How to tell if shortblock is ok?
How to tell if shortblock is ok? I took my heads off my car after a leakdown test revealed some pretty nasty numbers. My best number was 38%...my worst was 85%. I had air leaking past the intake and exhaust valves big time (and the damn thing ran pretty well until it started overheating). My question is, how might I determine the health of the bottom end w/out removing it from the car and dissassembling it? If there is a good way to tell if it's hurt or not...I'd like to avoid pulling it. I'm thinking about squirting a few ounces of oil in the cylinders and seeing if it leaks past the rings overnight. I'd imagine it won't go anywhere if the rings are still fine. BTW, the bores all look real nice...with no apparent scratches or damage that I can see. Is it possible for a ring to be cracked and not cause any noticable damage to the cylinder walls? My next step is to drop the heads off somewhere and have them pressure tested to see where and why they're leaking.
Thanks for any comments or suggestions.
Thanks for any comments or suggestions.
You should have been able to determine the health of the shortblock during the leakdown test. Did you listen for air hissing out through the oil filler neck? A bunch of air coming through there during the leakdown test would indicate a worn bottom end. Did you check all of the places that air can escape through during the leakdown test? Back through the TB, exhaust pipe, oil filler neck, and head gasket area?
Hand crank the motor over and check the crosshatch pattern in each cylinder, thats about all you can really do at this point without pulling the motor. Major scoring of the cylinder walls can be an indicator of wearout.
Hand crank the motor over and check the crosshatch pattern in each cylinder, thats about all you can really do at this point without pulling the motor. Major scoring of the cylinder walls can be an indicator of wearout.
leakdown I listened in all the above mentioned places and heard it big time through the throttle body and through the exhaust. I had the valve covers off when I did the leakdown and didn't notice it so much there. The cylinder bores look brand new. I contacted Doug Rippie of DRM and he said a simple test to see if the valves, guides and or seats are leaking is to remove the heads and place them combustion chamber up...then pour solvent into the combustion chamber and introduce high pressure air through the intake and exhaust ports. Doug said "If you notice the solvent bubbling around the valve...your heads are junk". I told him I had the welded Patriot 5.3 LS6 style heads and he said he had a customer in his shop recently and had big trouble with the same 5.3 welded heads. He says that Patriot doesn't heat treat the heads after welding them and the material is too soft to keep the valve guides and seats from "walking around". This introduces oil into the intake and exhaust ports causing all kinds of trouble. This fits perfectly with the situation I currently have. Looks like a pair of real LS6 heads or some AFR's. 
