JD 2955 hydraulic preesure

[FY-2955]

Can any good JD mechanic figure out why my 2955 has so much hydraulic pressure that it explodes the filter canister,[its not a spin on] ,new bypass valve ,checked pressure valve ,sump filter is clean....driving me crazy ,cant figure out the problem.

 

[Harry in Ky]

I don't qualify as a John Deere mechanic regardless how much I might think I know about the system. Having seen similar (if not your personal) posts here and probably elsewhere as well concerning this problem, I haven't read all of them nor many of the replies you received. I'm sort of coming in "cold" here so maybe you could explain again what's going on? Maybe any history on the problem, what if anything you think might have brought it on, like recent work done, changes, replacement, or incidents with the system? That sort of thing.

What exactly breaks here? A gasket failure or the cover casting itself? What have you done so far in the way of trouble shooting and testing? Not necessarily parts replaced, but what have you done to isolate the source of the excess pressure reaching where it apparently shouldn't be?

 

[FY-2955]

Canister blows apart ,no changes were made to bring this on ,halfway through spreading a load of manure and it blew apart.Have blown a new cover also after checking by-pass valves etc.

 

[Harry in Ky]

Check your PM inbox

 

[Tx Jim]

I find it difficult to comprehend that 165 psi trans pump pressure is breaking a metal filter housing! I think pressure from front hyd pump must be finding it's way to hyd filter circuit. Which hyd filter cover(cast or pressed steel)? Has hyd stand-by pressure been checked recently? Does tractor hyd system have extra hyd control valves attached to system? If so what type?

 

[FY-2955]

Yes, there used to be a loader on the tractor, so there is a return from the loader spool valves into the ported cover of the hydraulic filter housing , which has been the case since the tractor was new . and the cover is cast aluminum,,, shouldn’t the filter bypass valve alleviate pressure ?

 

[Tx Jim]

Has loader control valve been checked to be sure it's operating correctly for closed-center hyd system. If loader valve is still attached to hyd system you can disconnect FEL control valve return hose from hyd filter cover & install plug in filter cover. Now aim open return hose in tractor hyd filler hole & start engine & with FEL control valve levers in neutral no oil should exit open return oil hose. Which hyd filter cover part # T31170 or L55982 are you using??

 

[FY-2955]

Not sure of the part number but it’s a cast aluminum cover, which I have broken two of

 

[Jim.ME]

Yes, there used to be a loader on the tractor, so there is a return from the loader spool valves into the ported cover of the hydraulic filter housing , which has been the case since the tractor was new . and the cover is cast aluminum,,, shouldn’t the filter bypass valve alleviate pressure ?

I don't have a TM for the 2955 and am looking at a 2030 TM, which I think is similar. Look at the schematic in your technical manual. My manual shows the bypass valve normally would open to relive pressure above 50 psi from the transmission pump if the filter was restricted, so yes it would seem it should dump to the reservoir before exploding the cover. It also shows a surge relief valve and an inlet check valve in the line from the filter to the inlet of the main pump. The check valve is supposed to stop bleed back from the main pump when the transmission pump is not working. The surge relief is to take care of spikes over 100 - 140 psi in the main pump inlet line.

Do the test Tx Jim recommended for the loader valve. Another option would be, If the loader is no longer on the tractor, unhook and plug off the loader valve supply and return lines which would totally remove that valve as an issue. If it still blows the cannister, the problem is internal to the tractor.

Does your manure spreader use the remote hydraulics? If so for what functions? Has it blown using other, or no, implements?

 

[WTW]

The only way high pressure can build to blow the filter can is if the valve that controls this pressure is stuck closed or stuck causing restriction. The filter bypass valve does not control this pressure it is a "Bypass" valve to bypass the filter it has nothing to do with controlling the pressure in the filter can. The valve that control filter / system pressure is the pressure regulating valve located in the transmission top / shift cover, This valve needs to be removed and inspected.

 

[FY-2955]

OK I understand and agree totally with your answer , I removed the pressure valve that is on the side of the transmission the valve with the spring and the shims ,,everything appears clean and operating. Is there another valve controlling pressure somewhere?

 

[buickanddeere]

Something maybe in the transmission , restricting the flow of oil towards the the front pump .

 

[WTW]

From this control valve oil is routed to main hydraulic pump inlet and if not needed at pump, oil flows out of pump inlet housing to cooler then back to rear of tractor for lubrication. Somewhere in this circuit there is a restriction?? Has there been any work done on this tractor recently that could of effected plumbing?

 

[FY-2955]

No no recent work ,still very puzzled and taking it to JD for repair