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Discussion Starter #1
Recently installed a new 363 crate motor. Have ran the motor for about 5 heat cycles. Have an oil leak at the back of the engine, that only appears when the engine is running.

Oil is dripping from the front of the bell housing, as well as drips coming off of the transmission case.

I’ve double checked the back of the intake, as well as back of valve covers, and don’t see any trace of oil there.

With this being a newly built crate motor, the only two places the oil can logically be coming from: the flywheel bolts or excessive crank case pressure pushing oil past the rear seal.

I’ve traced back a few of my install steps. Flywheel bolts were installed to torque specs, and I included loctite.

I have a pcv valve installed on the passenger side valve cover. Hose running to vacuum port at the base of the Pro-Flo 4 throttle body. Breather is installed on the driver side, with hose connected to the air cleaner base.

Looking for help and/or opinions on this issue. Are there any other items I can look into to determine the cause?
 

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Just some guy
67 coupe, 69 Sportsroof, 86 hatchback
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First thing I'd do is WIPE along the back of the intake and valve covers. Brand new oil leaking back there on a clean engine is invisible. Too easy to do before things get more complicated.
 

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Discussion Starter #3
First thing I'd do is WIPE along the back of the intake and valve covers. Brand new oil leaking back there on a clean engine is invisible. Too easy to do before things get more complicated.
Have wiped behind both valve covers and at the back of the engine between the bell housing and intake. Not a trace of oil that I can pick up on blue shop paper towels. I had wiped the area after the initial startup when oil was noticed, and also just today. There’s nothing there that I can find.
 

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It's a thing. At least for me. I've had my 331 in and out of the car over a half dozen times and replaced the rear main seal most of those times. It generally just leaves a hanger of oil that eventually results in a drop of oil on the floor if the car sits for a week. It's a cheap commie crankshaft.What did you expect?
 

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Sounds like the rear main seal is leaking. I had my 331 leak right after installing the new engine. Installed a teflon seal and has not leaked a drop in 12,000 miles.
 

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Discussion Starter #6 (Edited)
It's a thing. At least for me. I've had my 331 in and out of the car over a half dozen times and replaced the rear main seal most of those times. It generally just leaves a hanger of oil that eventually results in a drop of oil on the floor if the car sits for a week. It's a cheap commie crankshaft.What did you expect?
I wish it was only a drop. Mine ends up dropping enough in a couple of locations depending on where it runs down. Drips from front of bellhousing back to the tranny. The picture attached shows where I end up five minutes after shutting down. Also added a pic of the car just for fun.
753024

753026
 

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I wish it was only a drop. Mine ends up dropping enough in a couple of locations depending on where it runs down. Drips from front of bellhousing back to the tranny. The picture attached shows where I end up five minutes after shutting down.
View attachment 753024
That is a bit much. Our Coronavirus friends aren't known for precision. I'm at $10G trying make a $225 commie crankshaft work. I suggest puppy training pads instead of cardboard.
 

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The two large bolts on the rear of the pan can leak after running the engine, and stop leaking when not running.
They don't go into blind holes, and need thread sealant.
 

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I’ve always heard that rear main seals can be troublesome on SBFs and it’s pretty easy to mess up the install of the seal.

I’m currently successfully ignoring a smal rear main seal on my 5.0 that has 11 years and probably less than 10k miles on it.
 

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My money's on the oil pan gasket where it runs over the #5 cap at the back.
 

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Discussion Starter #12
My money's on the oil pan gasket where it runs over the #5 cap at the back.
Are you saying that RTV should be used for that entire area, or just at the oil pan corners? Would that location cause a leak while sitting, or only while running?

Thanks for your help in advance.
 
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