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D16Y7 engine 160,000 miles. So this is actually my sisters car and got a call saying her car wouldn't start. As soon as I heard the car turn over I instantly felt it was a timing belt because of the way it cranked sounding like a compression problem. I was surprised to see with my scope using a relative compression and ignition probe synced with cylinder 1 that it appeared to be spot on however I could see (and obviously hear) it had compression issues on the waveform. I did a compression test and verified that yes I have very low compression in ALL cylinders. I started to doubt myself on the relative compression a little so took timing cover off and verified the timing is spot on. I then did a cylinder leak down on each cylinder and found that every cylinder is bleeding compression into all the other cylinders. I have 65-80% loss on all the cylinders. BUT.... I'm getting very little to none escaping from the exhaust or intake valves... No loss to the crankcase except a very small amount on cylinder 2. No loss at all thru the radiator. No mixing of any coolant and oil.... Just loss between the cylinders on EVERY cylinder. I verified with my sister that the car has NEVER been overheated. She said she usually drove it everyday but this time the car sat for 4 days. She said she started the car up like normal... it ran for about 30 seconds and then started to sputter and died... and when she went to restart it... it sounded funny when she was cranking it and it would not restart. My question is... has anyone seen a head gasket fail between all the cylinders at ONE TIME like that? And then not have any loss to the coolant or oil passages? I guess I am just really having doubts about this diagnosis because it just doesn't seem plausible to me... am I missing something maybe? Need opinions. Thanks guys
Did you do the leakdown with the throttle propped open? An exhaust restriction could also affect the results. I'd maybe pull the upstream O2 and test again.
Beyond that I tend to question the owners story in situations like this. Does anyone else have access to the vehicle? Kids/grandkids and boyfriends are the prime suspects in cases like this.
My brother in law has access to the car but no kids because its a 5 speed haha. I can't completely eliminate the possibility of an overheat if my bro-in-law drove it, which he said he had not, but I do trust my sister that it didn't overheat with her. I didn't have the throttle plate propped open during the test but I opened it while testing every cylinder while listening for any air loss to the intake at the throttle body and there was no abnormal loss so no, I never pulled the O2. My sister said the car ran great before and this was an instantaneous thing after start up so never really went down that road. The bleeding between all the cylinders is where my focus has been. If I am at top dead center doing a leak down... would a plugged exhaust affect that? I shouldn't have more than 20% loss regardless unless I had an exhaust valve problem too right?
Lowboybrian wrote: My brother in law has access to the car but no kids because its a 5 speed haha.
So it's equipped with M.A.T.S. :lol:
Lowboybrian wrote: If I am at top dead center doing a leak down... would a plugged exhaust affect that? I shouldn't have more than 20% loss regardless unless I had an exhaust valve problem too right?
Valve problems are why I mentioned both the throttle and the possibility of an exhaust restriction. If the air is leaking past the valves it'll go to another cylinder if that's the easiest path.
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