1980 3.0 140 Rear Main Seal

[Alumarine]

I've got a question for the motor pro's

I'm replacing my transom so I have my 1980 3.0 140 on a stand.
I took the oil pan off to remove some rust and paint it.

Should I replace the rear main seal at this time? Or leave well enough alone.
According to a tag on the motor it was rebuilt in 1993 and it runs perfect.
The seal is not leaking. It's a 2 piece seal I believe.

Thanks for any advice

 

[fishrdan]

20+ year old seal, I would replace it, especially since 95% of the job is already done. I'm pretty sure that's a common seal and shouldn't be hard to come by at the local auto parts store.

Might be a good idea to reseal the entire engine while you have it on the stand. There is a 1-peice oil pan gasket for that engine which makes sealing the pan easier. I have used both the 1-piece and 4-peice and haven't had problems with either, but the 1-piece is more fool-proof, also more expensive... Most of those gaskets are automotive, but you'll need some that are specific to marine also.

If doing an entire engine reseal, I'd buy an automotive engine gasket set and a marine manifold gasket set (both FelPro) and make the few gaskets not included by hand.

 

[Alumarine]

I have a 4 piece oil pan gasket on hand and have been trying to find a Felpro 17951 1 piece set if that's the right number.
Do you use RTV with the oil pan gasket?

If I replace the rear main seal I think I'll use a Felpro BS40013 seal.

I think that's all I would do at this time though. All the other gaskets including the front seal can be replaced in the boat.

Thanks for the ideas.

 

[fishrdan]

I use a small dab of RTV where the rubber and cork gaskets meet with the 4-piece set, Permatex Aviation sealant on the cork and then the rubber end gaskets go on dry. With the 1-piece gasket, just a small dab of RTV at the corner where the rear main cap meets the block and at the front timing cover, then the gasket goes on dry. Don't use RTV on the surface of the 1-piece gasket or it will slip.

Since you have the 4-piece set on hand, I would use it. The 1-piece gasket is expensive, and since you already have the 4 piece set, might as well use it.

 

[Alumarine]

I use a small dab of RTV where the rubber and cork gaskets meet with the 4-piece set, Permatex Aviation sealant on the cork and then the rubber end gaskets go on dry. With the 1-piece gasket, just a small dab of RTV at the corner where the rear main cap meets the block and at the front timing cover, then the gasket goes on dry. Don't use RTV on the surface of the 1-piece gasket or it will slip.

Since you have the 4-piece set on hand, I would use it. The 1-piece gasket is expensive, and since you already have the 4 piece set, might as well use it.

Thanks for the install info.
I can't seem to get the one piece anyway. Napa doesn't have it in Canada and my other 2 suppliers don't even list it.

 

[Alumarine]

Update. Went with a Fel-pro BS11829-1 offset seal.
There was a very slight wear mark from the old seal so I went with the offset.
Here's a picture showing the standard seal by the offset seal (in blue) if anyone's interested.