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Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 5570
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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Transmission oil level overflowing..., hydraulic oil leaking

Customer Question

transmission oil level overflowing..., hydraulic oil leaking into transmission on CAT IT14F wheel loader..., what component has most likely failed, and what is the best approach for repair?
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  Dan replied 1 year ago.

Hi my name is***** would mean a hydraulic pump failure requiring a replacement hydraulic pump. Clean/flush the system oil and components and replace the filter. check inside the old filter for fine metal debris that would tell you if the system is badly contaminated requiring extensive flushing and cleaning. Remove and install the pump with new o rings and seals. Fill the oil to capacity and run and check for leaks. Let me know

Customer: replied 1 year ago.
apparently there are two pumps..., one is the main hydraulic pump (which lives outside the transmission), and the other pump (purpose unknown) actually lives in the transmission. this is the pump that we suspect has a leak...i'm assuming there is plumbing and connections that link these two pumps together, and while i would also call into question the wisdom and logic for hiding the main hydraulic pump inside of a transmission (with its own separate oil supply), i'm guessing the engineers had a reasonable motivation to do so...Dan, i'm not sure if the damage/ failure will be self evident, but our plan is to remove suspect pump and inspect for damage..., and i was curious if there could be something else besides this gear pump that could explain the unwanted transfer of hydraulic oil into the transmission reservoir???i've got the parts guy from NC machinery ready to sell us a new pump..., but i hate to start off the project by merely replacing parts...., as this could get expensive...i was looking for some specific detail in identifying and ordering all of the correct parts that we might need, especially considering the immediate need for the repair and the remoteness of the job site/ location...therefore, any further insight and advise (especially in eliminating other possible sources of leaks) you could offer would be greatly regards,Rod
Expert:  Dan replied 1 year ago.

Thanks for the update Rod, What is the complete model and serial number of this machine? IT14 has a hydrostatic drive transmission with a pump and drive motor. Let me know

Customer: replied 1 year ago.
IT14F is the model, and the serial is 4EL00292from what i can gather, the gear pump (likely leaky suspect) controls the steering and brakes, while the other pump controls the implements...what i'm still a little hazy on is the plumbing that these two pumps share (obviously they share oil from the same hydraulic reservoir), and i suspect that the gear pump (controlling the steering and brakes) is somehow responsible the excess/ overflowing oil in the transmission now...curious if there's an field test we can perform to isolate/ pinpoint the source of this mystery leak, and if it truly is the gear pump (as i suspect), what are the proper steps to go about in accessing it.just to add a bit of recent maintenance history to this machine, the brake boost cylinder was recently changed and it appears (from service diagrams) that these two separate hydraulic pumps may share an additional "oil connection" IF there was a failure within the brake booster assembly??? granted this may be kinda out there, but i really wanted to eliminate as many other possibilities b4 we tear into the,Rod
Expert:  Dan replied 1 year ago.

Hi Rod, Thanks for the update. This machine has a hydraulic pump and then a steering/brake pump on the end. The main implement pump is driven off the transmission gear pump ( Charge pump) which utilizes the transmission oil to supply the transmission. It would be the hydraulic pump driven off the transmission charge pump that is leaking through the transmission charge pump into the transmission.