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catmastertech, Technician
Category: Construction and Road Equipment
Satisfied Customers: 2343
Experience:  Field service technician for CAT 19 years.
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HELP PLEASE cat 315 main pump i have some problems with

Customer Question

HELP PLEASE cat 315 main pump
hello i have some problems with a1996 cat 315 i just installed a new engine and repack the main hyd pump i didnt see anything wrong with the pump, but machine when i start working engine dies, when i reléase the controls gain power again, i checked my pump pressure loading and it is 2750 psi do you know if that pressure is good or if it could be anything else.
Submitted: 1 year ago.
Category: Construction and Road Equipment
Expert:  catmastertech replied 1 year ago.


Have you tried using the backup switches? This may help if the electronics are an issue.

Is the PRV pressure working correctly? It will change when a load is applied and electronics are working.

I am guessing all hoses were marked and installed back to the correct ports?

The pumps should make 4500 psi. If engine is weak, you will not get to that pressure.

Are you sure the engine is correct and running at full power?

Customer: replied 1 year ago.
hello and thanks for the quick response, i just replace the engine rebuilt fuel pump and nozzles, someone here in mexico that my pressure on the pump is fine i have 2700psi in one pump and 2700,psi on the other pump i am new in excavators i repackked the pump and both pumps didnt show any sings of wear, i tried the switch that are on the right elbow by choosing in manual and at high idlle not the turtle engine only diez when i start excavating and some times when i put arm up and push the stick back engine dies, and when i try tu lift the machine just go up like 20cm, but engine doesent dies in that move dont know why, is there another switch on the left elbow also?
Expert:  catmastertech replied 1 year ago.

If this is an earlier model, yes. The left console has the pump backup switch. This will bypass the controller and operate the pump at about 70 percent power.

Is the PRV pressure working correctly? (Sometimes this is called powershift pressure)
Were all hoses marked and installed back to the correct ports?

What is the full machine serial number? (PIN)

Customer: replied 1 year ago.
it is an early model machine is like 1995 year serial is 6xm00281t fine is japanesse machine i get the parts from 6ym serial and fit just fine, also they told me that i have to add together both pressures of both pumps is 2700psi in each pump is good? havent checked prv preassure where is that port and what preassure shoud i get and yes the hoses are just fine havent moved them
Customer: replied 1 year ago.
by dding both pumps pressures i mean to get the 5000psi is that correct?
Expert:  catmastertech replied 1 year ago.

No, the pressure should be 4500 psi from each pump separately. The flow is combined to increase speeds, pressure will remain the same and does not combine.

PRV, powershift pressure is the third port tap on the pumps. Follow the line from the solenoid attached to the pilot oil manifold on the forward side of the pump compartment area. This line should connect to one pump control head and have a tee with a line to the other control head. A pressure tap port should be near this hose. Pressure should be about 350 psi and drop to around 100 psi when pump is loaded. When pump control bypass switch is on this pressure will remain around 300 psi.

If 0 psi, check for power to the PRV solenoid.

If this is normal, engine power is likely the problem.

I am signing off at this time. If you need more help, I can be back here tomorrow night. If this is not helpful, I will OPT-OUT so others can see your question and help.

Customer: replied 1 year ago.
ok thanks i will check tomorror the preassure and let you know
thanks have a good night
Expert:  catmastertech replied 1 year ago.

Thanks, ***** ***** be looking for your reply.

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