1991 4.3 OMC Oil and Water

[bytwnracer]

Engine was working great just smoking so I turned off engine and looked at engine compartment and found oil and water sludge coming from carb. What could possibly be the issue? I bought a leak down tester and waiting for it to arrive but I'm thinking possible head gasket? Oil was new but now it's full of water and oil. Boat and engine have 211 hours and it is the orginal to boat.

 

[itsathepete]

Could be head gasket, intake manifold gasket, cracked block etc. First time out this year? Overheated? Improper winterization? If you think the motor can be saved you need to drain/flush all the milkshake out ASAP! I would drain what I can and fill the block all the way up with diesel fuel and drain it. Possibly do it twice.

 

[Bondo]

Ayuh,..... With no backstory, my guess is a freeze busted block,.....

 

[bytwnracer]

Could be head gasket, intake manifold gasket, cracked block etc. First time out this year? Overheated? Improper winterization? If you think the motor can be saved you need to drain/flush all the milkshake out ASAP! I would drain what I can and fill the block all the way up with diesel fuel and drain it. Possibly do it twice.

Yes first time out this year. No it did not overheat. It was winterized but I'm located in Houston area. Engine should be salvageable I think.

 

[Lou C]

Sad to see that with such few hrs. I have the same engine in my boat. Mine blew both HGs about 6 years ago but it was likely due to an overheat 3 years before that. I got the water out of the oil fast (salt water) and was able to save it. Installed reman heads because the originals were cracked.
When you winterized it, did you probe the block drains with a pick to make sure they drained? Or did you use the suck AF up the drive method?
You should run it enough to heat it up so you can change the oil 2-3 times then drain all the water out, and test the cooling passages with air pressure.

 

[itsathepete]

You should run it enough to heat it up so you can change the oil 2-3 times then drain all the water out, and test the cooling passages with air pressure.

@Lou C Are you suggesting removing the impeller and running without water? Wouldn't running with water flowing just milkshake again?

 

[Scott Danforth]

Ayuh,..... With no backstory, my guess is a freeze busted block,.....

my suspicion as well

Yes first time out this year. No it did not overheat. It was winterized but I'm located in Houston area. Engine should be salvageable I think.

confirmed. winterization failure for two reasons

first, its in Houston and that whole area of texas went thru a hard freeze last year
second, first run of the year.

@bytwnracer .... seriously doubt the block, heads, and exhaust manifolds are salvageable. specifically how did you winterize. if you say you sucked up antifreeze without draining everything, you did not winterize

time to drain the water jacket and pressure test. you may get lucky and only have a busted intake.

 

[bytwnracer]

my suspicion as well


confirmed. winterization failure for two reasons

first, its in Houston and that whole area of texas went thru a hard freeze last year
second, first run of the year.

@bytwnracer .... seriously doubt the block, heads, and exhaust manifolds are salvageable. specifically how did you winterize. if you say you sucked up antifreeze without draining everything, you did not winterize

time to drain the water jacket and pressure test. you may get lucky and only have a busted intake.

I'm very confused right now as the "oil and water" mix that I drained from engine in not acting like oil and water. It's very thick with a honey like consistency. I have let the oil sit for 24 hours and there has been no separation of oil and water. I did mix in a cup the oil from engine and added a little water and it separates like it should, but what came out of engine is not.

Now to engine I twice flushed it with diesel and drained. Changed oil and filter and ran to temp and changed oil and filter again. I did a leak down test came back good and compression test also came back good. Changed to new spark plugs. I ran boat on water hose and no signs of water in oil. I'm at a lose on what's going on. Any ideas?

 

[Lou C]

Sometimes when running it on the water hose the engine doesn’t get hot enough to cause leaks in the cooling system to bleed over into the oil. The only true test is a run under load in the water.
Air pressure test the cooling passages first. When my HGs blew I could run it on the water hose with no water….at first…but after the engine cooled….sure enough water would appear in cyls #2 and just a little in #1. Like the next day I’d see a bit of water again.
It took a while to see any evidence of water in the oil running it on the water hose due to no load on the engine.

 

[itsathepete]

I'm very confused right now as the "oil and water" mix that I drained from engine in not acting like oil and water. It's very thick with a honey like consistency. I have let the oil sit for 24 hours and there has been no separation of oil and water. I did mix in a cup the oil from engine and added a little water and it separates like it should, but what came out of engine is not.

You have an emulsion. Same concept as mayonnaise. It might separate out after a long time or it may never separate.

Sometimes when running it on the water hose the engine doesn’t get hot enough to cause leaks in the cooling system to bleed over into the oil. The only true test is a run under load in the water.

This

 

[bytwnracer]

Assuming the block is not cracked, is it worth the effort to save it since it got water in it or should I scrape it?

 

[Lou C]

Well yes but you won’t know unless you do an air pressure test of the cooling system. How did you winterize it? Suck AF up the drive? That’s no good unless you drained the block first.
That much water had to come from somewhere!

 

[Scott Danforth]

I did a leak down test came back good and compression test also came back good. Changed to new spark plugs. I ran boat on water hose and no signs of water in oil. I'm at a lose on what's going on. Any ideas?

define good

what are the numbers for the compression test
what is the percentage of leakage for the leakdown test?

how did you winterize?