Transmission fluid looks like Strawberry milk

[megapea]

I have a 1999 Mastercraft 230 VRS Maristar with the LT-1, and 630-V Hurth transmission. I bought it last fall and changed out all the fluids with synthetics. I've been running it quite a bit this season, and everything has been great. This past weekend I noticed that the tranny wasn't engaging reverse before the throttle started increasing. I figured that the tranny cable needed a little adjustment. I took a look today, and adjusted the cable, and figured while I had it all opened up, I would do another fluid change (Mobil One ATF) on the tranny. When I opened the filter lid, I was surprised to see my fluid looking like strawberry milk! How do you think the water got in the tranny? We did have some hard rains over the weekend and the bilge was pretty full in the morning ( I had it docked on the lake ) until I pumped it out. Is there a vent, a seal, or somewhere the water could have gotten in, or might it be the tranny cooler? I did winterize it last fall, and it was in heated storage, but do those coolers sometimes just fail? I have 498 hours on the boat. Any advice would be appreciated!

[oldairboater]

Sounds like to me a full bilge put water in your transmission. I had the same problem when I bought my boat. Previous owner had filled the bilge and water seeped into my transmission. I don't know for sure but I bet the dipstick has a vent built into it. The only other way would be from your transmission cooler and I doubt that is your problem. You need to quit storing water in your bilge.

[Craig]

There is a vent on the housing to prevent overpressure, IIRC.

If your bilge was really full it could have gotten in there. Your tranny cooler could have a crack in it, did you remove it and make sure you got all the water out when you winterized? If there is a little bit of water in the bottom of the cooler it can separate the brazed joints inside the cooler. You can have it pressure tested at a radiator shop.

The last option is a tranny seal, that is probably the last place I would look.

Start by replacing the fluid and running it for a day or so. If it looks milky again, you know it wasn't the vent (assuming you don't let the bilge fill up again), it is probably the cooler, get it tested. If not, probably the vent.

If the cooler passes the pressure test, investigate the seals.

Whatever you find out, change the fluid twice (AFTER you find the problem) to make sure you get all the water out.

[Jorski]

Assuming everything is fine with the transmission and the cooler...it will take 6 or 7 fluid changes to get all of the water out.


I had the same thing happen to me last summer...cover blew off, lots of rain...and a hose jammed the float switch for the bilge pump in the off position.

Run it, change the fluid, run it again, change it again....lather rinse repeat until fluid doesn't turn pink and milky.

Also, on my transmission, the dipstick plug, can be tightend by twisting the t-handle, which squezzes a rubber bung making a much tighter seal.

[megapea]

When you say change it out, do I vacuum all the fluid out, refill, run engine a little (in the driveway with Perko valve & hose), and repeat this procedure several times, or should I run it on the lake inbetween flushes? Does it damage anthing in the tranny with that water mixed in with the fluid?

[2000205V]

A few years ago this happened to me. Because there is a negative pressure in the tranny when running, it will suck water thru the lower seal into the transmission fluid if the water level in the bilge is up high enough to submerge the seal (it doesn't need to be too high - 2-3" of water will do it).

You can also easily burn your lower seal if you run it submerged for too long (what happened to me). If you have no transfluid in the bilge the seal is likely OK. If the water is high enough to reach the dipstick/vent you'll have other engine issues as that level would be upto the floor boards and halfway up the engine.

I installed a second bilge pump in the rear of the boat with a separate float switch after I had to pull my transmission to replace that seal. It was a big job to do in my boathouse.

Change out the trans fluid again, and keep an eye on the bilge level.

[Jeff d]

I just went through this on a '00 230 VRS that I bought that had high water in the bilge.

It took 3 changes to get all of the water out. I went to 15w40 motor oil per the attached Indmar service advisory at that time too.

The first change I pumped all of the ATF and water out, drained the cooler and the lines then refilled with 4 quarts of 15w40 Mobil Delvac. Without running it I let it sit for a few mins and pumped that new oil right back out. It went in a translucent, golden brown and came out looking like caramel. I refilled it again and took the boat out for a couple of hours. I came back and changed it again and it looked somewhat opaque. Took the boat out one more time yesterday and then took a sample of the oil tonight and found no signs of water so I think I'll leave it for the remainder of the season but will definitely change it again before I winterize.

Cost me about $35 in oil but I'm glad I found it and changed the oil before running it too long because that would have cost a lot more. Not sure if there will be any lasting damage because I'm unsure how long the water was allowed to sit in there.

[Jeff d]

BTW the 15w40 did quiet down the transmission. Not that it was objectionably loud before or anything.

[megapea]

I read the Indmar service advisory too, but am a little reluctant to change to the 15W40 oil. My tranny is a little "whinny", but is not objectional. Has anyone had any "ill effects" from changing to the oil vs Dextron III? It sure would be a lot easier to only have to buy one product for both! My reluctance stems from the advisory coming from Indmar (the engine mfg.), not Hurth (the tranny mfg.).

[Jeff d]

I read the Indmar service advisory too, but am a little reluctant to change to the 15W40 oil. My tranny is a little "whinny", but is not objectional. Has anyone had any "ill effects" from changing to the oil vs Dextron III? It sure would be a lot easier to only have to buy one product for both! My reluctance stems from the advisory coming from Indmar (the engine mfg.), not Hurth (the tranny mfg.).

Well, supposedly the boats released after the service advisory spec'ed 15w40 from the factory. I guess I'm putting my faith in Indmar/Mastercraft and some of the other posts on this board. Researched it a little bit before making the swap and didn't see anyone mention any ill effects.

Is the ATF in our transmissions acting as a hydraulic fluid as it would be in an automotive automatic transmission? Or is it only a lubricant? I think the latter is the case so I can't imagine it being too picky about the viscosity of the lubricant as long as it's within reason. I could see where replacing the ATF in a car's automatic transmission potentially causing major problems but here all it needs to do is minimize wear.