This is the exact pressure I am getting from the Forward/Reverse and Lubrication circuit. I think my next step is to figure out the thread going into the shuttle valve and test the pressure coming out of the priority valve. I also removed the added shims off the plungers I showed a few posts back and there was 0 change in preasure.
L4150DT Hydraulic Shuttle "slipping"
- Thread starter gpsmatty
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rbargeron
Elite Member
The lever by your left foot is for PTO speeds - low-neutral-high.
The L4150 had 2-speed pto - but its newer version L5450 had only low and neutral. Both my L5450's have been converted to have both low and high speeds.
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Testing the pressure out of the priority valve to the shuttle shift blew the hose and my gauge, so I guess that means the pressure is good out of the priority valve. Could there be a leak inside the transmission bleeding off pressure for the clutch packs? I located a used shuttle shift assembly I'm tempted to get and try.
rbargeron
Elite Member
Looking at Kubota's parts lists I don't see the hydraulic shuttle clutch pack listed as a kit any more. A used hydraulic shuttle? Is there a pic of it showing if its just the clutch packs or includes the shaft with oil passages? The L4150 was also available with a gear-type shuttle - many parts are different.
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I meant a used shuttle control valve.
I've got good pressure coming out of the priority valve, but only getting about 50 PSI when I test the Forward/lubrication/reverse circuits on the shuttle control valve. That either tells me there's some kind of a blockage or something in the valve, or that there's an internal leak? I am prepared to split the case again and replace all the shuttle clutches and steels but want to make sure the hydraulic pressure is good first so I don't end up in the same position once I replace them.
My $.02 if you have to buy used parts the 3750 and 4150 use the same parts on most of the transmission/ and all of the hydraulic shuttle components. Maybe try a search of the 3750 dt hydraulic shuttle clutch/ trans slipping? It's a great tractor when you get it figured out.
Just a quick recap on pressure testing from the Shuttle control valve. I'm getting about 43 PSI from the forward/neutral/lubrication circuits, I tested pressure out of the priority valve with my 500 psi oil test setup spun the needle around 3 times, and blew the hose. That tells me there's good pressure out of the priority valve. My other hunch was some kind of an internal hydraulic leak within the transmission bleeding off the pressure. Today my replacement oil pressure testing gauge/hose came and this time I tested pressure out of the Forward hydraulic line output and the pressure was exactly the same, taking an internal leak out of the equation
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I've stared out the diagram in the workshop manual till it looked like spaghetti, but there is a pressure relief valve that cuts the lubrication pressure down to 42.7 PSI
at this point, it seems like all the positions are pushing open that relief valve. I'm thinking maybe there's a blockage in one of the orfices or something that is routing all the oil through the pressure relief valve?
It's time to take it apart and see what I can find, if it doesn't fix it, I'll order the one on eBay.
.I've stared out the diagram in the workshop manual till it looked like spaghetti, but there is a pressure relief valve that cuts the lubrication pressure down to 42.7 PSI
at this point, it seems like all the positions are pushing open that relief valve. I'm thinking maybe there's a blockage in one of the orfices or something that is routing all the oil through the pressure relief valve?
It's time to take it apart and see what I can find, if it doesn't fix it, I'll order the one on eBay.
I pulled it apart and checked everything out, but couldn't find anything inside that didn't look right when I compared it to diagrams. Considering it had twice as many shims as it should have on one plunger, and lock washers as shims on the other, I decided to take a second look. Went through the WSM and went over all the diagrams and I finally noticed something:
With the shuttle control at the same orientation as the diagram, 020, the selector piece is clocked wrong on my pump.
With the shuttle control at the same orientation as the diagram, 020, the selector piece is clocked wrong on my pump.