tmdog

Is it possible to perform a compression and leak down test on a cold engine with some degree of accuracy?

Dixie Doug

just did a comp & leak on 2 cold motors. all comp about 150lbs .on the leaks all cyls about 20% but #7 on both motors 60%star & 85% port. put oil in cyls same what's up?

KNOT-RIGHT

If squirting oil into chamber dosnt change readings. Im betting exhaust valve. Remove valve cover and rocker arm and tap valve stem with brass hammer see if leakdown changes. Usually you can hear the hiss in exhaust or intake.

Good luck
Gerry

vette131

probably carbon on the valves

Lmarth

All you guys are on top of this one! I'll repeat what I said in a post a number of months ago. A mechanics stethoscope really comes in handy to interpret leakdown findings. Ideally, with the exhaust unbolted from the head, valve covers off,etc. you can really hear what's happening. I'm afraid Dixie Doug may have some burned exhaust valves. You usually get a pretty good whoosh sound passed the rings which is normal. If you don't have debris screens in the lifter valley,you can get the stethoscope hose down by the cam to listen to the ring leakage. If you don't have blowers you can run the hose into the plenum area of the intake manifold to listen to the intakes.With the exhaust unbolted from the head, you can put the hose in the exhaust port. As you said, relative differences are what matters. Good Luck!

jpclear

Lou, "You de man", but you is givin away all de secrets. --- JP

Lmarth

Hey Clearman! Good to hear from ya. I thought you'd be in Florida. Best stethoscope I ever had, I 'borrowed' from one of the airlines many years ago (audio headset that I tore the end off).Latest 'crutch' is a stethoscope from Harbor Freight ($5.99). Also great for listening to bearings (front blower,water pump and alternator). After a few drinks, I'll really sing! Lou