Join Date: Mar 2012
Car: '15 FXT
Feedback Score: 0 reviews
Zero compression usually means one of a few things namely:
If when performing a leak down test the compression rises significantly it is a piston issue. If it stays the same it is a valve issue. I don't know your engine specs but 5-10% difference can be normal, more than that is bad.
If you have oil coming out the tailpipe, you likely did the leak down test incorrectly or your engine is toast. Rotten eggs is a tell tale smell of a blown engine btw. You only need a small amount of oil to perform the test. If you are confident you did the test correctly you may have a broken crankshaft. It is really rare to have zero compression in more than one cylinder on both sides of the engine and have it be a piston issue. What you are describing sounds like the valves are not sealing correctly.
Of Course if you have a broken crank, nothing would line up right and the valves would be open when you do the tests. Lets hope it's something simple. It sounds bad at the moment. If a pulley went bad or the chain/belt was loose or broken you might experience what you are describing.
If it were me:
Perform a compression test on all cylinders. If all cylinders are zero it is likely a valve or crank issue.
A) Compression is zero on all cylinders, most likely a valve issue: a) double verify timing belt is correct b) Verify that the crank is in the proper alignment which is more difficult.
B) Compression is good on other cylinders but not the two: Suspect bent valves on bad cylinders
From here we could check more but I'd need to know the results of that to proceed.
My first guess without seeing it is the chain/belt/pulley broke.
Edit: Also make sure you are using the correct threads for your compression tester. Line them up with the spark plugs to be sure.
Common sense, isn't common.
Current: '15 FXT
past '12 2.5L OB
Last edited by Novablue; 11-07-2012 at 09:52 AM.
Reason: Gotta cover the "DUH!" stuff too.