John Deere 855 SCV Work

[Doug Vee]

Is anyone aware of a kit to rehab the control linkages for the SCV? Also, is there a reseal kit available for the valve body itself? Is the resealing of the valve body something that can be performed in frame?

The control lever is getting pretty loose goose, and the float function has never been available to me since I have owned the machine (10ish years or so). Also, the valve body seems that it is wetter than it should be, and I'm thinking some O-rings need replacement. The machine has just over 1000 hours, 1990 model year, with power beyond plumbed and has the 7 backhoe and the 70 loader.

Thank you,

Doug

 

[bmaverick]

Is anyone aware of a kit to rehab the control linkages for the SCV? Also, is there a reseal kit available for the valve body itself? Is the resealing of the valve body something that can be performed in frame?

The control lever is getting pretty loose goose, and the float function has never been available to me since I have owned the machine (10ish years or so). Also, the valve body seems that it is wetter than it should be, and I'm thinking some O-rings need replacement. The machine has just over 1000 hours, 1990 model year, with power beyond plumbed and has the 7 backhoe and the 70 loader.

Thank you,

Doug

Doug, not all the JD855 are capable of SVC. You have to verify per the tractor ID plate on the lower back end near the PTO output spline shaft.

TractorData.com John Deere 855 tractor information

www.tractordata.com

 

[Doug Vee]

Doug, not all the JD855 are capable of SVC. You have to verify per the tractor ID plate on the lower back end near the PTO output spline shaft.

bmaverick,

I apologize, but I do not understand your reply. If my 855 can operate the model 70 loader, does it not have a selective control valve(s)?

Thanks again for your time.

Doug

TractorData.com John Deere 855 tractor information

www.tractordata.com

 

[oldnslo]

Doug
Deere parts shows a decent parts breakdown for the direction control valves. I did not see a seal kit listed but I also could have easily missed it. Can you tell if leaking between the valve sections or just around the ends of the spools?

Detent assembly can usually be cleaned and or rebuilt.

No clue if this an in frame job on 855. You would need decent access to both ends of the valve to replace spool seals and detent assembly.

 

[bmaverick]

bmaverick,

I apologize, but I do not understand your reply. If my 855 can operate the model 70 loader, does it not have a selective control valve(s)?

Thanks again for your time.

Doug

Doug, you would have to find the tracto serial number on the rear ID plate by the PTO output. M00855B010001 and higher s/n would allow a SCV interface on your machine. It's that simple. Because the hydraulic system either came with the interface or was not added to the sunstrand die cast on the tractor. So yes, look closely at the s/n of your machine. It's that smple to find out Yeah or Nah to add the optional SCV to your machine.

 

[oldnslo]

Doug, you would have to find the tracto serial number on the rear ID plate by the PTO output. M00855B010001 and higher s/n would allow a SCV interface on your machine. It's that simple. Because the hydraulic system either came with the interface or was not added to the sunstrand die cast on the tractor. So yes, look closely at the s/n of your machine. It's that smple to find out Yeah or Nah to add the optional SCV to your machine.

First post says has 70 loader and number 7 back hoe and that loader levers are loose and valve is leaking. Was there different options for where loader valve was mounted on the 855? Was there also different option on how the the back hoe was plumbed?

Just curious since have no direct knowledge of 855 options.

 

[dfkrug]

The control lever is getting pretty loose goose, and the float function has never been available to me since I have owned the machine (10ish years or so). Also, the valve body seems that it is wetter than it should be, and I'm thinking some O-rings need replacement.

Your FEL joystick valve prob looks like this one from one of my 955s. All is accessible after removing seat and its support bracket. Fender removal helps, too, but may not be necessary.

The joystick's heim joints and some of the brackets get pretty worn as most owners don't oil them. At the time I did mine, JD parts were available and reasonable. Now? Dunno.

