JD 2550 pump question

[MMagis]

Pretty sure my hydraulic issues have been narrowed down to a failing main pump (JD 2550). My initial assumption was to just buy a new pump, but I see John Deere offers a rebuild kit. Are there any opinions whether this is a route worth considering? It would save me some money, but I don't know enough about hydraulic pumps to know whether it would be worth the savings, or if I should just replace the pump since we're taking it out anyways. Thanks

 

[J_J]

At least do a flow and pressure test on the pump at the dealer.

 

[MMagis]

It has been pressure tested (not sure about flow).

 

[kennyd]

Just to be clear, are you talking about a 60s or 70s era utility tractor, or the modern era compact utility tractor sold just a few years ago?

 

[MMagis]

In between I guess. It's an '85 model.

TractorData.com John Deere 2550 tractor information

 

[Tx Jim]

MMagis
More diagnostics is required before frt pump replacement is deemed necessary as many frt(main) hyd pumps have been repaired/replaced to determine that this pump wasn't the problem!!!!!!!!. There are many things such as low & high pressure internal hyd leaks that can give the same symptoms as a failed frt hyd pump. Does your tractor have the options of hyd ind pto &/or hyd hi-lo or reverser. The supply tubes for each hyd function I asked about have a long/long history of failure causing hyd problems. Has hyd's been tested with hyd pto both on & off and with hyd hi-lo in both speeds????? Is tractor equipped with a FEL & if so what type valve controls FEL? Long story/short story no many technicians of this day & age know how to correctly diagnose a JD closed center hyd system of the early 60'-early 90's.

 

[J_J]

Hydraulics:
Type: closed center
Pressure: 2300 psi [158.6 bar]
Rear valves: 1 or 2
Pump flow: 13 gpm [49.2 lpm]


Did you see the 2300 relief pressure when you did the test.

Check your flow in a bucket using the 10 second rule. 13 GPM = 1.3 gal in 10 sec.

 

[DLTTrekkers]

Run all tests BEFORE stripping !

 

[MMagis]

It’s currently at the neighbors, and I wasn’t there when they checked it out so I can’t say for sure what all was tested. I’m guessing it wasn’t everything listed and more tests need to be done. I do know the pressure was sporadic, it may read good when the RPMs are increased but when decreased the pressure would go away and may or may not return. It does have Hi-Lo and independent PTO. It also has an FEL, independent valve, not off the remote (not sure if that answered the question?).

 

[Tx Jim]

Test FEL control valve to see if it's reverted to open center valve by aiming open hose in bucket or hyd filler hole with both control levers in neutral no oil should exit hose when engine is running. Also look in hyd filler hole for spraying oil when 3 pt is raised and engine is running which would indicate blown rockshaft control valve seals. Test hyd operation with both speeds of hi-lo & pto on/off and report back.

 

[MMagis]

Will do.
I have looked for spraying oil in filler hole already, nothing there.

 

[MMagis]

Checked a few things over lunch:
Hi-Lo-no change on or off
PTO- no change on or off
FEL- no flow in neutral
The one thing I didn’t get to do was a flow test, I ran out of time.

We put a pressure gauge in one of the rear remotes again, the results may or may not mean anything concrete:
At idle the pressure was 0, as we increase the RPMs the pressure shot straight up to 2300 psi. Decreased RPMs and the pressure dropped back to nothing. This could be repeated over and over. There seems to be a knocking coming from the pump as the RPMs increase, but it’s tough to hear over the engine. But to be fair, I never listened for it before so I can’t say it wasn’t always there.

 

[Tx Jim]

Get a laser thermometer and check for overly hot hyd components.

 

[MMagis]

I have an infrared thermometer. Any particular components I should focus on?

 

[Tx Jim]

steering valve,FEL valve,scv(rear remotes) if equipped with them

 

[BAP]

Have you checked your hydraulic filter and made sure the intake screen is clean? Also, does the main hydraulic pump have the destroking kit on it? If it does make sure it isn't bleeding off the pressure. Check the coupler for the pump to make sure it isn't starting to strip out inside of it. It could also be the transmission pump going bad which feeds the main pump.

 

[MMagis]

I apologize, I’ve not made it yet to check the temps. I hope to today.
I have changed the filter and cleaned the intake screen. Checked for a destroking kit, but it doesn’t have one (though it needs one).
According to the schematics in the tech manual, or at least my interpretation, the transmission pump shouldn’t affect the supply of fluid to the main pump. However, I question the accuracy of the schematics. There is more than one in the manual, and they don’t necessarily match each other.
The manual does have a step by step guide to troubleshoot hydraulic problems, and we’ve tried to follow it to a degree. But it would actually be cheaper to replace parts, starting with the pump, than to buy all the tools required to follow the guide.

 

[MMagis]

I ran out at lunch to check temps. Let it idle for 5-10 minutes, then increased RPMs until it made it to full pressure. I worked the valves/steering for a few minutes and then checked temps. None really stood out as hotter than the others. Probably could have let it run for a bit longer, but everything basically stayed at the ambient temp after 15 mintues.

 

[Tx Jim]

I apologize, I致e not made it yet to check the temps. I hope to today.

According to the schematics in the tech manual, or at least my interpretation, the transmission pump shouldn稚 affect the supply of fluid to the main pump. However, .

Trans pump supplies oil to hyd pto,hyd hi-lo or reverser,brake valve,lube trans shafts """""AND supplies oil to frt hyd pump""""". Frt pump can pump supplied oil to hyd functions BUT can't SUCK oil

 

[MMagis]

That makes sense. At this point I feel like I’m at a “chicken or egg” stage. The main pump only builds pressure at higher RPMs, and even that will quit after a while. I’m not sure how to determine if it’s the main pump not working correctly, or the transmission pump not supply enough fluid. I did determine that a rebuild for the main pump isn’t an option. The kit offered by Deere is just a seal kit, and a call to the local hydraulic shop revealed that they won’t even work on this type of pump.
I appreciate all the help.