Merc 3.0 breather question

RickM39

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Joined
Oct 12, 2008
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2
I recently bought a 1990 Sea Ray 180 with a 3.0 Mercruiser Alpha gen 1.

I've put 28 hours on it so far, and solved several problems with the information I've found on this forum.

One nagging problem is oil leaking down the aft side of the carburator onto the manifold from the crankcase vent line. In 28 running hours the oil level on the dipstick has not moved and the engine runs great.

In every motor I've worked on over the last 40 years that has an atmospheric crankcase vent there was some kind of filter media, like a coarse sponge, that would allow the liquid oil from the vent fumes to collect and run back into the engine.

Under the valve cover are two webs forming a channel under the nipple for the vent, but the channel is empty.

I've looked at the online parts books for the motor and they list the valve cover but no info on any baffle for the vent.

Is there supposed to be something in the channel?

The S/N of the motor is OC658131. Thanks in advance for your help.
 

chiefalen

Captain
Joined
May 18, 2008
Messages
3,598
Re: Merc 3.0 breather question

There is supposed to be a baffle under the valve cover.

Are you over filling the crankcase with oil?

Hard to tell with boats cause the boat is rarely level, or the motor i should say.

I don't go to the top of the full line but in between the add and full.

I think it calls for 5 quarts with filter change.
 

RickM39

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Oct 12, 2008
Messages
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Re: Merc 3.0 breather question

Thanks for the quick replies, the previous owner changed the oil last and it's just below full.

Back when I had a Cessna 170 I never filled the crankcase all the way, as the first quart would be lost pretty quick.

The valve cover is cast aluminum and the channel is cast into the valve cover.

Every other engine I can remember had some kind of an element in the breather, sometimes called a "moss" or like very coarse steel wool.
 

chiefalen

Captain
Joined
May 18, 2008
Messages
3,598
Re: Merc 3.0 breather question

No nothing like that, a square metal piece under the hole.
 
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