rear main oil leak

R

RJ

Member
my friend has a freshly rebuilt engine thats leaking oil badly out the rear main? the engine has inserts bearing installed does the rear main insert bearing come with oil return hole in cap?
 
RJ said:
my friend has a freshly rebuilt engine that’s leaking oil badly out the rear main? the engine has inserts bearing installed does the rear main insert bearing come with oil return hole in cap?
Click to expand...
I rebuild A & B engines with inserts. I have used conventional inserts and the new inserts designed specifically for A & B engines. In other words I am familiar with the process and have seen many adaptations of the process.
To answer your question: “does the rear main insert bearing come with oil return hole in cap?”
Typically a rear insert bearing will not have a hole that feeds directly to a hole in the cap. The oil that gets by the rear of an insert bearing is meant to be captured by the oil seal in the block and integral grooves in the cap, flow through the return oil passage in the cap and then down through the oil drop pipe. If the 5/16" or 3/8" pipe is missing or the oil passage galley plug is missing, there will be excessive leaking at the rear main in a freshly re-built engine. If the oil passage is severely restricted, there will be excessive leaking at the rear main.
I have seen rear main bearings modified with a drilled hole in the rear main cap from the bearing surface directly to the oil passage. This modification typically has a "trough" cut in the bearing surface of the rear cap to collect the oil. This is meant to collect oil and feed it directly to the oil passage rather than relying on the stock rear slinger and collection assembly or an updated cork or neoprene seal.

If the engine was assembled by your friend from a shortblock, have him check his assembly carefully as the leak would most likely be from his assembly work. If he took delivery of a long block, the leak would most likely be from work the engine assembler completed. Most engine builders will offer to help you trace the leak…they want you to be satisfied. Contact him as you see fit.
The rear side of the camshaft bore is prone to leaking if not sealed properly. This type of leak is hard to diagnose without removing the flywheel inspection cover and carefully studying the path of the oil.
A previous post suggested reading Rich's (Antique Engine Rebuilding) comments on oil leaks. He covers it quite well....check his link.
I am always willing to help troubleshoot the problem...PM me if you need additional help.
Let us know what you discover as to the cause of the leak.
Good Day!
Dave in MN
www.durableperforamance.net
 
RJ said:
my friend has a freshly rebuilt engine thats leaking oil badly out the rear main? the engine has inserts bearing installed does the rear main insert bearing come with oil return hole in cap?
Click to expand...

If I understand your question correctly, the answer is yes, the cap will have the oil return hole and should also have the tube that extends down into the oil.

How much oil did you friend put in the engine?
 
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