Lower Unit Fluid

[Mike2718]

2003 XR6
Serial: 0T759783. Model: 1150454AD

My nephew was doing his annual maintenance and this is what came out of his lower unit. It's not the normal milky color you would see if there was water in the oil. It looks like some type of sludge but I'm not sure. I have never seen this before. He uses Mercury Hi Performance lower unit oil and changes it yearly.
Thanks

[20DC BULLET]

It's water....Pull the lower unit, reseal it, and put a new water pump in while you're there.

[OldTimer57]

Agree. It is water. Just not much water. Fortunately you caught it way early before anything was damaged. Water doesn't mix with synthetic like it does with the older Dino oils. It just emulsifies into that kind of stuff and most will eventually separate and sink to the bottom.

[Mike2718]

Thanks Bullet and OldTimer. I kinda figured that's what it was going to be. I couldn't imagine what else it could have been. Now at least I know for future reference. This "OldTimer" just learned something new too. It used to be my boat until I gave it to my nephew a couple of years ago. He's on his 2nd oil change. I always used Hi Performance Lube in it too. I have been lucky that I have never had water in the lower unit. I always changed it every year too. I also changed the water pump every year or two at the max. My nephew lives 6 hours away & we were already planning to meet half way so I could show him how to change the water pump. I just hope it's not leaking at the prop seal. I will pressure test it when we drop the lower unit & pinpoint where it is leaking. This will be his first time to change it. I told him that if he keeps up with all the necessary maintenance, that boat and motor should last him a lifetime or at least until he is ready to buy a new one.
Once again, thanks guys for the info.

[SilverFox579]

That's not much water might just be from a bad drain plug seal or a doubled up one.

[Bruce2]

I had a little bit of water in my lower unit(about that much) and went ahead and had all seals changed since it was a 1995 merc...I figured one seal leaking today and then next week another one so might as well get all of them done and get it over with.

[billnorman1]

Pull the prop. Inspect the seals behind the prop very carefully. If there is any line on the prop shaft, count on changing those seals.

[Mike2718]

Pull the prop. Inspect the seals behind the prop very carefully. If there is any line on the prop shaft, count on changing those seals.

We had to replace his prop hub not too long ago. It didn't have any line wrapped around the shaft and it "looked" ok. I will pressure test it when we drop the unit. I will spray soapy water around the prop shaft & other spots to see where it is leaking.
SilverFox, I told him to go ahead and get new seals for the vent plugs. I'll tell him to make sure he didn't double them up. I know they are only a year old but I told him to get new ones anyway. I used to change them every year. They're cheap so it won't kill him to change them every year too.

[SilverFox579]

SilverFox, I told him to go ahead and get new seals for the vent plugs. I'll tell him to make sure he didn't double them up. I know they are only a year old but I told him to get new ones anyway. I used to change them every year. They're cheap so it won't kill him to change them every year too.

Good decision, the blue fiber seals should be replaced every time the drain plugs are removed.