Hello all - recently bought a B1700 HSD project tractor to try to resurect. It has sat for about 13 years. We got it running but now we are at the point where the original owner parked it - he said it just quit moving one day while working with it. He said the Hydro was bad. Well, we had a few things to get repaired before we started it. The lines from the filter housing were crushed and the mounting tab broken off. Got those repaired, filled with new Kubota fluid and filter. Checked the suction screen. At this point, I hooked up a pressure gauge to the charge pump port and have 0 charge pressure. Power steering works. lift arms are all the way up and don't seem to want to go down. WSM looks like the hydraulic / power steering should be pushing fluid to the charge pump. I would think there would be some pressure even if the charge pump was bad. Anyone have any thoughts on this situation? Thanks - Dan
New member B1700 HSD Hydro problems
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TheOldHokie
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I picked up a cheap set of hydraulic gauges off ebay. It came with several adaptors and 3 gauges and test hoses. The lowest gauge was still too high pressure to check for a 50 psi charge pressure so I used the adaptors and managed to connect a 0-100 psi gauge to the test hose. The test point I used is the 9/16" sae fitting test port in the bottom of the hydrostat as shown in the service manual.
TheOldHokie
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Hydrostatic transmissions are not my strongest subject but looking at the WSM the output from the charge pump is combined with the output from the PS. The charge pump relief regulates that pressure before it is introduced to the transmission.
I think I would look for pressure any place upstream of the relief. If it's stuck open you are not going to get any charge pressure. Be careful - deadheading that flow can generate really high pressures that could damage things like the oil cooler. Use a setup like shown for testing main pump pressure. And don't let it go higher than charge pressure.
I was looking at the WSM on my phone which is difficult and I could not locate the pressure testing ptocedure for the HST. The hydraulic circuit diagram shoe's three ports for charge, forward, and reverse circuits. I assume those are test ports for the individual circuits and you had the gauge connected to the charge test port. I will have another look when I get to a desktop.
Dan
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It looks like anywhere in the cooler loop would basically be at charge pressure. I need to get a couple fittings to make a connection into that loop - I need a T with a couple 3/8" hose barbs. It will be a couple days before I get to somewhere I can pick them up.
TheOldHokie
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A tee by itself does you no good. You already know that's going to be zero pressure. You need a way to partially restrict flow downstream of the tee - e.g. a throttle valve. Read the WSM description of pressure testing the main pump at the hydraulic outlet block for details on that procedure.
Dan
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North Idaho Wolfman
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As NIW mention ed, make certain the input shaft to the hydrostatic transmission is turning when trying to move the tractor.
If testing charge pressure you should be doing so at the P3 port at the bottom of the HST. It is the middle port and is either a SAE 4 or 6 fitting. You could conceivably test in the cooler loop but the most accurate place is P3. I would check charge pressure at idle and full throttle in neutral and while trying to travel forward and reverse.
If testing charge pressure you should be doing so at the P3 port at the bottom of the HST. It is the middle port and is either a SAE 4 or 6 fitting. You could conceivably test in the cooler loop but the most accurate place is P3. I would check charge pressure at idle and full throttle in neutral and while trying to travel forward and reverse.
TheOldHokie
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I believe he has already tested charge pressure at P3 and it is zero. The question now is why.
Dont know the state of the charge pump but PS is working so where is that contribution to charge flow/pressure going?
Dan
I would ask the OP if he has checked charge pressure at P3 as I never assume anyone has checked anything at the correct locations. Also what size gauge is he using as spec is only 43-71 psi so a 100-200 lb. gauge is what he should be using. If using a large gauge, say 3-5k it may not even register.
If there is still no pressure at P3 I would say that either the flow is blocked in the cooler/circuit or possibly the charge relief is stuck open. If everything is well there then it could be excessive internal leakage at on of the rotating groups.
TheOldHokie
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Most of that was covered in the OPs original post. He seemed to have the correct port and proper gauge.
At that point I suggested the charge relief might be the problem which is why he is proceeding to check for pressure upstream of that point.
