I have a Cat143h motor grader that keeps blowing the front seal out of the All Wheel Drive Pump and blowing hydraulic fluid into the engine. I have ran through the flushing and cooling control valve testing sequence; by testing the charge pressure sequence valve it tested at 400 psi it is supposed to be 435 +/- 10 psi; I also tested the purge pressure sequence valve it is at 300 psi and is supposed to be 290 +/- 10 psi (so I know it is within spec but closer to being out of range than not). I also removed the inline hydraulic filter and found pieces of aluminum inside. I would imagine their is a relief valve somewhere in the system but I don’t have access to it. Can someone please help direct me in the right direction?
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Cat 143H All Wheel Drive Pump
- Thread starter Mears1
- Start date
Nige
Senior Member
Serial Number..? With that I can find a hydraulic schematic that might help you.
John C.
Senior Member
The first and and most common reason for blowing fluid out the input shaft of any pump is high case drain pressure. High case drain pressure can be caused by a worn pump leaking fluid past the pumping elements and into the case drain. You could also have a case drain hose crimped or kinked by something. You might have a piece of trash stuck in a case drain fitting somewhere as well. A couple of other issues could be bad pump bearings, worn input shaft and possibly a bad pump casing.
Thank you for everyones help, sorry for taking forever to get back to everyone I was dealing with wheeler on their shenanigans. Apparently Cat changed the porting inside of the pump and never told us when they sent the new pump out. The original pump lasted over 4,000 hours so not sure why they wanted to replumb it. The new pump calls for a case drain to be installed and teed into the fan hydraulic return line.
Nige
Senior Member
You mean this update..?