SCV rebuild flying blind - are these standard seals? Also - dual restrictors a problem?

[chilly81]

I'm trying to fix a slow JD 67 loader on a JD 750 tractor with a SCV off a ford or new holland ("diesel kiki" branded). I can't find any parts or service info for it, and am new to hydraulics, but generally mechanically competent. So just a couple questions

QUESTION: Are the external spool seals in this pic standard, or would that be a part specific to this SCV (so don't mess with them). I'd like to flush things out with diesel or even brake cleaner if I can get all the non-metal parts out.

QUESTION: The 67 backhoe has built in restrictors and the tractor has a single circuit with a system PRV. This aftermarket SCV has a built in PRV. It also appears to have what I'm guessing are restrictors (2nd pic). Would this be a cause for slow movement? 2 restrictors inline (SCV and in the loader?). If I remove them to test, will it just make things move fast? Not danger of overpressurization? (the system PRV is working properly)

 

[MTGreen]

I had a tractor with a Diesel Kiki injection pump that was impossible to find parts or even schematics for -YMMV.

You would need to measure the ID, OD, and depth of those seals to see if you could locate replacements. The fact that they were made by NGK is promising.

If the mismatched component SCV is greatly oversized in terms of GPM for your application, no amount of messing with it is going to change speed issues.

Have you considered just upgrading to a modern type joystick SCV?

2 Spool 10 GPM Joystick Loader Control Valve w/Float Chief 220957 | Chief | Brands | www.surpluscenter.com

2 Spool 10 GPM Joystick Loader Control Valve w/Float Chief 220957, Chief, 2 SPOOL JOYSTICK LOADER CONTROL VALVE WITH FLOAT Brand new, CHIEFChief,220957,

www.surpluscenter.com

 

[chilly81]

Oh wow - that is really good news that a replacement is that reasonably priced. I think this is about 5GPM, but the loader has restrictors built in. So that might just drop right in? Would a valve like that have internal restrictors? I don't see it referenced in the specs - is it something you might add for your specific case if necessary?

OK I think I'll just use simple green and blow it out - not risk dealing with seals then. It really looks nice and clean inside and spools don't look worn at all, so I'm hoping this double-restrictor is the issue, and maybe P.O. just dealt with it being slow. it is like 1/4 the speed of the backhoe though - pretty tedious, even for a homeowner use though.

Just to clarify - did you mean 'undersized' SCV, nothing can help (vs oversized)? This is my first foray, so still just learning how it all works.

That helps a lot though - thanks.

 

[chilly81]

Well everything looked good, clean and not visibly worn in the valve, and I did remove those restrictors, and unfortunately not much change.

I did just realize that the JD 67 loader has a integral valve body in it which I thought I had read was a restrictor. Turns out it's a relief valve between the two sides of the lift circuit. Not sure what the point of that is - maybe physical or something - if you drop a giant weight on the loader while it's up somehow, it would allow it to drop if too heavy, rather than tipping or breaking? Seems like the system PRV would handle any operating sitations. Anyway, I'll open that up next and see what it looks like inside.