Dan
Yes I have confirmed that the shaft is rotating. However the back ball coupler is not visible inside the frame, so I can't really say that end of the shaft is properly coupled to the input shaft of the hydro. It turns true so I am assuming for the present that it is OK. Some play but no more at the back of the shaft than at the front. Yes I used a 0-100 gauge (had to adapt the gauge since the set did not have one that would read low enough) connected to the center port on the bottom of the hydro. I did not try at full throttle but was at a high idle when checking. The needle never budged. I just drained the new fluid out to fix a small drip in one of my line repairs and checked the suction screen. It had a few small cuttings but was generally clear. I'll get the drip fixed and refill it today. I also checked the charge bypass while I had it drained to make sure the spring isn't broken or the valve stuck. I did not find any shimms under spring and the cone looks good. Everything looks good and moves freely so I put it all back together. The filter was full of oil when I unscrewed it.
Dan
Dan
Ok - I scrounged through my fittings and came up with a setup that I could insert into the line with a 1/4" ball valve that could introduce a restriction.
When I started the tractor, the pressure went up to about 56 psi right off.
I started to close the valve slightly and it smoothly increased to about 77 psi. I did not leave the restriction in long. You can see the lever of the ball valve just slightly closed. This is between the hydraulic cooler and the filter. I'll move it to the other side of the filter next chance I have to work on it. Out of time for today.
When I started the tractor, the pressure went up to about 56 psi right off.
I started to close the valve slightly and it smoothly increased to about 77 psi. I did not leave the restriction in long. You can see the lever of the ball valve just slightly closed. This is between the hydraulic cooler and the filter. I'll move it to the other side of the filter next chance I have to work on it. Out of time for today.
TheOldHokie
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Well you have flow. I was hoping it was going to be an easy fix with that relief but you checked that already. . Fingers crossed the filter is the culprit.
Dan
Filter is a new Kubota filter so I'm not too worried about it being bad. I'll get the gauge moved to the other side of the filter in the next couple of days as time permits. I do have an STP sub filter I can put on if it looks like the new filter got plugged up. I picked up another gauge so that I can monitor P3 at the same time once I get it hooked up.
TheOldHokie
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For your sake I would like to think thats going to find the problem but I rather doubt it. I think major surgery is going to be needed.
As I said initially HST theory and service is not my strobg suit so I may be way off base.
Dan
Waiting on an adaptor to check the forward and reverse high pressures but have my doubts that there I find anything good. However I have another question on this tractor. I can roll it in neutral as lomg as I have the front wheels on dollies. The front wheels will not turn - they just slid when I winched it off the trailer. When I jack the front up, they will turn through the differential, if I turn one forward the other goes backwards - no effort to turn them. This tractor has the bi speed turn. I tried both positions on the lever with no difference. It seems the front drive shaft wont turn. I looked at trying to drop the shaft but it looks like a major operation to get it loose. WSM is not much help. Any thoughts on this? Could this be related to my transmission problems? It is in 2WD position. Putting it in 4WD position locks all 4 wheels up just like the front wheels.
Do you have charge pressure at the P3 port now? There should be no reason you would not if you have pressure before the filter. The filter will not cause that much pressure drop and if the path was completely blocked pressure before the filter would rise until most likely a hose comes apart.
As far as the mechanical section, as long as the hi/lo range is in neutral there should be no connection to the HST output shaft. If the front wheel drive selector is in 2wd there should be no connection to the mechanical section of the transmission.
Do the rear wheels turn when towed in neutral? They should not turn or turn only a very small amount if not in neutral. I assume that when trying to move the tractor there is no change in tone from the engine or in the transmission area.
I also forgot to ask does the rear PTO work?
As far as the mechanical section, as long as the hi/lo range is in neutral there should be no connection to the HST output shaft. If the front wheel drive selector is in 2wd there should be no connection to the mechanical section of the transmission.
Do the rear wheels turn when towed in neutral? They should not turn or turn only a very small amount if not in neutral. I assume that when trying to move the tractor there is no change in tone from the engine or in the transmission area.
I also forgot to ask does the rear PTO work?
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I have not gone back to check P3 yet - haven't had any shop time for the last few days. That is next on my list. As far as the sound of things - when I try the hydro in gear I get no difference in the engine sound and no difference in the sound at the transmission. The rear wheels do lock up in 4WD mode but I have not checked with it in gear and not in 4WD lately. I'll check. Both pto shafts work. I had to order an adapter for my gauge set to connect to the High pressure ports - it should be here in a couple days and I'll get back on this when it shows up. By the way, if anyone needs hydraulic adapters, Surplus Center in Nebraska has a very good selection at very good prices The SAE #6 to SAE #8 I need is less than $3 from them.