Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks
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Hey all not new to restoring old cars, but new to VCCA! I have a mostly original ‘39 Master 85 and finally had a shop go through the engine. I was shocked when I visited during the rebuild to find there was no rear main seal! Everything I had looked up trying to diagnose my leaking engine discussed the rope seal vs newer rubber wiper retrofits - so I was expecting to have to make that choice, but it literally doesn’t have one…
The engine shop noticed a very slow leak after getting it back together and tuned. The lead mechanic said these old motors w/o the rear main seal were very particular about the bearing clearances. He ended up taking some out of the bearing shim set and the thing sealed right up. I’ll have to ask what the final main bearing clearances were to get the leak to stop. Still shocked there is no rear main seal in these pre-1940 stovebolts.
@39master85 On the old Chat site you may find more information including adding a groove to the rear bearing to allow the oil to more easily return to the pan. The older chevys are known for "marking" their spot and in fact some owners claim that if it does not leak it is because it is out of oil!!.
7472 old site post
@39master85 Welcome to the VCCA Deric. This should be a stand alone thread rather than a piggyback. I'll give it a day or so for you to see this reply then I'll split your post off into it's own thread.
7046 old site posts
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1938 Master Business Coupe
1953 210 Sedan
@tiny - appreciate the welcome and I have seen the reply. I pick the car up next Monday so excited to see the motor back in it.
Any rear main bearing gap over 0.002" is likely to drip or seep a little oil. Just enough to be a visual problem but not even close to excessive oil use. If over 0.003" it will leave a spot whenever parked. The bigger the spot the more over that gap. Of course that assumes that the passage back to the oil pan is clear flowing. Like many older folks a "Depends" either onboard or on the ground can help.
How sweet the roar of a Chevy four
Participant on Chatter since 11/22/2001
19758 posts on the former Chatter site
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