My D31A-17 dozer (hydrashift) was working fine up until a week ago. I started to hear a change in the sound coming from the machine. It only occurred at operating temp- a whine like a pump being starved for oil. It seemed to be coming from just behind the motor ie hydraulic pump. I changed hydraulic filter and oil. Whining did not go away but did not get any worse. I had also checked oil level in transmission. It was fine. Approx 3 days ago, started dozer and the whine started immediately. Oil levels still good. Used machine for approx 30 minutes. Forward or reverse motion quickly became non-existent. Hydraulics still work fine, engine sounds good. Machine refuses to move. This week I will attempt to check strainer for blockage, and output pressure from transmission pump. Any other ideas would be greatly appreciated. Supply of pump parts if needed? In the past, Komatsu has always wanted WAY TOO MUCH for their parts.
Did you ever solve this. Mine is doing the exact same thing
My problem was plugged strainer on the transmission. 1. Drain oil from transmission 2. Remove strainer plate on front lower corner of trans. Clean strainer. I also removed pump housing on front of trans. Everything looked good. 3. Reinstalled strainer, sleeve, pump housing using new o-rings and rtv sealant as required. Everything works great. Good luck.
Thanks for the reply. I have tried that and it did work briefly. In fact i didit three times. It has got to be something there but i can not find it. I really appreciate your input. Didnt get back sooner because email was in spam.
Thanks for the reply. I have tried that and it did work briefly. In fact i didit three times. It has got to be something there but i can not find it. I really appreciate your input. Didnt get back sooner because email was in spam.
HI, my first post here. my boss has a D31A with about the same problem. I cleaned the strainer but the problem is still the same. Putting it in forward or reverse causes a bog down condition which will kill the engine if we don't go to neutral. I am thinking it could be the hydrostatic drive went out. Anyone have any ideas. Thanks Rick
rick6003.......D31A is not hydrostatic. Malcolm2......I had a very similar problem with a Cat D3B. Try running it without the suction screen. Let me know if that works. Steve. www.sadygerts.com
If the trans pump looks good and the strainer clean, then you probably have suction leak to trans pump. Have you checked the trans pressure. Pumps make an awful noise when air goes through, cavitation.
thanks guys, I feel pretty dumb. I was messing around with it today and tried the hand brake. It was in the up position. It looks like its off at the up position. This seemed to fix the problem on the drives. Makes sense now that I think about it. New problem seems to be bad fuel, clogged filters or "?" Going to change the fuel filter tomorrow and will try to find out what that big canister beside it is. If its a separator it probably needs a cleaning also. Got a few minutes scarfing off some ground with some nice power till engine started sounding like it was only hitting on 2 cylinders. Great forum by the way.
I forgot to add. Its a D31a-17 model. It has a power shift like the old TD-29 my dad built road with for many years. I thought they called that Hydro static drive. Thanks again