Hello this is my first post so forgive me if somethings not right I have a case 1835c that has been giving me some problems it all started 2years ago I used it all summer without any issues but it sat outside for a night in the cold and wouldn’t move so I got it back home and check the charge pressure and was 260 psi so I figured it had to be the rotating groups pulled the pump apart and everything looked perfect no scoring on any of the brass surfaces so I reassemble did a filter and fluid change and everything worked perfectly again then last summer same deal used it just about everyday as soon as it got cold same thing checked charge pressure still good so back apart it came to find nothing same as last time everything looks perfect it’s like the bypass valves are open I disconnect the drive hoses and caped the pump and it’s definitely in the pump I can work the controls and not stall the engine I talked to a guy that was pretty confident it was the charge pump so I replaced it and it’s a little better but still not fixed any ideas would be greatly appreciated
Here’s the pump tag if it helps
Have you looked in the chain cases? If the 1835c is like the 1845c, they tend to get water in the chain cases. Then you leave them outside overnight in the cold and the water in the chain case can freeze and lock up the chains and axles. Worth a quick check if you haven't already.
I’m 98% sure its in the pump because the oil comes out of the tank thru the loader pump form there to the main control valve and I know it’s working properly because I have all the loader functions and from there to the filter then to the drive pumps I capped all 4 of the drive ports to the motors on the pump and I get very little drop in rpm when I work the F/R controls Thank you I really appreciate your help I’m open to any more ideas you or anyone else might have
If there is water in the chain cases has nothing to do with the hydraulics but will certainly stop a machine dead in its tracks. A hydrostatic transmission is set up not to stall unless you really overload it, a sort of load sensing. What you described sounds exactly like frozen chain cases. Always look for the simplest answer first. I think if was the pump would act up all the time and lose power when the oil got hotter.
It’s been 60ish degrees for the last few weeks and the only hoses to the tandem pump are the feed from loader valve and return to the tank so the chain boxes are completely taken out of the circuit by capping the drive ports (all 4 both sides forward and reverse) it is not letting fluid flow anywhere and is dead heading the pump and should definitely kill the engine on a property functioning unit
Have you checked flow and pressure from the pumps? Pumps don't just wear out from sitting but if the pumps are bad they should be worse when hot. What oil is in the machine? Perhaps something in the pump sticks when it's cold or the oil is the wrong viscosity.
Owners manual calls for 10w-30 with HTO additive at 20:1 ratio and that what I’ve always ran charge pressure is 240psi (I made a typo on my original post it’s 240 not 260)at full throttle hot or cold and the spec is 250psi max at full throttle with hot oil the main pump pressure should be around 3045psi and I’m getting nothing but slight moment on the gauge at all 4 test ports I realize that pumps don’t just wear out but there’s no way all 4 check valves failed at the same time
The chain boxes do not tie into the hydraulics. They are "wells" that hold oil to self lubricate the chains as the wheels turn. One on the left and one on the right side of the cab with access ports (See attached pic. You can see the passenger side covers on the left side of the pic by the wheels) If water gets into them they freeze. Dirt also can contaminate the oil. The 1845c have an issue with the 4 covers (2 on each side) leaking. Many put RTV sealant in them to reduce the possibility of contamination. You mentioned this happens when it gets cold. If it gets below freezing that may be your problem. A machine can be stopped dead in its tracks if the water freezes. If it has been in the 60s this obviously may not meee your problem. I just bought my 2001 1845c a few months ago. The prior owner said the "full service" had just been done.....wrong! The chain cases were filthy! I emptied them and washed and flushed them with diesel fuel. They are sparkling clean now lol
I'm not an expert on these so take my advice with a grain of salt but it sounds like your servos aren't stroking for some reason. Right in front of the control lever on top of each pump there should be a small allen head plug. Those are ports to test for pressure and flow to the servo housings (sideways things at each end). Put a gauge on them and see if you get anything. If you have pressure there (should be charge pressure I think) then take the plug out of the endcap of the servo housing and see if you're getting pressure on the servo itself when you move the controls. Obviously use cation when doing all this.
on the bottom of the hydraulic tank there is a drain plug, lossen it up just enough to see what starts dripping out. oil will float on water so if there is any water in there it will come out first. doesn't take much water to lock those hydraulics up. I had the same problem this winter with my 1845. I drained probably 1/2 cup out of mine the first time. 2nd time just tea spoon. its okay now. it only happened when it got cold. good luck