51 CA hydros won’t lower???

My 1951 CA has always worked flawlessly in the hydro dept since I’ve had it from my grandpa. The lift arm hydros, cylinders were rebuilt two years ago just because they leaked bad and other than some leaky axle seals never had an issue… tractor has a snap coupler converted blade for snow and driveway

I was plowing tonight and noticed the lowering position when i threw the lever was getting lower to the floor board to drop the blade, I was able to finish but by the time I parked it the cylinders will not lower…. Even with the heavy blade hanging they won’t go down, I tried changing pump settings and no luck… I will check it in the morning and see if they have dropped any

Where do I start to troubleshoot? Traction boost? Linkage?? Pump and hydros have worked flawlessly until today, never had an issue lifts and lowers great, I checked the linkage and nothing seems out of whack, I don’t know a lot about hydraulics in general and the manual is not great for troubleshooting this but I rebuilt the whole engine on this tractor and am mechanically inclined

I wouldn’t think it’s the pump itself as it lifts and works fine and the drop on these things is basically the implement weight? any guidance??? Like I said I have never had a problem until today with it . I did drain the trans/hydros while it was warm and I am gonna put new in tomorrow maybe flushing some crap out?

Edited by bigredneck61088 - 17 Jan 2022 at 12:24am

I went out today and they didn’t drift down still stuck up… with the converted snap coupler blade hanging. None of the linkage looked out of whack and nothing froze that I could see. It all externally looks as it did when it was working

Didn’t have enough time to do anything else, used the quad to do the drive today

I have it set in the hold mode, should I try switching to the other modes to see if it works that way?

Edited by bigredneck61088 - 17 Jan 2022 at 5:40pm

I don’t know a lot about the traction boost, just because it’s always worked, I’ll check it for ice tomorrow wasn’t bad when I parked it but I didn’t look close, but how do I lock it out with the knob???

Ran it a bunch today and monkeyed with it…. I let it run a while to warm up the case, checked traction boost and un pinned it working it manually with pliers and it tried to raise. All linkages and all seem to be set right. I un pinned the plates and they weren’t froze and separated.

After a while running I could bump it up and it would creep down a few inches and slow, hydros work real fast up now. I pulled it into the heated garage and gonna let it sit overnight, I was able to monkey it and get it to drop after shutting it off but I was bumping the lever back and forth and I was in the almost up position… but the lever is real funky like something is stuck or froze inside, we will see what a night of warmth does.

After it froze up I drained and I refilled all the trans fluid today before running it so if it did have water it should have flushed some… could something be froze up in there? I was running standard universal trans fluid with a little Lucas hydro fix to slow the axle seal leaks and everything worked fine prior to the other day

Should I plan on taking apart the hold valve? Is that something that could have an issue…. Pump has good up pressure so I’m not sure what to get into next

Edited by bigredneck61088 - 19 Jan 2022 at 12:05am

Glad you got it fixed.