<snip> If your reading anything under 100psi, you've found the problem.
Not necessarily so Gary. You're not looking for a minimum pressure reading
so much as you're looking for relatively equal readings on all cylinders.
Now if all cylinders are at 50 psi then I start looking for a hole in the
engine somewhere. The FSM should list the tolerance range for engine
compression. A new engine may read 125 psi +/- 3 psi on all cylinders for
instance and that same engine with 200K miles on it, even if it has been
well maintained, may read 98 psi +/- 5 psi on all cylinders. Does this mean
this engine needs major repair or rebuild? Not in every instance. If all
other diagnostic data point to no major problems then is it worth the time
trouble and expense of removing and rebuilding or replacing the engine?
Probably not. Now if we take the same engine and do the same compression
check and find 5 cylinders with 98 psi +/- 5 and one that has 70 psi then
we've found the culprit in that cylinder. However more diagnostic is needed
to determine the cause of the low reading and probable repair.
Ray Irons
Dover, DE
This archive was generated by hypermail 2b29 : Fri Feb 06 2004 - 11:47:02 EST