Posted by John on April 10, 1998 at 22:29:56:
In Reply to: Valves - what are the symptoms of bad valves? posted by DG on April 10, 1998 at 20:56:02:
I dont know what make of engine you have, generaly compressions are slightly higher than 95psi. You need to establish what you're compression should be. Offhand I'd say you're valves are okay, I say that because all of your cylinders compression's are the same. If you have a bad valve it would show up as a 20-30psi difference between your cylinders.
When you do a compression test you need to do a "wet & dry" test.
For the "dry" test install your compression gauge and spin the motor over with the starter, record your readings.
For the "wet" test squirt some 10-30 oil ('bout 2 table spoons) into the plug hole. Take another compression reading.
If you see a reading increase, this means your rings or cylinder is slightly worn. (The oil acts as a seal around the piston to simulate an ideal fit)
Worn pistons can lead to oil burning or fouling of the spark plug.
Hope this helps!
: Can anyone tell me what they know about valves that my
: be going bad. I have a tractor that I think this may
: be the problem. I would like to know from those of you
: out there that have learned through the "school of
: hard knocks" just what the symptoms are. I don't want to
: take the head off unless I'm sure this is the problem. How
: can I know if it is the valves. I took a compression test and
: got 95 psi in all cylinders - does this mean my valves are good?
: Thanks for the help. DG