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The pressures are 460 pilot and main is around 4600. the pump…

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The pressures are 460 pilot...
The pressures are 460 pilot and main is around 4600. the pump has been rebuilt and set to spec buy the Cat specialist about 40 hrs ago. The staling under load appeared 1st ,the machine sat for about 1 month because of extreme rain. now my operator went to start up the machine and the left track was slower. we have gauges and a service manual. I need the part number for the line crossover relief valve. the part number for the cooler line bypass valve. Follow the big line from the top of the swing motor to the aluminium block near the cooler. There are two big check valves inside it. The Slow Return Check Valve that holds a back pressure on the return to tank oil to prevent the swing motor from cavitating when coasting to a stop. The other check valve is the Cooler Bypass Valve. It allows cold oil to bypass the cooler rather than dammage it from overpressure. Either of these check valves can back out and not open enough to operate correctly. the machine is a 330BL 6dr2055
Submitted: 9 years ago.Category: Construction and Road Equipment
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Answered in 5 hours by:
11/26/2012
Mechanic: Steve, Mechanic replied 9 years ago
Steve
Steve, Mechanic
Category: Construction and Road Equipment
Satisfied Customers: 104
Experience: Heavy Equipment Mechanic for 25 years
Verified
Hello, my name is Steve and I may be able to help you out. I can get you the part numbers that you need if that is all that you are looking for or I can help you troubleshoot the problems that you are having with the machine. It sounds like you are fairly familiar with the hydraulic system, I would check the power shift pressure and make sure that it is moving up and down according to engine load, then check the engine rpm and make sure that it is reaching high idle. Is the left track slow in both directions or just one direction?
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Mechanic: catmastertech, Technician replied 9 years ago
catmastertech
catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 3,994
Experience: Field service technician for CAT 19 years.
Verified

Hello again, I remember the serial number but, I don't have access to the earlier repairs. Did this machine have travel problems earlier?

When the check valve backs out, the most common problem is jerky operation in high flow functions. A common complaint is the stick is fighting itself to move in or out. This is due to the flow being stopped and then released by the loose check valve.

Have you re-sealed the swivel (rotary joint) in the center of the machine? I think we had talked about this before.

The part number for the counter balance relief valve located in the travel motor is 129-8030

The oil cooler bypass valve is part number 094-6526.

The slow return check valve assembly is 142-5516 and the check valve itself is 142-5517.

The normal pilot pressure is 595 psi, main relief is 4950. I think you are reading PRV powershift pressure, it is around 460 with the pumps in standby or under full load. When the machine implements are moving, it will fluctuate to prevent excessive loading on the engine.

Pilot pressure is checked at the fitting on pilot manifold where the solenoids are mounted. The fittings on the pump are pump output pressure and PRV powershift pressure.

Let me know what you need help with, I will be glad to help you anyway I can.

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