Deere 2555 scv teardown tips

Does anyone have any tips on breaking these down and repair? They look complicated.

Would be best to have a book for the first few times. It is crucial to get the cams back in the proper way and the clearance of the cams to the valve rollers is important too.
Might be simpler to ship it to Tim S to repair for you. You could send it here but the cross border thing gets tangled up by times.

I have the repair manual, didnt know if I had to dodge flying springs. My flow control levers are stuck on rabbit. Do you think i could get them to release by applying a heat gun and blaster? Pull front cover off to fix, or break down whole thing?

My hi-lo wont kick up into high. I looked through the fill cap and I have a flow of oil just in front of where the rockshaft comes out the right side.

(quoted from post at 21:29:06 11/22/17) I have the repair manual, didnt know if I had to dodge flying springs. My flow control levers are stuck on rabbit. Do you think i could get them to release by applying a heat gun and blaster? Pull front cover off to fix, or break down whole thing?

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I didnt have any problem moving them before but it has been sitting while I put in a new hydraulic pump and a/c

(quoted from post at 15:35:16 11/22/17) My hi-lo wont kick up into high. I looked through the fill cap and I have a flow of oil just in front of where the rockshaft comes out the right side.

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Hyd oil flow you see in hyd filler opening could be scv or rockshaft valves not seating unless scv return oil is routed to hyd oil ported filter cover

That oil you see will not have much to do with the hi/low issue,

Jim is this SCV the same as older models that required the OTC tool to establish neutral and adjust pressure and return valves .

IIRC the scv's are similar to the earlier style & I think a special OTC is required when adjusting poppet valves with a dial indicator.

I have been told that its possible to back return valves off 1/8 turn and pressures valves off 1/4 and not use dial indicator I have never used this method . If it would
work it may be helpful for peps without dial indicators .

Tim is correct in that that flow of oil has nothing to do with your Hi-Lo problem. The oil coming from the SCV valves is from the high pressure side of the system.

The Hi-Lo is ran off the charge/transmission pump pressure. It not shifting into high is usually one of several things.

1) Cracked internal steel line going down to the clutch pack.
2) Blown sealing ring in the clutch pack itself.
3) Cracked internal PTO control line causing a leak in the charge pump circuit.

Anyone of these require a transmission to clutch housing split to fix. There is almost nothing you can repair on the Hi-lo that is external. The only thing I can think of that MIGHT cause your problem that is externally repairable is a blow oring on the steel hydraulic lines where they go into the control valve. You need to remove the gear shifter housing. There will be four steel lines sticking up that the valve/shifter cover slides over. There are orings in the housing that seal between the lines and the housing. While you have it off look down in to the clutch housing at the steel lines. Them being broken or cracked is common. You can check them by blowing compressed air into each line. IF you have an internal leak you will be able to hear it leaking air.

You need to hook up a pressure gauge in the charge pump circuit and work the PTO and the Hi-Lo and see what the pressure does. I would bet that it drops when working one of these.

Also does your main hydraulic pump chatter if you use the hydraulics at lower engine RPMs????

In answer to your original question is that you need several service tools to properly service the SCV valve. The valve seat lapping/grinding tool and setting plate being mandatory. Just throwing new valves in the old seats will just about always leak.

Truthfully send them to TimS on this site. He can overhaul them and pressure test them for less money that you can buy the required tooling for.

I wish you luck as shifting troubles are usually just the beginning of hydraulic troubles on the Mannheim JD tractors. They CAN be fixed but it requires knowledge/skill, time/labor and MONEY.

P.S. Have you drained the hydraulic oil and checked the sump screen??????? Any thing plugging that screen will cause the hydraulic functions to act funny. If you find anything in the screen stop using the tractor until that problem is repaired. Running it that way will pump garbage throughout the system. Last one I repaired that had that done took close to $10K to fully repair it. I am not joking about that cost either.

First thing i did was change oil and filters, screen only had a couple specks of black stuff. Cut filter open and didnt find anything abnormal. My first Deere, I thought it was all gears until I learned of the hi-lo. Bought a parts and repair manual and was amazed at all the parts in the machine. I'm used to 800 series Fords. No chatter in pump. I was pretty sure I didnt have that oil flow before I moved the SCV levers while it was running. I may have just missed it when I was looking for oil spray in there before. It drives fine in lo just moving it around. I havent revved it to see if it will shift into hi. I wont drive it until i find the problem.