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New member
BillR

Re: D9H Hydraulic Fluid Tank Overflowing and Leaking


ColbyDorroh wrote:

We bought a D9H over the winter to level out a 50 acre field that we plan on putting back into crop production.

When we first started using the dozer, we noticed that it was building a lot of pressure in the hydraulic fluid tank. We discovered that some parts were missing from the cap, making it unable to vent any pressure that builds. These parts were replaced, and now the cap vents. However, any time you lower the blade a large quantity of hydraulic oil squirts out the vent hole on the cap. The level was right in the middle of the sight glass with it running and the blade lowered, so it doesn't appear to be overfilled. Last time I ran it for 4 hours, and I bet it lost about 2 gallons of fluid in that time. My suspicion is that previous owners were having this problem, so they just removed parts from the cap so that it wouldn't vent, essentially sealing it off. We were concerned that could be dangerous without a way for that pressure to vent from the tank. Any idea why this is happening or a possible fix?



Colby: I believe the hydraulic tank on the D9H should be pressurized and not vented. Most all CAT hydraulic tanks except off highway trucks have a pressurized system. This pressure keeps the dirt out and helps maintain oil in the suction line for your hydraulic pump. The system does have a vacuum breaker much like a radiator on a car that will draw in outside air as the system cools down. If your cap is vented, I think that is your problem and why you are pushing oil out of the system. My thought, get a new pressurized cap.

New member
ColbyDorroh

D9H Hydraulic Fluid Tank Overflowing and Leaking

We bought a D9H over the winter to level out a 50 acre field that we plan on putting back into crop production.

When we first started using the dozer, we noticed that it was building a lot of pressure in the hydraulic fluid tank. We discovered that some parts were missing from the cap, making it unable to vent any pressure that builds. These parts were replaced, and now the cap vents. However, any time you lower the blade a large quantity of hydraulic oil squirts out the vent hole on the cap. The level was right in the middle of the sight glass with it running and the blade lowered, so it doesn't appear to be overfilled. Last time I ran it for 4 hours, and I bet it lost about 2 gallons of fluid in that time. My suspicion is that previous owners were having this problem, so they just removed parts from the cap so that it wouldn't vent, essentially sealing it off. We were concerned that could be dangerous without a way for that pressure to vent from the tank. Any idea why this is happening or a possible fix?