Dead cylinder

[Rod K.]

Re: Dead cylinder

But leak down test results were essentially equal across all cylinders, indicating no significant leakage, i.e., no bent valves, internal combustion config the same throughout. I would not pull the heads yet, think you're chasing something else.

[David M.]

Re: Dead cylinder

Try a wet and dry compression test. Is there a difference? The leak down is good. The dieseling and reverse rotation could have bent a push rod?

I had a similar problem 20 years ago on new 2.8 in an S15. Could not figure it out for quite a while. Compression was good, leak down was good, wet n dry test was good Cylinder balance test was good.

Rockers moved evenly(or appeared to). Scratched my head till it bled.

Root cause:
Amateur assembly. The PO ran the rocker nuts all the way down. Collapsed several lifters bent a few push rods and wiped a cam lobe(on the dead cylinder). It ran after backing the rockers off but had miss.

Solution:
New cam lifters, springs, P-rods.

[Anthony L.]

Re: Dead cylinder

Most definitely could be a bad cam lobe.

[Tom I.]

Re: Dead cylinder

Anthony, Engine has about 4000 miles on it since complete rebuild including new cam. Problem started after running engine about 10 minutes and three miles. Engine was running strong at shut down. I suspect engine ran backwards when shut down due to Pertronix misfire caused by loose magnet ring hanging down "speculation on my part. Pertronix was removed and switched to points and remains using points at this time.
Good compression on all cylinders 'tests run twice', Leak down test, all cylinders between 185 and 190 lbs. strongly suggest internal parts in good shape, except possibly bent valves and or bent push rods causing delayed or slow movement. running engine after problem includes valve noise getting worse with missing sound in both tail pipes.
This description is intended to be a general description of the problem.
Tom I.

[Anthony L.]

[Anthony L.]

Re: Dead cylinder

Just out of curiosity - are you still running last years fuel? Maybe have bad fuel recently? Might want to drain the tank and put good high test fuel in it .

bad fuel has caused many many people to chase problems they do t have. Especially at the beginning of driving season

[Tom I.]

Re: Dead cylinder

Anthony, the gas is fairly fresh some added shortly before the problem started. Car used mainly for weekly six mile cruise so fuel remains fairly fresh. Tom I.

[Anthony L.]