Instructions: How to disassemble, clean, and reassemble loader control valve

[jodebg]

Wondering if someone would post the service manual instructions on how
to disassemble, clean, and reassemble a LA402 loader control valve
on a kubota B7800. Thanks for you help.

 

[ADDfarmer]

Figured that this thread was appropriate for tagging on to...

The seals on my valves have been leaking at the top of the block for a while now I had the valve body attaching bolts break (or fall out- not sure yet) so it looks like I'll take the time to finally fix the leaks: I've had seals sitting on my shelf for quite some time.

Am I correct in my understanding that the valves come out from the bottom of the valve body? I remove the cotter pins on the linkage from the top and pull the caps at the bottom off (two long ones of equal size) and then what? What needs to be disassembled at the bottom side to release the valves? Will I be able to gently catch parts dropping out or will they be looking to shoot out?

Also, is there any special tips/notes on removing and reattaching the threaded hoses (not coupler ones)? My loader is currently non-functional and is lifted in the air. Do I need to drop it in order to ensure there's no pressure in the system?

 

[100 td]

There is a full service manual for a BX1860/BX2360/BX2660/LA203/LA243 which will be very similar and give you all you need I expect, as well as the parts manual with exploded diagrams for the LA402 here
http://www.kubotabooks.com/AutoIndex/index.php?dir=Tractor Owners Manuals/
http://www.kubotabooks.com/AutoIndex/index.php?dir=Loaders and buckets/
With regards to working on the system, ensure there is no hydraulic pressure in the system before any work, and ensure there is no possibility of any hydraulic pressure being developed by a sling slipping if holding a boom in the air. All implements must be grounded before any hydraulic components are touched. Disconnect battery so that there is no chance anyone could start the tractor while hydraulics are being worked on.

 

[ADDfarmer]

Yeah, saw the manual on the loader. It's still not clear, though looking again they do seem to show the valve coming out the bottom (Page 21). Some of the issue is that they have alphanumeric indexing on some of the parts but these don't show up in the parts list (so I really don't know what they are).

I'm leaking out the dust seal (part #15), which I believe isn't what is responsible for the actual leak. I suspect that it's the o-rings: as listed as part numbers: 030/080, 040/090 and 060/110. I'll have to double check what o-rings I got from the dealer: I don't recall getting six, maybe four?

I guess that I don't need to mess with anything shown at/from the bottom of parts "P" and "F." Just unscrew those two parts and then the valves pull/fall out?

Reading parts diagrams is one thing, actually wrenching on something (without a service manual) is another. And, for whatever it's worth, parts diagrams don't show torque specs.

 

[100 td]

Tightening torques are shown in the tables in the workshop manual, page 8-G6, 364 of 391

 

[100 td]

Also if you mark your spools prior to disassembly you can generally spin them 180 degrees which takes up a small amount of wear depending on the actuator lever design. Having had a quick look at the parts diagram I would have just purchased 2 x 160 seal kits, then a 150 if you intended to pull the relief valve. But what ever you do, don't take it for gospel, I'm no egg-spurt!
(S.No.;>=50001 if we are looking at the same page, Reference:01B00503, Page:9, 21 of 42 in the pdf)

Chase up North Idaho Wolfman if you want the good oil!

 

[ADDfarmer]

Poked around and found my seals. Only have the top dust seals. So...

Will be ordering the seal kit. Wondering, however, whether the detent kits would be needed as well: 020 and 070 (not sure why they're different).

Thanks for the tip on rotating the spools. Not real sharp on any of this nomenclature, though I've operated this tractor for over 900 hrs now!

 

[100 td]

Should have mentioned, only if the spools are "wholly" round without flat detent positions or locating bosses etc., which they probably are but be sure to check.
If your valve is sloppy/not sitting in the detent position, or grabbing when trying to move from the detent position they may be worth replacing, but if they feel good then I would go just for seals. But once again, chase up NIW or someone else for the good oil!

 

[100 td]

Wondering, however, whether the detent kits would be needed as well: 020 and 070 (not sure why they're different)

2 different spools, one will have float, maybe regen on the other so different detents I expect?

 

[ADDfarmer]

OK, thanks for helping to educate me

I ended up bolting the loader valve back on as I discovered that the original bolts worked themselves out rather than shearing off (yes, that probably wouldn't have been hard to do). So... I'll continue with my procrastination (I can't really have the tractor down right now), but will order the seal kit: the detents would appear to be fine because everything works normally (just have the leaking/weeping).

I'll report back on how the re-seal operation goes.