Cylinder has only half compression

[regalrobert]

I have a 2000 Regal (daughter's school car) that is missing on one cylinder. She had it tuned up, but the mechanic said she has only about 50% compression on one cylinder. It is not using (or burning) any oil.

Going over likely causes, burned valve, timing jumped, etc. are what come to mind.

Any suggestions to help diagnose further? 5 cylinders had about 95 lbs compression and one had 50 lbs.

The engine is an OHV 3.8 L 6 cyl.

[stripe]

Originally Posted by regalrobert

I have a 2000 Regal (daughter's school car) that is missing on one cylinder. She had it tuned up, but the mechanic said she has only about 50% compression on one cylinder. It is not using (or burning) any oil.

Going over likely causes, burned valve, timing jumped, etc. are what come to mind.

Any suggestions to help diagnose further? 5 cylinders had about 95 lbs compression and one had 50 lbs.

The engine is an OHV 3.8 L 6 cyl.

do you mean percent?

Cheers
Stripe

[regalrobert]

Either way. It is only getting about half the compression of the other 5 cylinders.

[stripe]

Originally Posted by regalrobert

Either way. It is only getting about half the compression of the other 5 cylinders.

95 lbs compression is very low that is why I asked.

Cheers
Stripe

[BNaylor]

How many miles are on this engine? I agree 95 lbs is way too low. I normally see 125 psi and up.