B1550 Hydrostatic Trans whine.

alchemysa · Oct 7, 2006

Hi from Australia. I bought a B1550 HSD a couple of months ago and I'm just starting to put it to work. The engine is excellent (3000 hrs) but the hydrostatic trans is acting up. Sometimes it whines terribly in forward 'gear'. At times if I'm moving fast it will happily go for 100 yards then slow to a whining halt. At other times it won't move at all. It doesnt seem to matter if its in 4WD, 2WD, Hi or Low range. Playing with the revs usually gets me going again. It seems to be OK in reverse but I haven't gone too far or too fast in reverse to really test it. The trans dipstick says its full of oil but I'll be fully replacing the oil and the filter next weekend anyway. I've ordered a manual from the US that covers similar (but not the same) Kubota models, so i hope that will give me a few clues, but I'm not sure when it will arrive. I've already got a parts manual with great drawings but that doesn't really help much with problem solving. So I'm wondering if you guys have got any advice on how to improve the trans performance, even marginally. Are there any other filters or screens i should be checking? Or valve adjustments I can play with? I think I've also read on other threads that the position of the 3pt hitch lever might have some effect. (Or did they say the PTO speed lever?). Since I bought the tractor, a backhoe has been bolted onto the back, forcing the hitch lever into a full height position and requiring the PTO to be 'ON' most of the time. Is that something worth checking out? I have a Kubota dealer nearby so i can get any parts or tools but the tractor itself is currently 300ks away on an acre on which I'm building a shack. (As a last resort it's a long haul to get professional repairs). The tractor is still very usable as it is, but if I can't get it working perfectly I'd at least like to minimise any potential damage til I can get it to a pro. Thanks in advance for any advice. David

bird1968 · Oct 7, 2006

Flush the tranmission & check/clean the hydro screen.

If there lots of sign of metal shaving, there a good chance there may be something wrong in the transmision.

You could also use a magnet, into the drain plug opening, to see if you could catch some bigger metal shaving.

Do not wait to long.

Bird

ozzie tractor · Oct 17, 2006

sounds to me like an air leak on the inlet side of the charge pump which pressureises the hydrostatic trans. this will be on the front of the transmission where the input shaft comes in (inside the tunnel between your feet), there may be a small amount of oil on the pipes that come into the pump, pull the pipes out and check the orings, it wont leak much oil as its above the oil level and on the suction side. if the orings are ok, check back alnog the pipe and look for any oil at all and fix leak as required. i had a kubota F2560 do this a few years ago. the other posibility is the wrong trans oil is in the machine, which can lead to excessive aeration of the oil, which gives the same result. check those few things and see how u go

alchemysa · Oct 31, 2006

Thanks Bird1968 and Ozzie for the replies. I finally got a spare day to work on this problem. I replaced the oil, the oil filter, and cleaned the wire mesh screen,.. and what a difference! Previous to this it literally wouldn't climb over a brick. Often it just screamed and wouldn't move at all. Now when it hits an obstacle it's spinning the back wheels even with the weight of the backhoe on the back. The real key was removing and cleaning the wire mesh screen in the transmission suction line as illustrated in Bird1968's pic above. (part 070 in the pic attached). Mine was trapped behind a backhoe support bracket so I doubt that it had ever been cleaned. To get to it I had to remove the the battery, the battery tray, and the left hand wheel and mudguard. Then I was able to remove a big bolt and swing the bracket out of the way to get at the screen. The screen was absolutely clogged. I cleaned it pretty well with petrol, a wire brush and compressed air. (But I wish I'd just had a new one to replace it. Only $18, so I'll get one for next time). With a clean screen letting the oil get through, this is a different machine!.

On the RH side there's another identical mesh screen that filters the oil thats going to the loader, power steering, and 3pt lift. I wanted to remove this one too but, thanks to a monumentally stupid piece of engineering, the subframe of the genuine Kubota loader prevents this screen from being unscrewed. (I'll have to get a 9'' grinder onto it to take about 5mm of metal off the frame). But I think I came up with a good short term solution. I disconnected the rubber tube from the suction pipe to the power steering (part 050 in the pic attached), attached my own piece of rubber tube, and blew compressed air back into the pipe. I could soon hear this blowing freely through the wire screen.

I'm sure this problem of dirty mesh screens would be common to many Kubota's so I'd recommend you clean them every time you change the transmission oil.

rdsaustintx · Nov 1, 2006

Glad you got it figured out. Great feeling, eh?

Also encouraging that the HST suction could have been so restricted, but apparently no serious damage to the unit. Tough little critter.

RDnT

alchemysa · Nov 2, 2006

rdsaustintx said:
Glad you got it figured out. Great feeling, eh?

Also encouraging that the HST suction could have been so restricted, but apparently no serious damage to the unit. Tough little critter.

RDnT

I'm not totally sure no damage was done. It still, often, has an unpleasant whine but I'm told this is pretty normal. But at least now it's got plenty of grunt so I'm hoping that indicates theres no serious problems. I'd have to drive a 'perfect' one to feel the difference. I don't think I want to do that .. I might learn something I'd rather not know.