But I just ordered a full set of 6 replacement heim joints for my backhoe that look better-made than the original. About $20 total. You can also fix the worn holes in those brackets by drilling them out and inserting a bushing.

 

[Doug Vee]

Doug
Deere parts shows a decent parts breakdown for the direction control valves. I did not see a seal kit listed but I also could have easily missed it. Can you tell if leaking between the valve sections or just around the ends of the spools?

Detent assembly can usually be cleaned and or rebuilt.

No clue if this an in frame job on 855. You would need decent access to both ends of the valve to replace spool seals and detent assembly.

The area around the end of the spools looks pretty damp from hydraulic oil. Also damp around the cap screws going into the flow divider.

The largest leak I have found is where the pressure line to the power beyond comes out of the top of the case. In order to disassemble it to replace the O-rings, it looks like I have to start removing hydraulic lines from the top of the SCV, at least one if not all of them, to have access and clearance to turn the fitting.

It doesn’t look like it is too tough to remove the flow divider and the SCVs. The fun probably really starts when you start pulling the spools out.

Thanks for the reply,
Doug

 

[Doug Vee]

Your FEL joystick valve prob looks like this one from one of my 955s. All is accessible after removing seat and its support bracket. Fender removal helps, too, but may not be necessary.

The joystick's heim joints and some of the brackets get pretty worn as most owners don't oil them. At the time I did mine, JD parts were available and reasonable. Now? Dunno.

But I just ordered a full set of 6 replacement heim joints for my backhoe that look better-made than the original. About $20 total. You can also fix the worn holes in those brackets by drilling them out and inserting a bushing.

Yep,

Mine looks very similar to yours. It looks like I have a long phone conversation with the John Deere parts person in my future.

Concerning bushing the shaft holes, I have never tried to source bushings for a project like this. I suppose the bushing material hardness, the OD and the ID is the pertinent information, but where does one source bushings?

Thanks for the reply,
Doug

 

[dfkrug]

Concerning bushing the shaft holes, I have never tried to source bushings for a project like this. I suppose the bushing material hardness, the OD and the ID is the pertinent information, but where does one source bushings?

I use eBay for most of my parts of this type. You can also try someone like Grainger.

First, I differentiate between "bushings" and plain bearings. The pins used for your FEL joystick do wear, as well as do the holes in the brackets, and the pivot holes in the valve spool. Fortunately the spool pivot holes I have seen seem to be harder than the pins or holes in the brackets. The system can be designed where the pins are softer than the other wear surfaces, which I prefer.

I would buy some steel bushings and pins to fit, of the same ID as the ID of the spool pivot hole. Verify the spool pivot hole is not too worn.

Drill out the brackets to the OD of the new inserts. Chances are you will have to drill a little too big and weld it in. You may be able to shoot for an interference fit, if you are lucky and want to do the extra work.

I have done this for small holes like this, as well as 1' or bigger loader pin holes.

You can also plug your sloppy holes with a welder, then drill them out.

 

[Doug Vee]

I use eBay for most of my parts of this type. You can also try someone like Grainger.

First, I differentiate between "bushings" and plain bearings. The pins used for your FEL joystick do wear, as well as do the holes in the brackets, and the pivot holes in the valve spool. Fortunately the spool pivot holes I have seen seem to be harder than the pins or holes in the brackets. The system can be designed where the pins are softer than the other wear surfaces, which I prefer.

I would buy some steel bushings and pins to fit, of the same ID as the ID of the spool pivot hole. Verify the spool pivot hole is not too worn.

Drill out the brackets to the OD of the new inserts. Chances are you will have to drill a little too big and weld it in. You may be able to shoot for an interference fit, if you are lucky and want to do the extra work.

I have done this for small holes like this, as well as 1' or bigger loader pin holes.

You can also plug your sloppy holes with a welder, then drill them out.

dfkrug,

Thanks for your thoughts on this. I appreciate it. I will check into eBay as a source.

