Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks
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I am new to classic cars and using forums, so forgive me if this is a silly question.
I picked up a 1939 Chevrolet Master Deluxe that had been sitting in a barn for 65 years (the inspection sticker on the window is from 1957). I have been working on power equipment and small diesel tractors for 40 years.
The engine would not turn at all. Not surprising for how long it has been sitting. I pulled the engine and disassembled it. I had an elderly engine rebuilder rebuild it for me. I am now ready to reinstall the engine. When I picked up the engine to reinstall, I noticed a steady oil drip from the rear main seal area. Upon further inspection I noticed that there was no rear main crankshaft seal. At first, I thought the elderly gentleman that rebuilt the engine forgot it. Upon further investigation I am finding out that Chevrolet did not start using rear main seals until 1940.
So, my question is there a way seal this leak?
Bill,
Someone, who knows more about this than I do, will come along to help out. Here are some thoughts. When there is no rear main seal, there is an oil slinger built onto the crankshaft behind the rear main bearing. It spins in a cavity that has a drain, back to the oil pan.
If you picked the engine up and it was angled down at the rear, for lowering it into place in the car, oil would obviously run to the back of the pan where it could escape. When the engine is level and running, the system works, as designed.
A running engine that leaks at the rear main is a different situation. A clogged drain, from the slinger, can sometimes be the culprit.
I hope this helps.
Mike
Many Miles of Happy Motoring
3469 Posts on Old VCCA Chat
Remove the rear main bearing cap to ensure there is not a seal in the grove, or around the crankshaft. If there is a seal, remove it. The bearing cap should have one grove with a hole in the bottom that runs back to the crankshaft. There should be a check ball in the hole. Make sure the hole in not plugged and that the ball moves freely.
Hi Bill
Everything Mike and Mario have said is spot on.
The ball in the return passage from the slinger area was supposed to roll back and check the oil from FLOWING backwards through the passage into the slinger groove and straight out of the engine when the engine was tilted back.
As Mario said, the ball needs to be free and the ball and passage need to be clean.
All that said, the system wasn't a perfect seal.
With your engine hanging with a backward slope, I would consider a slow drip to be normal. A fast drip or stream would not be normal.
Ole S Olson
Saskatoon, Sask, Canada
1139 old site posts
Thank you all for the information. I will look into over the weekend.
also it would also depend on what angle the passage and ball were at in relation to the oil level and the lower edge of the rear edge of the slinger area when the leak will be evident
Tony
Dumb question here. Is the engine in the car? Is the valve cover on the engine? I remember doing valve adjusting and thinking oil was leaking from rear, but it was just running off from back of the head. After adjustments, replaced valve cover and gasket, leak was gone.
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