water in lower unit

[Bullsey398]

I just picked up an older Merc 20 hp on a duck boat. I've now found that the gear lube in the lower unit is milky indicating water has been getting in.

My question: Is the likely source of the leak, just the prop shaft seal, or could water also get in from the water pump? Any other leak sources?

Thanks!
Greg

[Gone Fishing]

It could be either the prop shaft seal or the seal at the water pump. Those are the 2 prime candidates for water intrusion. I would think replacing those seals would eliminate the problem. Good luck!

[andy capp]

I had that problem on my 70 hp johnson I took it in and the guy found nothing wrong. In a pressure check it is supposed to hold 5psi for 15 minutes, mine held 15 psi for 2 hours. Indicating nothing wrong. New gear oil will mix with the old and it will lighten up some. If you want to see if you are getting water in there, if the motor is on the boat, let it sit for 2-3 days without running it, Just crack loose the top drain screw, then loosen and take out the lower. Water sinks in oil and it will seperate. When you take out the lower solid water will come out. Dont look for a waterfall it takes very little water to turn the fluid colors. But that is how you can tell.