Quote:
Originally Posted by ecp
yup i have the head cover off, and removed the broken spring. was just trying to get my parts list together and wanted to make sure i didn’t need to add a bunch of things to it. Cyl one returned very little after doing the test again with more pressure put into it. I think it’s due to the fact that there’s a much smaller space for air to go since the piston is at tdc. starting at zero and firing up the compressor it builds pressure nearly as quickly as when an air tool is attached to the line.
there’s a slight hiss coming from back near the crankshaft area which i assume is just air seeping past the rings. it did it on all cylinders
after putting more pressure in and confirming air returned on cylinder one numerous times i think it’s worth a shot putting new springs in and trying to fire it up, and maybe it was just an ecu error causing cylinder one to not fire. I could be wrong, but i could be right. Only one way to find out.
The fact that the dealership only mentioned a valve being stuck open on one cylinder also leaves me to believe that they didn’t really find any other issues, but i’m gonna give them a call tomorrow and ask just to double check.
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At tdc, both intake and exhaust valves should be closed. Hence, whatever pressure you put in should stay there. Even in a small space, 25psi is a lot of air. If you aren't getting it back there is a problem. You are effectively doing a poor man's leak down test, but I don't think you're gonna get any kind of good diagnostic data with the way you're doing it. You said the dealership did a leak down - what did it show?
The bottom line here is that if a cylinder won't pressurize, or won't hold pressure, you have a serious problem.
One caveat there - we have low pressure piston rings. So, in the absence of a crank case vacuum, expect some leak down. Not complete loss though.
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