My 312 engine use a lot of oil every time the engine was running, I have changed the rear main bearing seal.

but a lot of oil was still running out when the engine is started, and the only leak I can see is in the area around the rear main seal?

Is this a special Y-block problem, or can there be an other reason to this oil leak problem?

You should have a look at the valley cover under the intake.Oil will leak from there and and run  down the back of the motor so it appears the rear main is leaking.Give the motor a good cleaning(steam clean cover the distributor and carb) and then you can see where its actually leaking from.Possibly the rear cam plug which is not visible until you remove the transmission may be leaking.Possibly the rear main seal is not properly installed.Go to Eatonbalancing.com and click on the Y-block info.Article on properly installing rear main seal.

  

There are also the oil galley and cam plugs which can leak. What does the oil smell like? Could be a transmission leak. Maybe the oil pump is loose.



The easiest way to find oil leaks is to get the engine as sparkling clean as possible. Then the trail is easy to follow.


Lawrenceville, GA