definitely get a flash-light into that hole and figure out what is obstructing your spark plug socket. If the ceramic is gone, then the rubber boot in the spark plug socket won't lift the rest of the plug out. You may need help from a magnet or something to pull the rest of the plug out. Either way I would expect debris in the combustion chamber which...

Perhaps you can use a small vacuum with a bendi-straw & duct tape to lift bits out of the plug-hole before trying to finally remove the plug? Either way, be sure and get everything out of the plug hole before removing the plug.

[carguy07]

I think he has the failure that ruins the head (might be able to repair it) when a plug backs out and combustion gets past the threads and destroys everything, coil, plug and threads in the head.

[rocky]

Carguy08 and 94eg! remind me that the head has to come off. There may well be debris in the cylinder that has to come out.

Once the head is off, then you'll have access to the complete mess.

[Drogers]

I was able to grab the top part of the electrode with long skinny needle nose(it was bent 90 deg.)and break that off then I made a small chisel so for four hours it was chip chip vacuum chip chip vacuum. I was finally able to remove the plug then cleaned with a long magnet and vacuum both all the way into the combustion chamber. The only problem now is there is no threads for the new plug

David

[94eg!]

Spark plug threads are not your "only" problem. But you can always have the head repaired with a heli-coil or something else.

Are you sure the threads in the head are stripped? The threads on the damaged plug look pretty normal (just dirty).

Either way I think that cylinder head is going to have to come off. It's not terribly difficult to do, but it does require a lot of gaskets (whole intake manifold has to come off) and new Honda Type2 coolant.

[harley909]

How do you know there are no threads for the plug?
I would sure try to thread a new plug or a thread cleaning tool into the plug hole...carefully and with some oil on it before I came to the conclusion the threads are buggered.

Pulling and replacing/repairing the head is a whole lotta work to go through if it turns out the threads are still good.

[krazykarguy]

I don't see the ground electrode on the destroyed plug. That's bad news.

[rocky]

The head has to come off, the cylinder cleaned of all debris. The head needs to be checked for damage as well.

Surprised that not only the electrode is missing, but also the washer. If it came out without a washer, then I suspect that the plug was making contact with the piston....

Which just makes a bad situation worse....Damage to the piston will require the engine to be pulled and stripped. Then rebuilt

[harley909]

The questions is,
Was the motor(piston) making any noises at the time that all this occurred?

As for the ground electrode, I would suspect it may simply have disintegrated...and if not, it's stuck along the side of the piston and is going up and down..and the cylinder wall/piston is damaged.
The other issue is whether or not the piston whacked the plug...and in fact this may be why the electrode is missing/broken.

The ultimate fix is to tear the motor apart and have a look as Rocky said.
The next best may be to do a compression check on that cylinder, providing you can thread the compression fitting into the spark plug hole (it may well serve to help clean out the threads anyways)
The last and least attractive option is to try an put a new spark plug in (carefully threading it in) and hope for the best...and see what happens.

To be honest, I would not want to be in your shoes...it's a bad situation.

[theirishscion]

The key word here is boroscope. Fix a mechanic (or doctor friends or whoever) with access to one and take a good look inside that cylinder (you'll need to turn the engine to get the piston to the bottom it it's travel if you want to see the whole cylinder). If the piston surface is obviously damaged and the cylinder walls are badly scored up, you're in trouble. If not, and if that cylinder passes a compression test (showing the valves are still sealing) then with any luck the spark plug electrode was mashed up and ejected through the exhaust valve nice and quickly. If you want to find it, look in the top catalytic converter for that bank, it'll be looking up at you from the top of the honeycomb (don't actually do this, I'm just saying that this is where it's likely finally come to rest). If you want to optimistically skip the boroscope testing, and it turns out that you do still have some threads in the head, put a $20 compression tester on the cylinder and compare it to it's neighbors. If it's close-ish, then bang a new plug in and hope for the best, I'd say (possibly with a helicoil if necessary). I think you're unlikely to do any more damage to the engine in doing that, even if it doesn't last for long.

If you can get it running again by doing this, my next (somewhat morally reprehensible) step would be to trade it in against something that isn't a time bomb (unless of course the boroscope showed no damage at all, and the threads end up being substantially unharmed.

Keep in mind that helicoils in an aluminium cylinder head, if done right and by an experienced technician, are usually considered superior in strength to the original threads (since it's a steel plug threaded into a steel helicoil, threaded in a much bigger, coarser threaded hole in the aluminium head)