Deere 855 bucket float

[WinterDeere]

So, my 855 bucket control would never stay in the float position. In fact, it's always been hard to push all the way forward to float, but you can get it there with some applied force.

Last week I was moving some snow with the bucket, and was indeed forcing the lever forward, to make the bucket float. After some time, it actually started staying in float, and life was good... for a few brief moments. Then, I lost my bucket curl function.

The fix for the bucket curl was easy... a cotter pin on a bit of the SCV handle linkage had sheared, which was replaced with minimal cussing and frustration. Then I was back to no float position, and I realized the reason I had the float position working well for a few minutes there was that one of the two tie straps (item 24B in image below) had popped off after the cotter pin had sheared, but before the pin (item 23) had worked its way completely out. In other words, with only one of the two 24B tie straps connected, the bucket float detent seems to work better.

Any suggestions? I assume a completely disassembly of the linkage is in order... but where does this "detent" exist? Is it a function of the linkage, or something internal to the SCV. I know the SCV controls float, but what physically holds the handle in the float position?

Thanks!

 

[techwrtr2]

It's in the valve.

 

[rinconryan]

Sounds like your linkage is getting wore out. Had problem with dump on mine. Linkage was moving sideways instead of pushing on valve so replaced pins with bolts, washers, and lock nuts. Works great now! Look at the linkage as you move the lever around and see whats moving. My guess is the 'L' shaped link is your problem.

 

[techwrtr2]

I completely replace all of my linkage at one time. Worked like new after.

 

[kennyd]

The detents are attached to the rear of the valve, opposite the linkage:


SELECTIVE CONTROL VALVES (FLOAT AND REGENERATIVE) (55 SERIES ONLY)
SELECTIVE CONTROL VALVES (FLOAT AND REGENERATIVE) (55 SERIES ONLY) (CONTINUED)
Cart KEY PART NO. PART NAME QTY SERIAL NO. REMARKS
1 M800705 BOLT 4
2 M800707 PLATE 2
3 M800710 BALL 4
4 M800714 SPRING 1
5 M800713 GUIDE 1
6 M800712 HOLDER 1
7 M800703 HOLDER 2
8 M800701 SPRING 2
9 M800702 HOLDER 2
10 M800698 PLUG 2
Cart KEY PART NO. PART NAME QTY SERIAL NO. REMARKS
11 M800684 O-RING 2
12 M800700 SPRING 2
13 M800699 POPPET 2
14 M800704 COVER 2 DETENT
15 M800693 PLATE 2
16 M800696 SEAL 4
17 CH10569 PACKING 4
18 M800697 PACKING 2
19 AM875175 CONTROL VALVE 1
20 M800716 BUSHING 2
Cart KEY PART NO. PART NAME QTY SERIAL NO. REMARKS
21 AM875176 SUPPORT 1
22 19M8553 SCREW 4 M6 X 16 (HS, HEAD MARKED 12.9) (SUB FOR M800695)
23 AM875174 CONTROL VALVE 1 REGENERATIVE
M802392 PACKING 1 (ADDED TO PREVENT WATER FLOW INTO VALVE DURING AIR LEAK TEST)
24 M800706 HOLDER 1
25 R63075 BALL 1 (SUB FOR CH18341)
26 M800709 COMPRESSION SPRING 1
27 M800711 SPRING PIN 1
28 M800708 DETENT 1
29 ........ CONTROL VALVE 1
Cart KEY PART NO. PART NAME QTY SERIAL NO. REMARKS
30 M800694 SUPPORT 1 LEVER
31 19M8553 SCREW 2 M6 X 16 (HS, HEAD MARKED 12.9) (SUB FOR M800695)
32 AM875172 CONTROL VALVE 1 FLOAT
M802392 PACKING 1 (ADDED TO PREVENT WATER FLOW INTO VALVE DURING AIR LEAK TEST)

 

[WinterDeere]

Thanks, guys! Seeing the detents are internal, I'm still betting on wear in the linkage. I cannot imagine any other reason it worked briefly when the linkage was falling apart, but not when assembled. I guess I have to get the seat and sheetmetal off of the machine, and start looking at that, first. Hopefully that's what I'll find, as it sounds much more fun than pulling apart the SCV internals.

I pulled out the shop manual and read thru this chapter a short time ago. Definitely not a problem for me to rebuild this valve, but would like to avoid it, if I can!

 

[gregz]

Please keep us (me)posted on your results of the linkage rebuild. Parts and #'s as well. My Lever will not stay in the float position so this post will be helpful.
cheerz
gregz

 

[Grumpy Old Man]

Please keep us (me)posted on your results of the linkage rebuild. Parts and #'s as well. My Lever will not stay in the float position so this post will be helpful.
cheerz
gregz

Same here !

 

[WinterDeere]

Okay... found a few minutes to pull the sheetmetal and inspect this evening. Problem appears to be simple. Referencing the diagram I posted above, lever item 5 is not pivoting wihtin the block at the bottom of control lever item 3. So, when I have the tie straps item 24 connected, I'm unable to push the control lever far enough forward to float the bucket. If I disconnect tie straps item 24, the float works just fine. Unfortunately, trying to force it over the last several months has likely put a lot of undue stress on the actual valve piston, but being a Deere... it took the abuse.

Can someone with a working control lever please confirm that lever item 5 should indeed pivot in the main block at the bottom of the control lever item 3? Mine seems frozen, such that lever 5 always moves fore/aft, when you push the control lever fore/aft.

Getting at this was not difficult. You crank up the mower deck height control, remove the four screws from the plate that holds the mower deck control, and lift that panel out. Then you remove (unscrew) the knobs from the hi/lo range and pto selector levers, and reach under the fenders to remove the four screws holding that panel in place. A little finagling, and that panel comes out, then you can get at this linkage pretty easy.

 

[WinterDeere]

Just to make things clearer, here's a photo of what I was discussing above. Here, I have one of the tie links (24B) disconnected, and all works well. When I connect both tie straps, things are over-constrained, and I can't get the lever into the float position. It seems to me that if lever 5 was able to pivot in that block at the bottom of lever 3, all would be good. Mine seems frozen, but I'm guessing it should pivot.