3th times replaced that issues. NEW seal, rear gasket, and rtv ......Even I replaced new oil pan gasket as well. Why it still leaking most is on rear main seal. I looked at crankshaft end of journal where seal lip was. It look smooth. Nothing cut or scratch on the journal crank.. Any idea will fix the problem, Im going replace new back plate, seal, gasket to see what happen.

 

Excessive crank case pressure can make the rear main seal leak too.

 

what crank case pressure is?

 

Based on your Signature you have a turbocharged truck. That turbo charger is what can cause more crank case pressure than normal because if that boost pressure is going past the piston rings it goes into the crankcase. If that pressure can't get out then it can start to push oil past seals.

This is just a guess as to what is happening.

 

Or backwards through the crankcase ventilation system.

 

Rear main has the largest surface area of any unrestrained gasket in the engine. It's the first to get pushed when the block can't vent sufficiently

 

You need a catch can. All forced induction engines do.

 

I’ll second that this is you solution.

 

Agree but I am the worst procrastinator in the world I guess. 55 K on mine since the Whipple and I never did but it's somewhere in storage so maybe next fall.

 

At least vent the valve covers