03-11-2015 01:14 AM
I too have been having a similar issue with the hydraulic pump and it was taken to the rebuild shop, don't know what the issue was. We just replaced it with another one https://www.nriparts.com/hydraulic/hydraulic-pumps/komatsu/07436-72202-engine-steering-oil-gear-hydr... of KOMATSU brand and it is working good. I would like to know if any one of you have resolved the issue. If then, please post it up.
01-05-2015 04:56 PM
Hello all, Just joined the forum and have read everything on this topic I could find. We just purchesed a 330cl with hydraulic issues as decribed in this post, makes noise and has a lot of air in the oil after a few minutes of running. I'm just gathering as much info on the subject as I can before tearing into it. I dont see if any of you have resolved the problem and if you have please post it up.
12-18-2011 08:48 AM
12-14-2011 10:05 AM
I have been having a similar problem and its seems to have started like this... Firstly the machine had an oil leak from the seal on the inside of the pump near the coupling so the guys took of the pump changed the seal. However before this happen the operator experience some times a jerking movement in the swing as well as the stick and bucket. At this stage there was no wining noise though. Further to this the stick had a drift and would get very hard when you trying and retract it at some stage, Anyway change the seal, filters and oil and purged the system to find a noise from the pump as well as as bubbles in the site glass. Ok after extensive checks we found some debris in one of the valves for the stick so ordered the new seals and ready to fit we removed the stick cylinder only to find major damage to piston and bore. Next option new cylinder reflushed the system, clean valve banks machine now had normal operation but still the bubbles and whining noise. About to give up as can seem to figure out what is wrong. Sorry forgot to add removed pump and took it for testing and no problems at all. I have sis on my laptop and cat et so any tips on what to check or do next would be very helpfull.
02-22-2011 01:41 PM
I have done a little more digging. It looks like CAT has an update or service info that states there may be an issue with the suction line from the tank to the fan motor that is driven off the front timing cover. This hose can cause a restriction and the pump will suck air in thru the front seal. CAT also recommends to change the front seal as well on this fan pump.
This air in the system can cause some noise in your pump. We are in the midst of making this change to try to make our pump stop whinning.
02-21-2011 05:10 PM
Have you have any resolution to this issue?
We have also experienced a similar situation. Found that one pump would drop off in pressure to less that 500 psi, while the top one would hold at full relief pressure. very strange. We eliminated the system by running the pumps thru a flow tester back to tank.
Pumps were replaced and old one is going back to the rebuild shop to find out what happened. Just curious if you had resolved your issue?
01-27-2011 09:04 PM
That is wierd, usually the main relief will take care of that. There are also NFC reliefs at each end of the valve body that controls the two pumps. Possilby if one of them was sticking would cuase it. Did you calibrate the powershift pressure when the new pump was installed, that may make a difference.
01-26-2011 09:42 PM