Have a case 430 that has a hydraulic issue on the left side. drive wheels on the left are getting weaker / slower. It's not that noticeable yet on start up when oil is cold but when things heat up it gets worse. It's either the pump or the motor but rather than blindly replacing I was hoping to be able to determine, or at least come up with a somewhat educated guess, what is the problem. Is there a way that I can determine which is the issue? If I understand the system correctly there are 2 pumps, one for the right, one for the left. At least that's what I was told and it appears thats true when looking at the pump (s), they appear to be a mirror image of each other mounted in line. Also it's a 2 speed skid steer it that makes a difference. Any advice would be appreciated. thanks.
Do you have pilot or mechanical controls? Before you condem a pump or motor, do some quick checks first. On machines with 2 speed, the 2speed spool spring in the motors breaks sometimes. This will give you low power on the side with the issue. If this is not the issue, cut open the hydraulic filter. It may contain brass (which would be parts of the pump or motor). In general, in a closed loop circuit, such as this, it is best to have both mating components repaired together. This is due to the fact that the oil/debris goes from the pump to motor, back to pump, and repeat. Generally, if a motor has failed it will overfill the chain drive case. (the shaft seal will blow out from excessive case drain flow) If you still want to find which component is faulty perform a charge pressure drop test. To do this, perform the following steps. Dissconnect the park brake solonoid. T in a gauge to read charge pressure (should be at least 360psi and you can T in at the 2speed/park brake valve) Rev the engine up to full throttle, and slowly engage the left pump. If the charge pressure drops more than 30psi, it indicates too much internal leakage in the pump/motor. To determine which has failed, cap off the lines to the motor at the motor. Repeat the test, if the charge pressure still drops, the pump is faulty, if the charge pressure remains ok, the motor is at fault.
Thanks for the reply, regarding the 2 speed spring. if the spring is broken, will the high speed still work? It appears the high speed seems to work normally, although as the machine warms up it seems to slow similarly to the regular speed symptoms. Will check out the filter, see what I find. regarding getting these components rebuilt, does it take a specialty hydraulic shop to do so? or are there aftermarket rebuilt units available? sorry for the many questions, trying to get the machine back on it's feet but replacing with new pump / motor approaches the cost where it gets questioinable whether it makes sense to fix or scrap it. At least that's what it seems to be so far with cost estimates I am getting.
Called in for pricing on new and it appears I was wrong about there being 2 pumps, it's only one. Motor is about $2200 and pump is pushing $4500. Wondering now if the pump or motor is shot will the contamination (metal etc) be contained to the one side or will it have been circulating through the other side as well. Don't think the machine is worth investing $9000 in to replace all and have something else go after that. Any idea how much getting them repaired would be?
oh and it's mechanical controls