rear main seal leaking

[marvinjansen]

My 1973 Mercruiser 165hp inline 6 is leaking at the rear main. Leaks about a quart for a tank of gas (16 gal). The engine was put in in 1988 and has low hours but sat for 8 years. Any chemical solutions that work? Runs great and will continue to use till fixed, just don't drain the bilge at the landing.

 

[picklenjim]

Re: rear main seal leaking

That's a LOT of oil to be leaking per 16 gallons of fuel. It's very possible that it's something other than the crank seal. There's no stop leak in the world that would stop a leak that big. That should be addressed immediately before you accidentally smoke the motor.

 

[marvinjansen]

Re: rear main seal leaking

What else on the back of the engine could leak? replaced valve cover gasket and it is now dry at the back of the head. wet at bottom of bottom of bell housing and front metal cover. Just replaced head freeze plugs with brass ones after one rusted through. Any cam plugs in the rear that might have rusted out?

 

[Bifflefan]

Re: rear main seal leaking

Everytime you hit the gas the oil slops to the rear of the pan leaks out.
There is a few things that soften the seals but the amount of leak you have needs to fixed correctly. It doesnt take but about a day (or less) to do it if you have the tools and lay off the beer until your done.
The only other thing is the cam plug. Either way your pulling the engine.

 

[Bondo]

Re: rear main seal leaking

Any cam plugs in the rear that might have rusted out?

Ayuh,... One...

 

[picklenjim]

Re: rear main seal leaking

Could be the pan gasket which would be more likely than the main seal to be leaking that much.

 

[marvinjansen]

Re: rear main seal leaking

Bet you're right. Will have to pull engine or have it done.

 

[Fishermark]

Re: rear main seal leaking

The oil pan itself could have even rusted. Really the only solution is to pull the engine and get it fixed - whatever it may be.

 

[marvinjansen]

Re: rear main seal leaking

Tightened pan bolts, only a little in the back. also put in Bar Leak Rear Main Sealer and it may be helping. more time will tell.

 

[mkast]

Re: rear main seal leaking

Core plugs.

 

[marvinjansen]

Re: rear main seal leaking

what are core plugs and where are they?

 

[mkast]

Re: rear main seal leaking

freeze plugs

This is called a core plug.

 

[marvinjansen]

Re: rear main seal leaking

I had wondered if the plugs at the back of the motor, like for the cam, might rust out and leak. It isn't leaking water from there as far as I know.

 

[mkast]

Re: rear main seal leaking

after one rusted through

And the rest?

 

[marvinjansen]

Re: rear main seal leaking

The one on the side of the block are brass, and the ones in the head are now brass after I replaced the rusted out steel ones. I don't know about ones at the rear of the engine.
there may be freeze plugs and a cam bearing plug, not sure. Would think a plug in an area exposed to oil would not rust.

 

[marvinjansen]

Re: rear main seal leaking

Last outing Monday didn't leak. May be tightening bolts a fraction or the Bars Leak for Main seals. One less problem for now.

 

[Don S]

Re: rear main seal leaking

Ahhhhhh yes, Mechanic in a can. Temporary fix at best. Wonder what else it plugs up while "Fixing" your leak.