Rear main seal leak

[Litchkar]

I have a SB 340 with a leaky rear main. Can this be changed with engine in place without dropping the crank.

 

[Challenger RTA]

Rear Seal Leak
Freshly Rebuilt Engine Leaking

 

[pschlosser]

it's tricky. I've read about it being done. I've also read it can be done with the engine hoisted up a few inches, and dropping the crank some.

 

[Xcudame]

I can honestly say I have never built an engine without installing the upper rear main first. I like to install the main bearings and crankshaft, torque the main caps and check trust bearing clearance and check sometimes the oil clearance on one of the main bearings with plastigauge if I was too lazy to snap gauge and mic and calculate the clearance before hand. I dislike torquing engine parts and then taking them apart. So I always wind up rolling the upper seal half. The seal pushes in quite a ways easily and rotating the crankshaft sucks it into place. A dab of RTV on each end and with the lower attach to the rear main cap, bolt on, torque and done. Big blocks are even easier as they have the rear main seal housing that's separate from the rear main, so I never have to take off the rear main cap.