Now, to continue on with the discussion of the SCV's, the front valve is the regenerative valve. I can feel the detent when I push past the normal travel, but it does not stay in place. Since I was not aware of this feature, I did not miss that it was not holding in place, but did always wonder why there was a "click" when pushed all the way. I assume the spool should stay in that position until physically pulled out of the detent?

The rear valve, with the float function, I have never felt the detent when pushed past the normal down function. I have the linkage removed from both. spools. I pushed the rear spool past with a pair of pliers. I think I feel the detent position, but it does not seem to want to remain in the detent position. Again, I assume this should remain in position until pulled back to normal operation. Should it stay in the detent?

Thanks for your time.
Doug

 

[dfkrug]

The regen function is not detented, the float function is detented.

 

[Doug Vee]

The regen function is not detented, the float function is detented

 

[Doug Vee]

Thanks for the reply. I get the feeling the float detent is not functional.

I browsed the 70 loader manual. It seems funny to me that there is no real specific mention of the regen function and almost no mention of the float function. At least that I could see. I don’t see as well so used to though.

 

[dfkrug]

My loader was a 70A model. Dunno what the differences are between that and the 70.

It is amazing how many folks I meet who don't even realize their tractor has a float function. I suppose disuse could also make it so the detent balls get gummed up and stop their function.

 

[Doug Vee]

My loader was a 70A model. Dunno what the differences are between that and the 70.

It is amazing how many folks I meet who don't even realize their tractor has a float function. I suppose disuse could also make it so the detent balls get gummed up and stop their function.

Another funny thing is, this is the second 855 I have owned. I have owned 855's for 20 years. I am the kind of person that likes to have the factory documentation for equipment. I also read the manuals...but if the manuals don't describe the operation fully, how would anyone know?

Also, the decals on the fenders apparently are not nearly as durable as the tractors. There is no real discernible information remaining on the loader fender. The goofy symbols might have had me questioning what they mean, but they are not there. Now that I know about it, I want to pursue this as a project.

Doug

 

[Doug Vee]

The regen function is not detented, the float function is detented.

That makes sense.

 

[oldnslo]

Do you gave to push past a stop to go into regen? I believe most if not valves have a stop before you get to regen similar to going into float.

Regen mechanisms can get gummed up over time especially if they are not used. Use care when taking them apart since there is almost some balls and or springs that will fly out and vaporize into thin air.

 

[Doug Vee]

Do you gave to push past a stop to go into regen? I believe most if not valves have a stop before you get to regen similar to going into float.

Regen mechanisms can get gummed up over time especially if they are not used. Use care when taking them apart since there is almost some balls and or springs that will fly out and vaporize into thin air.

I haven't checked into it too much, as I just reassembled the tractor after having repaired the hydraulic leak in the power beyond circuit. I did discuss the parts availability for these SCV's with the JD parts man. It appears that many of the parts are NLA, so this might be more of an academic discussion more than anything. Since I never even knew the valves had those features, I never missed them.

Thank you for the reply,
Doug

 

[Doug Vee]

I have the 855 whole again. The loader linkage action is much improved. I did not pursue and bushing installation, though I have a pretty good idea where bushings would help if I were to take on that project. The loader lever has two holes that are 90 degrees to each other. Those two holes seem to be where the play is. I will probably leave as is, unless I am looking for another project sometime in the future.

Concerning the float and regen functions, the regen is functioning. I had never really noticed it before, but it is definitely there. The float function is not available. I don't think I will pursue correction of the float function. The only place I could think of to use it would be for snow clearing. Since I have a stone driveway, even then it would not be really that much of a help to keep rock out of the grass. It might be good for back dragging with the bucket, but, as I said before, it has never worked, so I don't miss it. Maybe it might be a future project to remove the detent assembly, clean it up and reassemble to see if that might correct the problem.

Anyway, I am satisfied with the much improved SCV action now.

Thanks for all the replies.
Doug