Help, I'm driving a steam engine!

[braxtona]

On a trip up into the mountains last week my engine lost its normal throaty roar and started sounding like a old steam locomotive. After having the car towed, it didn't make it home under its own power, I did a little investigation.

The spark plug in cylinder #1 had sustained heavy physical damage. The electrode was gone and the threads were damaged as well.

So a few questions:

1) Anything I should do before pulling the valve cover and cylinder head to see what else is damaged?

2) Is it possible (or advisable) to pull the cylinder head with the engine in the car?

3) If I go to the work of pulling the cylinder head, should I just go ahead and rebuild the engine?

4) Any ideas for what would cause this?

[John Rogers]

When my engine did this it turned out to be a broken valve. If yours is the same a complete rebuild will be required. Hopefully it won't be. Good luck.

[WOODPIE]

For what it's worth, I had a spark plug blow it's electrode completely out the top a year or so ago on a freshly rebuilt 2.0 engine, all stock except for euro pistons. I was accelerating (or trying to) up a slight incline in 5th at about 3200 rpm. All of the sudden, POP! chuga-chuga-chuga. I nursed the car another mile or so to work, found the blown plug, ran a magnet end pencil down in and around the combustion chamber to see what I could find. I found nothing. I replaced the plug and have been motoring ever since. I can only guess that your electrode did not blast straight out, and therefore damaged the threads, and possibly other things. The choice between a total rebuild and simply repairing what damage might have occured in the one head would depend, I guess, on how many miles are on the engine. I think everyone here will tell you to drop the engine to pull one or both heads. I'm curious to know what brand of spark plug you had in there? Mine was a Bosch.

[braxtona]

Spark plugs were Bosch. I tried putting in a new plug to see what would happen. There wasn't any improvement. So I'm thinking the busted plug is a symptom not the cause.