Case 780CK migration of hydraulic fluid into transmission.

[Leckster22]

Had a bit of an issue this summer placer mining with my Case 780CK (We used it for just feeding the wash plant)

One night I noticed that hydraulic fluid was coming out of the pressure relief valve for the transmission on closer inspection I decided to drain the transmission from the upper fill bolt, I drained about 7 Gallons of Hydraulic fluid.
Then I checked the Hydraulic Tank and it was showing low, I proceeded to refill the Hydraulic tank and continue on running and for the rest of the month after about 15 - 20 hours of running would have to drain the Transmission and fill the Hydraulic Tank.

My question is:
Is it just the seal/gasket between the Transmission and the Hydraulic pump that needs replacing? or do I either need to rebuild the Hydraulic Pump/Buy a new one?

If it is a seal or gasket where could I either find a seal kit or gasket kit for it?

on a side note we had the engine completely rebuilt 3 years ago and love the machine! I can sluice all day with it on less the 10 gallons of fuel!

 

[Tinkerer]

You are correct about the pump. It is the only link that I know of for the hydraulic oil to get into the transmission. Most likely the seal only, but the input shaft bearing could be defective and alow the the shaft to wobble.
Here is a screen shot for a 780C model pump. Be very sure of which model you have. Case badged a lot of T/L/B's as CK's. Here is a link to the photo source.
https://partstore.casece.com/us/par...l=EN&currency=#epc::mr65623ar1104636bi2054429

 

[Leckster22]

Thank you Tinkerer for the reply and the information I'll be looking into this asap

 

[James Madigan]

Hopefully my problem is the same.im gona try to get the seal kit.Did anyone ever hear of a compressor base for sale