i have cat 953c. i can not get it to move when i put it in forward or reverse the charge pressure light go on every time. when engine at idle the charge pressure at 70psi and at full throttle 300psi. the book said charge pressure need to be at 415psi. i know the charge pressure is dumping pressure to somewhere i don't know. when i try blocking off the 2 main lines to the drive motor. then the charge pressure go up to 410psi then it slowly go back down. i can not figure out where it is leaking to. i have 3 caterpillar dealer technician they could not tell me what is the problem. one technician is the charge pump then i bought new charge pump same problem, wasted $1200 on pump. check main relief valve too. valve seem to move freely. can anyone help me. thank you in advance
Have you checked the charge pressure relief valve ? it is a cartridge type relief valve, you could have some bad seals on it.