water in oil

[csl]

Hey, got some questions on how this water system works. First I will explain whats happening. Boat was running great all day last weekend. Shut it down after boarding and it wouldn't roll over at all when we tried to start back up. Checked water temp and oil. It all checked out great. Had another boat jump us and we started up after struggling for a while. Ran right to the marina and loaded up. When we got home the oil is very milky.
Here is what we have done. Started with a compression test. We can't get the motor to roll over as freely as it should, so something is hindering that. The compression was weaker than would like, but if we get things rolling over better it may go up. Compression was consistent at 95-100. We drained the water and unhooked the hoses from the exhaust manifolds and sealed them up. Then added air pressure to the water system. It is going down slowly, but not much. so I don't think we have a large leak somewhere. with consistent compression, that seems to rule out head gasket and such. Right??? Father in law is my mechanic on all this and he is curious on the exhaust manifolds, what keeps the water from going back down the exhaust since the pistons are not a perfect tight seal?
I know this is long winded but we basically have a starting issue, charging issue or something along with water in the oil and can't find an obvious reason for the water in oil. any feedback would be great. Thanks, cody

[jasun]

The manifold and Riser work in tandem to keep the water out. there is a gasket that sits between the 2 of them. I noticed when I had mine apart that the riser is like a tube within a tube. The water ciculates around the outside and the exhaust is around the inside and right at the base of the riser (where it meets the exhaust pipe) is where they mix. If it is all sealed up well, then no water should be able to enter the manifold.
http://www.marineexhaustmanifolds.com/product_images/riser1.jpg

If you look at the bottom you can see where it is sectioned off so water can flow around the outside and exhause on the inside.

I had my manifold and riser off and ran a hose to it and plugged the bottom of the riser and only at that point would water come out the bottom of the manifold.

Hope this all makes sense....

[haugy]

Yep, Jasun has it. Basically they are separate until right before they hit the rubber exhaust tube. Now, if you have a cracked manifold, it could allow water into the interior channel which then could get back into the pistons from the valves.

That would be my first thing to check.

[wotan2525]

I would pull all of your sparkplugs and turn it over and see if water comes out. I assume you will have water coming out. This should at least allow you to crank the engine over and get a compression test done properly. Once that happens it is time for a leak down test.

It is possible that your exhaust manifolds are cracked, but even then -- it would be difficult for water to be sucked/pushed into the engine enough to hydrolock them.

You could pull the exhaust risers and take them to a machine shop to have them tested for cracks. They may be able to repair them or you may have to replace.

[DAFF]

Get the milky oil out of there as fast as possible. Inspect the gasket closely where the manifold meets the riser. Hopefully this is the region of the water infiltration. If not I would suspect a poor winterization. Once you solve the leak add new plugs, oil/filter perhaps 2x's and enjoy.

[csl]

Heres where we are at so far. After compression test looked ok, we added 10 lbs of air pressure to the water system. The pressure went down, but very slowly. This morning we filled the system full of water at 10 lbs and after an hour it was still holding and no water in oil pan. I have heard that sometimes the motor has to be warm to find the leak, so we flushed the oil and are going to add fresh and start it up for a bit and see if anything develops. We have tried to diagnose it some before pulling the heads and seeing what it looks like, but nothing is obvious so far.

[DAFF]

Get to the lake and take a lap or too. Check the plugs individually to see if there is any washing out from water or funny looking things. Make sure water is running through the engine especially at the risers by removing the 1" line running to each side. Who winterized the engine ?? Just wondering if there might be a internal crack of the block in the water jacket which opens up with heat.

[csl]

I did all the winterizing. I can't think that is the problem because I was very thorough with it and also the boat is stored in an insulated shop. Also I have had the boat out a few times already this year and ran like a top. At beginning of season I turned the boat on at the lake and noticed the impellor was backward. We shut it down right away. Temp got to 200. Reversed impellor and ran the rest of the day at 140 no problem. I hope I didn't do anything then, but that is the only time I have heated it up. Will give it a try on water and see what happens. Thanks

[csl]

Ok, we are stumped!! Changed the oil out tonight and ran on a hose. Got boat up to temp. and ran for a good while and we cant see a bit of water in the oil. All the guages are reading great, motor sounds great, compression is good, and i can't find a thing wrong. There was a significant amount of water in the oil after we broke down on the water last week. I tracked my starting issue down to the alternator. So that is answered. Can it be just a freak deal? That seems too crazy.