why is my outdrive oil look milky

[eta1091]

My  cvx20 has been running like a top so far this year up north in Alaska. I noticed some noise in my out drive the other day. its an alpha 1 gen 1 mercruiser. I drained the oil and I had water in my oil. So I puled the lower unit off and checked my water pump and all looks good, hooked up a pressure gauge and it holds pressure. Pulled the upper and did the same and found that the input shaft seal was leaking and I had a lot of oil (brown/white ) not white like in drive in my bellows. I replaced the seals in the carrier and pressured the unit and it was holding psi. I thought I was all good to go. put her back together filled with oil and went to the lake. after 3 hours of running at the lake I checked the oil and its white again. I pressured the unit and its not leaking. where could the water be coming from? I am thinking of replacing the oil and running with the ear muffs to see if it has to do with the water pump passages. any clues to what it may be?
thanks a lot.
Eugene

[Retro Performance]

I think pressure testing tell you if it will hold oil in...........I think you need to do Vaccum testing to see if it will hold water out..........

[Rich_V174SS]

In addition to pressure testing you also have to vacuum test it. Pressure test it to 15psi and it should hold for days. Move any of the shafts and listen for the leak. There's any number of places where the water could be getting in - through the seal in the baseplate under the water pump, prop shaft (especially if there's fishing line caught around the shaft), shift rod seal, upper vertical shaft seal, and either of the two oil plug gaskets.

[eta1091]

vacuum testing? hmm good idea, I have never even heard of that before. Maybe a brake bleeding pump handle type of tool?
Thank you
Eugene

[Rich_V174SS]

A drive vacuum tester looks exactly like the pressure test tool, except you pull the plunger to create vacuum in the drive instead of push to create pressure. The reason you vacuum test it is while a shaft seal may hold pressure in one direction that doesn't mean it will hold in the other. As hot drive oil cools and contracts it can draw water in through a seal into the drive, it doesn't necessarily mean you're going to lose oil as it expands. But you have mentioned you needed to replace the upper yoke shaft seal because you were getting gear oil into your bellows. Touching on that for a moment - I just replaced one for a customer of mine but in addition to the seal I also had to replace the short end of the yoke that goes through the seal and into the bearing pack and pinion gear. The seal had worn a groove into the surface of the yoke so just replacing the seal may not be enough to fully seal that joint. It could continue to leak because of the worn groove in the yoke.

[eta1091]

Thank you! I have narrowed it down to water pump area, tell me if I am on the right track. I changed or put in new oil. put on the ear muffs, turned the water on and ran the engine for 5 or so minutes. the oil is white again. I am suspecting the path of the water from the bottom of the drive up to the pump area is going to be my problem. I replaced the pump this spring.

Additional info. we tried out this hi speed 2 blade 26 pitch stainless prop. The experiment was my first and last with that sort of prop because for what ever reason the engine over heated badly. I thought maybe we burnt the water impeller during this experiment. when I replaced the seals in the out drive I visually inspected the pump and it looked great. I am suspecting there is a ring seal, or gasket underneath the pump that may be the problem.

Thank you
Eugene

[Rich_V174SS]

If you're getting water in the oil just by running it on the hose and ear-muffs then it's a good bet the pump base seal is your culprit, replace the base with a new one.

Using a larger than spec prop will not cause your engine to overheat that badly, maybe a few degrees if the engine is working extra hard but it shouldn't cause things to get so hot you can't touch them. I suspect you probably have an aftermarket water pump impeller like from Sierra which are notorious for spinning free from their brass hub. This results in a lack of water being pumped to the engine. If you look at the impeller you may think it's ok from a visual standpoint but the rubber could be delaminated from the hub. Stay away from them and use only Mercury OEM pump kits where the impeller has a fiber hub, you can't go wrong with them.