Oil leaking after changing to NV3550 trans

[tampabronco]

I've changed the rear main seal twice and still leaking oil. The seal and cap looked snug while I was in there. I noticed it leaking oil about the time I switched the trans. Is it possible an oil leak is related to a trans swap?

 

[DirtDonk]

I wouldn’t think so normally.
Unless somehow the bellhousing register hole was offset enough to create a bind between the transmission shaft snout and the back of the crankshaft. But rather than cause the rear main to leak, I would think that it would put excess wear on the transmission input bearing and seal instead
Are you sure it’s the engine oil that’s leaking?

 

[DirtDonk]

Was it a manual transmission before? If you replaced a flex plate with the fly wheel, did you use thread sealant on the flywheel bolts?
I can’t remember for sure, but don’t they go all the way through and can be a potential source of leaks?

 

[73azbronco]

Thread sealant.

Was it leaking before swap? Might be bad surface on crank.

 

[tampabronco]

Was it a manual transmission before? If you replaced a flex plate with the fly wheel, did you use thread sealant on the flywheel bolts?
I can’t remember for sure, but don’t they go all the way through and can be a potential source of leaks?

It was a stock 3 speed before the swap. Not sure if I thread sealant