3.0l - Lost power, milky oil, good compression

[lr3guyjoe]

I picked up 2001 searay 180 today as a project for my son and I over his winter break. I putts around with small Johnson outboards I’ve never fooled with a mercruiser. From what I have read here if maintained the 3.0 is a good motor. So I’m hoping the issue is nothing major.

The story I got from the original owner was they took it out for a ride in about and about 15 minutes into the ride we start losing power. They were able to slow motor back to the trailer. The guy saw milky oil on the dipstick and parked it.

It’s a Central Florida boat so it mainly saw freshwater and brackish water. I’m hoping it is not a freeze issue being we hardly ever get a hard freeze here.

Ive checked the compression and it’s in the 150s across the board. Doing my initial checks I found the drain line for the exhaust appear to be off. I’m not sure if this could be a cause or if the previous owner disconnected it from there instead of up at the top?

Any suggestions on where I should start looking first?

Thanks in advance for any advice.

 

[Scott Danforth]

could be any number of things

could be an over-heat
could be rusted manifolds
could even be freeze damaged (yes, last year got below freezing even in central Florida)

 

[alldodge]

Pressure test the cooling system between 15 to 20 psi

 

[tpenfield]

I'd do the tests suggested. Also a cylinder leak test.

Water in the oil would possibly be head gasket of exhaust manifold gasket, as mentioned.

How long is the son's winter break :noidea: . . . might need the spring break too

 

[lr3guyjoe]

Okay did I pressure test of engine and head cooling system. Held a little over 15psi for 15min with no drop.

After that I did an oil change and got started it up to verify it does run. It did but like garbage. I got it fired up dry first for a few seconds then with the cooling system primed and full it I tried starting it and seemed like it was sucking water in and expelling. Like water got launched out exhaust in a rapid pulse.

Tore the head off and head gasket and gasket looked good. Manifold gasket looks a little iffy but it didn’t really come off in one piece. The exhaust valves on cylinder three and four or eight tan color, the rest are all black carbon color.

So if I’m lucky maybe just a cracked manifold? Would that much water get pushed by the rings to get the oil milky?

Im going to pour some acetone in the water inlet of the manifold and see if it were out the intake runner.


Failed to do a leak down test before I tore the head off.

 

[alldodge]

So if I’m lucky maybe just a cracked manifold? Would that much water get pushed by the rings to get the oil milky?

It doesn't take a much water to show up milky. The head gasket looks good, so I would suspect the manifold

 

[lr3guyjoe]

It’s 1&2 not 3&4

 

[lr3guyjoe]

Can these manifolds be magnafluxed?

 

[alldodge]

Can these manifolds be magnafluxed?

From the looks of the head, then ports are rusted up even on the gasket intake/exhaust surfaces. With that I would say your manifold is shot, it has been leaking for some time.

Take the head to a machine shop to get their opinion if it can be saved