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CAT 302.5 recently had a drive motor changed. 302.5C. Drive…

CAT 302.5 recently had...

CAT 302.5 recently had a drive motor changed.

Mechanic's Assistant: What is the complete model and serial number of your machine?

302.5C

Mechanic's Assistant: Are you fixing this yourself? What have you tried so far?

Drive motor was replaced but now it sounds like heavy cavitation within the hydraulic system. Tried to flush air out but problem continues

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Answered in 15 minutes by:
2/24/2021
Mechanic: Dan, Technician replied 1 year ago
Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 15,100
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
Verified
Hi my name is***** will be glad to try to help you out with this. If the drive motor was replaced but you are still experiencing travel problems, try to deadhead your drive motor function by pinning your track and sprocket with a bucket pin or equivalent to prevent travel while operating other functions on the machine in hopes to force out any remaining air. You also want to be careful that there is no traces of a component failure existing or contamination within your hydraulic system and valves from a previous failure.check inside your hydraulic filter and suction screen for what looks like glitter or fine metal in the oil and filter. If found the complete hydraulic system is going to need to be cleaned out. If there is still pump noise and cavitation you will want to verify whether or not the pump is actually producing metal in the system and failing.usually once you start hearing that pump cavitation noise it is already too late and the damage is done to the pumps and components of the system. If all of this is clean, you want to have your pressures and flows tested to confirm they are within OEM specifications for your model and serial number machines service book. One other pointer that I want to mention about drive motor problems is that 9 times out of 10 rotary manifold SEALS or in other terms swivel seals bypassing internally will cause a loss of hydraulic flow and pressure to your drive motors ultimately causing drive motor problems. Reply back with the results of these checks if any further help is needed. It's a pleasure to help anyway I can.
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Customer reply replied 1 year ago
Hi Dan
Thanks for the reply.
Changed out the hydraulic filter and inspected but all was clear. Put another one in after topping up the oil.
What’s strange is operation of the blade and slew ring doesn’t create the noise. It seems to be mainly coming from the dipper cylinder and bucket cylinder. When I looked at the oil returning to the tank it seems to be foaming. A strong vibration can be felt on the cylinder rods and also back on the main valve body. Thought the air would self bleed but this is still the case after 2-3 hours of cycling the whole system.
Do you think it’s worth a full system flush?
Also with with the rotary manifold is there an easy way to diagnose?
Thanks again
Mechanic: Dan, Technician replied 1 year ago
Thank you for the updated information. If that type of problem is only isolated to those functions I would take a closer look at a possible problem within the cylinder and cylinder seals bypassing internally or within the main control valve spools for those functions. Take a look at the control valve spools for any trash or debris as well as any scoring or damage on the machined surfaces. You will also want to inspect the relief valve cartridges for those functions as well for any damaged o-rings or other trash and debris lodged within the relief cartridges.
Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 15,100
Experience: 17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
Verified
Dan and 87 other Construction and Road Equipment Specialists are ready to help you
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Customer reply replied 1 year ago
Thanks Dan I will have a look at that
Mechanic: Dan, Technician replied 1 year ago

You are very welcome.

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