water in lower unit?

[coreynov902]

1999 175 EFI (serial #0G944199)...like an idiot, when I was winterizing my boat this fall, I completely forgot about draining the lower unit lube and re-filling it. Not sure how I forgot, but I did. I remembered it the other day when I was in the garage, so I wound up doing it yesterday. When I drained the lower unit, the gear lube was marbled, with some a milky color and the rest a darker gray/green color. I've seen photos and videos where all of the lube is milky colored, but mine was not. I'm not sure whether that just means I had a little bit of water in the lower unit or if it's common to have some of that marbling? Any idea how worried I should be about this? The garage is not heated and because we had -20 to -35 degree weather last week, my garage temps did get down into the low 20's. Is there a way to tell whether damage was done without taking it in and having the lower unit removed and inspected? Any help would be appreciated. Thanks.

[SilverFox579]

Is there a way to tell whether damage was done without taking it in and having the lower unit removed and inspected? Any help would be appreciated. Thanks.

Since you had moisture intrusion before the cold spell, best course of action is to pull the lower unit and drop off at a well qualified shop for testing.

[coreynov902]

I have read that when the motor sits for a while, the oil and water will separate and the water will sink below the oil so that when you take out the lower unit drain plug, water will come out first before the oil starts to come out. I did not experience this with my motor, which has been sitting for three months now. Do I have reason to hope that the water intrusion was very minimal since I only saw some milky colored marbling in the oil versus water draining out when I drained the lower unit?

[EuropeanAM]

It "sounds" like it's minimal, but it would be very wise to have the gearcase pressure tested (and replace the drain plug/vent screw seals at the very least, if no leaks are noted).

[coreynov902]

thanks for the replies. I have already contacted my local marine tech to see what he thinks and also to get a couple new gasket seals for the drain plugs.

[SilverFox579]

[kylelp]

This sounds like mine last boat lower unit oil. I didn't really have much "marble" but it was a different color and thicker than fresh oil. I took it to the local shop, they said seals looked good & you will always get a little water intrusion. He did pressure test and it held up good. I would do a pressure test which will tell you for sure.

[xcoach]

I know I am overdoing it but when I replace lower unit gear oil every spring I buy new screws and seals, not worth risking water damage.

[coreynov902]

Thanks for all the input, it's been very helpful. I'm waiting to hear back from my local boat mechanic, but I'm hopeful that in the end no major damage has occurred and I just had a minimal amount of water intrusion that new drain and vent screw seals will fix.

[Pecos23]

Thanks for all the input, it's been very helpful. I'm waiting to hear back from my local boat mechanic, but I'm hopeful that in the end no major damage has occurred and I just had a minimal amount of water intrusion that new drain and vent screw seals will fix.

I wouldn’t worry too much about a little marbling in the oil. The water will separate and lay below the gear lube. If you had enough to worry about, it would have poured out before any lube drained out. Especially after sitting so long.

Have the shop do a quick pressure check, doubt there’s any problem, and replace the screw seal.
Marine gear lube is different from auto lube in that it is formulated for water contamination. Your main concern is corrosion, but it didn’t set long enough to rust anything in a bath of lube.

[Bruce2]

I had marbling in my gear oil on my 1995 merc and I pulled lower unit and had it resealed and water pump done for 350 bucks figured seals where 23 years old and it was time, pay now or pay later. That's some cheaper than a 2500 dollar lower unit

[JOE54]

^^^^ agree ,and that was money well spent