QuestionQUESTION: I have a 1990 Chevy Astro Van with a 4.1 l motor. I parked the van in January of 2008. After three weeks of Michigan winter I tried to start the van but it would only backfire through the intake and exhaust. I assumed a timing problem. Once summer came I checked the timing chain. It was tight enough and had not jumped a tooth. I have adjusted the timing to no avail. I let the van set for awhile, when I returned to work on it wouldn't turn over. It would not turn by hand with a wrench on the crank shaft bolt. We broke it loose by removing the spark plugs and pouring a little WD40 in the cylinders. It is now turning over freely but will not start or try to start it just backfires. I need your help. I don't know what to check next. Thank you
ANSWER: Start by checking compression. minimum compression should not be less than 100 psi
let me know what you get and we can go from there.
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QUESTION: It took me a while but finally got cmpression test on 1 through 5. I couldn't get to #6. the compresion is as follows: 1=85 psi, 2=134psi, 3=135 psi, 4=160 psi, 5=120 psi, 6=?. Whats next? Thank you.
Answeryou have some serious issues there. #1 compression is not high eneough to support
combustion , in other words you are a 5 cylinder assumeing that #6 is ok.
if you want to try to fix this expect to spend a lot of money.
this is either rings or a valve problem both are pricey to fix.
without a leak down tester , finding out wich it is , is almost impossible
