Maybe Dave has an idea, engine was running fine, all of a sudden I feel a heavy miss after hearing lifter-like tapping noise. Pulled plugs and compression is zero in cyl # 4. What could have caused valves to stick open? Cyls 1,2,3 are fine at 170psig. Timing belt is fine in synch. ???
88 rocco:No compression cyl#4!??
Dec 04, 2007
6 Replies
16V or 8V engine?
Do the spark plugs still look fine?
Might want to do a Leak Down Test to find out where the compression is going to. Also might want to pull the valve cover to peak at the lifters/followers and camshaft(s).
Not sure here! Maybe Dave has an idea, engine was running fine, all of a sudden I feel
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Hey thanks a lot guys, I'll go along with Chuck's idea, it makes complete sense. I saw a 16v 944 got a broken spring and it had a variable miss, lucky thing the inner valve apring kept it all together and valves never got mashed, just replaced the spring and that was OK
Update: Finally decided to pull that head out, and I gotta say CHUCK YOU"RE RIGHT!!! upon removing the valve cover, i pushed on the 2 exhaust lifters and found the rear one went down under slight pressure. Took the head down and yes sir bent valve enough to see light thru the seat. Orser my parts and she will be fine again. THANKS CHUCK!!
So hopefully the top of the piston is ok, and no other damage occurred. If you haven't done so, check it out before you order parts.
Checked it right away, piston crown fine, parts ordered, first batch came in today, great stuff. Valve's slightly bent. I'm removing the headers and collector and going back to stock exhaust manifold and downpipe, already bought on ebay. Headers anyone?
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