Water in Oil - Oil is milky.

[BriEOD]

Had this issue on my old boat twice. One time motor was f'ed (big thx to the previous owners--big pen)is!). The second time, it was the intake manifold. Enough metal had eroded around the water intake that water was dripping into the valley. Pull your intake manifold and take a look. Cost me $200 and a few hours to fix.

[thatsmrmastercraft]

Had the same problem when I first got my boat. Turns out it was the exhaust manifolds. Both had internal cracks that slowly allowed some water into the engine. It doesn't take much water to turn the oil into chocolate milk. I had the intake off several times looking for the source. I found water on the spark plugs when I pulled them after I had run the engine for a while. When I pulled the exhaust manifolds I found water droplets in the exhaust in the runners. Might be worth checking before you tear the engine down.

[Sodar]

I know that I am a total idiot and mechanically declined, but when I used to work at the offshore boat dealer, we had a case where the oil was looking milky, but it turned out that the oil pump was "aerating" the oil. My memory is very vague, as I was just the guy standing over the real mechanics shoulder getting him tools, but we were having issues with oil pressure, also.

Just thought that since the milkiness is returning and disappearing?

[BigJon]

What happens if one of the cylinders reads lower compression than all of the others. 7 supposedly read in the 165-170 range but the last was lower like 130?

[SkiDog]

Originally Posted by BigJon

What happens if one of the cylinders reads lower compression than all of the others. 7 supposedly read in the 165-170 range but the last was lower like 130?

Maybe a bad ring? Where the hell is JimN when you need him?

[nmcjr]

If one is lower like that, it sounds likely to be a head gasket. However, in my experience, head gaskets rarely blow for no reason--was it ever overheated?

As you disassemble the parts to get the heads off you will remove the other parts listed in the other posts above in order, so if you remove everything slowly and carefully, you can sometimes see signs of a leak on the parts or the gaskets--exhaust manifolds, intake manifold etc. so you may see the culprit before having to take the heads off. If you do take them off it may be worth it to magnaflux the heads as jim mentions, but I don't know how much $$ for this procedure.

The (somewhat) good news is that this is all work a shade tree mechanic can do, and will be much more time than money if it turns out to be just a gasket. You will need torque specs, good gaskets (factory GM or Indmar would be my recommendation) and a 3M gasket remover. It could fairly easily be done in a weekend, especially if you have a buddy who has done this before on a car etc. I would also suggest photographing everything as you go if you decide to take it on.

[thatsmrmastercraft]

Originally Posted by mneff1

About 6 weeks ago, I was changing my oil and I was amazed and scared about what drained out of my oil pan. The oil looked liked chocolate milk. So I took the boat to the shop and then filled it up with oil to check the pressure in the heads. Everything checked out fine.

So next they ran is at the shop for 30 minutes. No water. Then they took is out to the lake to run it hard for 30 minutes. Nothing.

So they told me to run it and keep an eye on the oil. Sure enough about 4 hours after the oil change and running and skiing behind the boat the milky oil started to return. So I ran it a couple more days because the oil level was not changing. So I looked again and the oil was back to normal, no milkness.

So I ran it a couple more hours and checked the oil. The milkness is back and it looks pretty bad now. The oil level is still unchanged. I took off the oil caps where you pour in the oil and I noticed it was milky up there and there were globs of it that looked like grease texture.

What do I do next? Any ideas of what to do or what could be wrong. I'm praying the block isn't cracked.

Thanks,

Mike

Hey Mike - are you a Minnesota guy? Might be able to lend a hand if you are in the neighborhood.

[mneff1]

Originally Posted by thatsmrmastercraft

Hey Mike - are you a Minnesota guy? Might be able to lend a hand if you are in the neighborhood.

Thanks. I'm actually a PA guy. I have a couple good guys in my boat club that are mechanics and I would like to try to do this with their help. I have never worked on an engine before but would love to learn.

Thanks to everyone who has posted. I hope from what I have read here the my block is not cracked and is probably one of the other things listed.

I will keep you all updated on my progress.

Mike