1500D

DavesTractor · Aug 18, 2007

DAIRYMAN said:
In a jam. I have a YM-1500D witha front end loader. It has been great for the last 5 years I've had it. About 2 weeks ago, I noticed transmission oil in the crankcase. I replaced the seal on the pump, thinking this was the only place for fluid to come from. Worked for another couple hours, and had fluid in the crankcase again. I broke down and bought a new pump, and after about 3 hrs of use, again, I had fluid in the crancase. Anyone have any thoughts or ideas? I don't think it's a pump problem, but what else could it be? Maybe backpressure?

Thanks

Looks like you have though this through. One idea would be to test the relief pressure. What if it is 3500 psi, instead of a more reasonable 2000 psi? It might be just high enough to force oil out the seal, but not quite high enough to shear the keyway or bust the pump. Unlikely, but an idea. The other thought is that the new pump is actually bad around the seal. What are the odds?

HoyeTractor · Aug 20, 2007

DairyMan,
We have actually received a lot of calls about this exact type of thing in the last few weeks (around 5 or 6 different people). Mostly on YM1500s 2000s, etc. I was happy to see your post here & thought someone would have an answer for you/us. Since you did not get any " I know exactly what is wrong..." answers I'll tell you what we found so far.

We have had customers with no loaders that have both the original pump & the replacement pumps start leaking large amounts of oil into the crankcase. At first we thought it was just an isolated incident but the calls kept coming. We have tried Yanmar brand replacement pumps, Japanese made aftermarket pumps, & even one of the Chinese aftermarket pumps on different tractors and they all leaked. I do not think it is a problem with the pump.

I called one of the pump manufacturers and they said that the pump shaft seal will normally see around 3-5psi and the seal will hold that amount of pressure. The only thing he could think of that could cause that to leak is pressure in the suction line or too much back pressure in the high pressure line. I agree with you and don't see how you could get pressure in the suction line on a Yanmar with the rubber shifter boot. I know that can't hold 5psi. So, according to the manufacturer, that leaves too much pressure in the high pressure line as a cause .

I agree with Dave. I would recommend one of our hydraulic pressure test kits here-->

Hydraulic Pressure Tester: Yanmar Tractor Parts

to see what your pressure readings are. We rent them now for $10.

I guess it could be that some tractors are now getting replacement valves during the import process that have too much relief pressure?? Please keep us posted if you find a cause.

Aaron
(940)592-0181
Parts@HoyeTractor.com