Milky transmission oil

[Beta Jockey]

I changed my gearbox oil last Saturday and it was milky grey. The oil had 300 miles on it.

I replaced it with fresh oil, checked my filler cap o-ring for cracks, which was fine, and did another 40-mile ride on Sunday. When I got home I drained the oil and it was starting to look milky gray again.

So I'm guessing that the oil is being contaminated with coolant. Could this be due to a failed water pump seal? Does that sound right to anyone? If so, how difficult is that to change out? Anyone have part numbers?

Thanks in advance.

[Sweepea]

Heard the same story at the shop yesterday when I went in chasing a strange noise (squeaking). The clue was they kept having to fill the radiator after every lap (10mi) on the hare scramble course. The culprit was the water pump seal. They think my squeak is a blown water pump bearing.

Good luck.

[Rabster 45]

I had the same issue with my 2018 390 but there is a post on here ( I think or another forum) about re routing the gearbox/transmission breather pipe which hangs below the motor meaning that if your in water(I was several times) it gets drawn into the housing. I rerouted the breather pipe up to the top of the bike and that solved the issue. I also changed to ATF for the gearbox something I had read about on other forums and this seems to be fine.

[Amurican Dirt Rider]

I had the same issue with my 2018 390 but there is a post on here ( I think or another forum) about re routing the gearbox/transmission breather pipe which hangs below the motor meaning that if your in water(I was several times) it gets drawn into the housing. I rerouted the breather pipe up to the top of the bike and that solved the issue. I also changed to ATF for the gearbox something I had read about on other forums and this seems to be fine.

This is the issue I had as well. Being able to suck up water. To the OP, do you ride through water crossings often? It may be a leak into the oil, but it may be this.

[Beta Jockey]

I had the same issue with my 2018 390 but there is a post on here ( I think or another forum) about re routing the gearbox/transmission breather pipe which hangs below the motor meaning that if your in water(I was several times) it gets drawn into the housing. I rerouted the breather pipe up to the top of the bike and that solved the issue. I also changed to ATF for the gearbox something I had read about on other forums and this seems to be fine.

This is the issue I had as well. Being able to suck up water. To the OP, do you ride through water crossings often? It may be a leak into the oil, but it may be this.

I know it's been two years since I started the original thread, but the issue I had was NOT coolant contaminating my gearbox oil. On one specific day of riding, not only did I do a lot of water crossings that day, but at one point the rear of my bike was stuck in some deep water. I was revving the gas trying to free the bike out of the water, and I most likely sucked up some water through the gearbox breather hose. After changing the gear oil a few times to flush out the contaminated oil and re-routing the breather hose, it's been fine ever since and I've not had that problem again. Bike has just about 4,000 miles on it now.

[Deck1]

I also had my gearbox oil get milky when riding in heavy snow conditions and creek crossings. In the snow, I got some moisture on crankcase side, as well. Although, I haven't experienced that problem since changing to the bling red anodized aluminum fill caps on both sides. At 165 hours on mine, now, with original water pump.

[oldman]

2019 500RRS 5000 miles
I have been noticing slightly milky transmission oil at changes for the last 2500 miles or so.
Since my bike has not been in any deep water and I occasionally have to add a touch of coolant I decided to check the water pump seal. I found the original seal to not be seated straight, cocked in its bore slightly.

I've run about 500 miles since replacement and so far all seems ok.

[reage]

12X30X7

[Muddaholic]

I have a 2017 500 rrs. I had to replace the Water pump o-ring @ ~1000 miles. No problem since then.