Hydraulic pressure relief? B series

[Grubs]

Hydraulic fluid in my engine oil...need ideas.

I have an ongoing problem with my B1750.

Hydraulic fluid from the hydrostatic trans is being pumped into the engine oil during operation.

I've had the dealer out twice to replace the seal on the hydraulic pump shaft as this appears to be the only point of separation between the hydraulics (3PL and power steering - no FEL) and the engine oil (the hydraulic pump bolts directly to the engine block).

Still the problem isn't fixed - after 4 hours operation the Hydro fluid is at the bottom of the dipstick and the engine oil is over-full by 1" on the dipstick.

My question - if there was a problem with the hydraulic pressure relief is it possible that high pressure in the hydraulics could go un-noticed and cause hydro fluid to be pushed through the hydraulic pump oil seal? - am I clutching at straws?

I'm at a loss... my dealer seams to think the seal is the only possible point of failure. The shaft that goes through the seal seems to have minimal wear and feels tight when being assembled. The tractor has done 1050 hours. The next step appears to be replace the entire pump and just hope that fixes it... $600+ is a lot when the diagnosis is to "hope" it fixes it.

Any Ideas?

 

[kennyd]

Frustrating problem for sure...

It would not hurt to check the system pressure-it's about the cheapest thing to do at this point-a gauge sells here for under $20USD.

I also believe like your dealer that the pump seal is the only point of failure-but I don't think it is the transmission as you you stated because it has it's own pump...the pump on the engine is for the 3PH, steering and any other auxiliary hydraulics.

 

[Grubs]

Thanks kennyd - my understanding is the same. The hydraulics have a separate pump bolted to the engine block but it uses the hydrostatic transmission as the reservoir for the hydraulic fluid. The upshot being that as the hydraulic fluid is leaking into the engine oil the level of fluid in the hydrostatic transmission goes down.

When I first took delivery of the tractor (at 1000 hours) the engine oil over-flowed in just a few days and was spewing out the rocker vent. After replacing the hydraulic pump seal the first time the rate of hydraulic oil ingress into the engine was slower with 2-3 litres (1/2 gal?) getting past the pump seal in 20 hours operation.... again the pump was removed and yet another genuine seal was installed... but the problem remains and might even be leaking faster this time around. Very frustrating as when the pump is disassembled the seal friction and fit appears to be good.

 

[tmthunder]

I would check also to make sure that the previous owner did not cross a vent line somewhere on your tractor.