Compression in no. 3 cylinder 15psi! Help Please

[nlink720]

Engine started running roughly. I removed the new (week old) platinum 2 spark plug from the suspected no. 3 cylinder and it was damaged. The white insulator part was gone.. broken off into engine. I replace the plug, but the engine still runs on 3 cylinders. I did a compression test today, and the cylinders were as follows: 180-180-15-180.

I now suspect cylinder damage, or maybe a valve that is being held open.

Does anyone have any ideas?? car ran GREAT until this happened.

Thanks :idea:

[quaddawg]

Did you pull the valve cover to take a look? Do that, and if the rockers on that one are OK, then you are going to have to pull the head and check it out. Doesn't sound good though... with the damage to the plug, sounds like something came loose, or got sucked into the cylinder...

[jglutz]

If the cylinder is shot...it can be verifed by removing the spark plug wire when the engine is running. If the engine perforamnce does not change...yeah it's that cylinder (poor man's compression test)
Any loud noise comming from the engine?
I would also start with removing the valve cover and looking at the valve train...simpliest thing to start with.

Try to look at the symptons/evidence this way.....did something cause the plug to break (a dropped valve)..or...did the broken plug break something (rings)

Your not going to find out with out some level of tear down.

[nlink720]

I appreciate the help... I will remove the valve cover tomorrow and take a look at the rockers, etc. It would be nice if were something simple under there.

I will also do a wet compression check to see what that yields.

The engine runs roughly, but is not abnormally loud. Runs as only three cylinders are firing. (I determined it was cylinder 3 by initially removing the spark plug while running, and there was no change.) I then proceeded to investigate ignition issues and fuel issues, but after doing the compression test, I know that cylinder 3 will not fire until I figure out how to get the compression back up to semi-normal figures.

Thanks for the ideas and help so far!!

[nlink720]

Valve Job Complexity

OK, so I did the leak down test, and nothing changed... so I know that one of the valves is bad. I am fairly certain that the head gasket is at least in adequate condition.

My question is: How difficult is it to replace an intake or exhaust valve. I normally wouldn't attempt this, but the B3 engine is so small - can't be that hard right??

Not sure if it is the Exhaust or Intake valve, as I do not have compressed air to do a leak test.

Thoughts??

[dahodges]

Its not hard to change a valve. You do need a spring compressor. If the valve seat is still good, a little lapping compound and it will be good as new.

[nlink720]

Thank You all