89Camaro89MI

iTrader: (2)

I've got an 89 RS with the 305. There's an oil leakage problem which I've narrowed down to being the Rear Main Seal.

The Haines manual is only so helpful, so before I break down and take it to my local mechanic, anyone have any advice?

I understand replacing it (it costs about 20 bucks) requires either the complete removal of the engine, or the removal of the transmission from the engine, while the car is lifted.

RFmaster

Blown rear main seal on post 87 SBC is somewhat rare occurrence. It is a single piece design, which is by far better than original two piece first gen SBC design used from 55 until 86!
Yes, the only way to replace it would require removal engine from engine bay. You have to remove oil pan - which is difficult with engine sitting in the engine bay (cross member). Removing transmission allows access to the rear of the engine, but pan needs to be dropped to gain access to the rear main.

Are you absolutely sure that it is rear main seal??? It is very common for the China wall to leak in the back of the engine.

//RF

five7kid

iTrader: (14)

The oil pan does not have to be dropped to get to the rear main seal. If the rear main seal carrier gasket is leaking, then you have to drop the pan.

Agree that a one-piece RMS leak is pretty rare - that's why they went to the design. More common is intake gasket, valve cover gasket, or oil pressure sender, any of which will drip down to the bellhousing area.

How did you determine the rear main seal is leaking?

89Camaro89MI

iTrader: (2)

Honestly, that's my father's Diagnosis. He used to drag race semi-professionally, so I just kinda took his word for it.

I havent noticed too much level decrease in the engine. Just a few black spots on my driveway.

I checked the intake and valve cover gaskets - they're fine (old, but okay). Oil pressure sender... I'll have to go look tomorrow. It isnt really originating at the bell housing. The leak comes from a cover plate between the oil pan and transmission, I think, and collects on the surface of the oil filter, and drips from there (it isnt the oil filter - I checked).

I'm worried that the jerkoff previous owner was shabby with his oil upkeep and the crankshaft and surrounding components are damaged from oil starvation. Wear from Crankshaft vibration would explain why my main is leaking.

Pocket

iTrader: (24)

More than likely its the pan gasket which is a bear to do in the car

Get some degreaser and clean everything and watch for fresh oil. Youll find your leak and not have to worry about guesswork