Pump Noise Komatsu PC200

Hello to all,

I recently purchased a 1990 Komatsu PC200.

It has about 2,000 hours on on a rebuilt pump.

Anytime the bucket, stick, tracks, etc are moved the pump makes a fairly loud sound like when the power steering on a car hits the stops. The prior owner said the pump had made that noise since he bought it slightly used many years ago. Both before and after the rebuild of the pump.
It has run fine for me int he time since I have had the machine.

Just wondering if anyone would know what causes this sound? I have run other excavators and not heard this kind of pump noise. It almost seems like maybe some air is in the pump somewhere and needs to be bled off?

Thank you.

Welcome to HEF HeavyT! :drinkup

That vintage is most likely a Dash 5 machine and has the open center load sensing system. I never knew why but they always make that noise, especially at low idle. You probably should pull the suction stainer out of the hydraulic tank and make sure it is not partially plugged.

Generally if the machine walks a straight line and doesn't overheat th noise is nothing to worry about. It probably needs to be tuned up and that would lessen the noise some. At high idle it's not very noticeable. You might also check the pump control computer for fault codes. It's pretty common also for the speed sensor to overheat which causes the computer to only give you about 75% performance.

I would agree with John C, whatever series of PC200 you own the -3 and -5 are very similar pumps and are pretty robust. I seem to recall 'that noise' on both series of machines. I think both pumps (front and rear) should have damper hoses coming off the high pressure outlets. Make sure the lines are in place and are properly mounted to reduce any resonance from the pump.

A tune-up would be recommended but you would have to employ someone who knows and understands the hydraulic system to get the best out of the machine and to confirm that the noise is not anything serious.

John is correct that if the strainers and filter is clean and you are using the right oil - 10W engine oil everything should be fine.

Pump Noise Komatsu PC200LC-5

Thank you both for the excellent comments!!

Yes....it is a -5 model.

The machine walks a straight line, and it seems to have plenty of power. There is no overheating.

The prior owner bought if originally from overseas. It is a grey market machine.

We will pull the suction strainer from the hydraulic tank to check it, and also check the damper hoses.

We have been running AW-46 hydraulic fluid....assuming that is similar to 10w oil and is ok?

If everything is ok after we check it...then we will just run it as is.

One other question..... if we are not smooth with the controls, the the stick or tracks will start to chatter or shake. When this happens we just stop what we're doing give the machine a second or two then try to smoothly resume what we were doing.....does that mean anything to anyone?

Thank you.

The AW-46 oil will work fine in this machine. The jerky controls could be another issue. Usually it means the jet sensors are not set properly and the pumps are partially on stroke all the time. That also might be some of the noise you hear. You can probably expect to pay around $750 to $1,000 to get the hydraulic system adjusted. The system likely was not adjusted when the new pump was installed.

You are in an area that doesn't get hot very much so it probably isn't enough to show on the engine coolant temperature gauge. You might see it in the next few days when the weather is expected to get hot.

Good Luck!

Very good replies guys! Also when in doubt on a pump, do a case drain test.

Unfortunately a case drain test will not do any good on these types of pumps. The cases are flooded with oil directly from the reservoir and held under pressure by the residual air pressure on top of the oil caused when the level in the tank goes up and down from movement of the implements. Older systems had air compressors installed with pressure regulators holding at least 15 PSI on the reservoir all the time.

When we first got into them we even had problems reading them out with a flow meter. We didn't know how to cheat the load sensing to get maximum output from the pump. Even today most hydraulic shops don't have the ability to set these pumps up properly.

John C. said:

... even today most hydraulic shops don't have the ability to set these pumps up properly.

Click to expand...

Your dealer would probably have the ability to bench test the pump after overhaul but as John already mentioned the best place to fine tune the pump is on the machine when it is matched to the main control valves and you know how much HP the engine has available.

I would agree with John (again ) that the pump is overproducing flow when you first get going. The few hundred bucks it would take to set up the machine properly could be recovered in a few months with the fuel savings or additional production that could be recovered. As mentioned before you should really hire someone that knows the machine systems because the set up requires specialist knowledge.

Pump Noise Komatsu PC200LC-5

Wow...the wealth of knowledge on this board is impressive.

Sounds like a pump tune up will go a long ways toward correcting the problem.

Thank you all!!! :notworthy