Comment on the thread on compression tests on old engines...
I recently acquired a '39 Chev pickup with a 235 under the hood. Best I
could tell, it hadn't run in 18 years.
It was quite clean under the valve cover and the previous owner stated that
it had been rebuilt not long before it was "parked". Consequently, I didn't
want to tear into it if I didn't have to. I went through the fuel system
and the ignition system and pulled the plugs and turned it over by hand. I
could feel and hear the rings scraping on a film of rust in the cylinders so
I shot oil through the plug holes to help out. This procedure got it
turning smoothly so I cranked it with the starter while I checked
compression. I was displeased to get results form 50 to 90 psi.
Well, I got it started. It ran a little rough at first but improved. I ran
it several times and just last weekend checked compression again. Would you
believe, 120 psi in each cylinder? Yes, I figured the valve seats and
cylinder walls had a film of rust that prevented full pressure. This was
worn off when the engine was run.
Moral of the story: Don't give up on an old engine!!
Whitney Haist
1 '39, 2 '46s
CA
oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
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