M920 winch oil getting in to transmission

When I got my M920, it had the transmission and winch oils drained. I filled them both up. Everything thing seemed fine until I tried using the winch to pull out a dozer that was stuck in the mud. The winch started working intermittently. I noticed that the oil level had gone below the lower sight glass. I didn't see any obvious leaks. I checked the transmission fluid level and it was way over full.
Any idea as to what seal needs to be replaced?

After looking through the manuals, I am pretty sure it is a bad seal on the hydraulic pump shaft to PTO. Now the fun begins in finding the seal. It looks to be a Cross pump, Cross seal part number 5A0009.

yep that is the only thing it could be, after taking mine apart more times than I care to mention I would think that it would be pouring out from where the pto meets the pump if that were the case, especially under pressure. I would loosen the two bolts that hold the hydraulic pump on and see if oil pours out when you break them apart or if there are signs of fluid passing through there, if that is not it than I would recheck fluid level and try it again.

Winch Hydraulic oil looks like heavy cream

I started this thread because the rear winch on my M920 was operating intermittently. I looked at the sight glasses and both of them were white, so I concluded that my problem was lack of hydraulic oil. I checked my transmission fluid level and saw that it was about 1 1/2in over full. Therefore, the seal in the pump must be bad, causing the hydraulic pump oil to go in to the transmission. (When I got the M920 in January, all the fluids had been drained and I had to fill them up).

So, today I was going to take the hydraulic pump out to have the seal replaced. When I disconnected the hydraulic line from the pump, to my surprise, I drained 40 gallons of what looked like heavy cream.

So, I really wasn't low on hydraulic fluid. The cream looking hydraulic fluid just looked like the white background on the sight gauges. I checked the transmission fluid. There is no sign of the white fluid in there, so I guess I must have just over filled it.

So now I guess I have at least two problems. The first problem is the white hydraulic fluid. I guess there was water in the tank. It must have been a lot for it to make that much fluid look as white as it is. I will need to figure out some way to flush the tank, motor, pump and lines. The second problem is the one I started with-- the winch operates intermittently. Since I already have two of the lines disconnected from the pump, I guess I will take the pump off and have it tested/inspected. If that is good, I guess I will need a way to test the winch motor.

They will operate intermitantly if you don't have the PTO engaged 100 % There a pain to get fully engaged . You really got to pull up on the knob until you feel like a second click .Thats probably what it was.

Thanks to R Racing, think I will just try and flush the hydraulic system and try it again, making sure the PTO is fully engaged .
As far as flushing the system, my plans are to disconnect all hoses that I can and drain as much of the milky stuff out. I ten plan to put in about 10 gals (or whatever it takes) of the cheapest hydraulic oil I can find and run the winch, with the pump return line hanging in a bucket(s). Any other ideas would be welcomed.

jamboly said:

Thanks to R Racing, think I will just try and flush the hydraulic system and try it again, making sure the PTO is fully engaged .
As far as flushing the system, my plans are to disconnect all hoses that I can and drain as much of the milky stuff out. I ten plan to put in about 10 gals (or whatever it takes) of the cheapest hydraulic oil I can find and run the winch, with the pump return line hanging in a bucket(s). Any other ideas would be welcomed.

Click to expand...

that sounds about right for a flush, then change filter and refill.