Snow Kubota 5240 third function valve sticking

[rfc143]

Whenever it's below freezing, my third function valve sticks until enough warm oil goes through it (usually as much as 45 minutes, by which time I'm nearly done blowing). It typically goes end to end once the button in the cab is pressed; I'm sure it's not an electrical problem.

I chalked it up to sticky hydraulic oil, so put a 60 watt light bulb (with reflector) aiming up directly beneath the valve near the right hand door of the tractor, and covered the cover with a towel, and left it overnight. The low was around 5 degrees F.

Voila! Started the tractor and moved the blower chute left to right and it stops on a dime and works perfectly.

Now I want to replace my Kludge light bulb heater with some short heat tape (60 watts is now known to work OK) around the body of the valve, and just tie in the AC to my block heater circuit via a cube tap.

Does anyone have experience with any roof ice demelters or other kind of water pipe anti freeze tape that might do the job?

 

[PEJ5]

Hydraulic oil does not freeze at that temperature, but water does. Maybe there is a moisture issue. Repairing the symptom rather than the problem is sometimes the easier fix, especially when it is too cold to work with bare hands! This is the first thing that comes to mind. It should keep the metal valve warm enough and 12 watts will not melt the hoses.
https://www.homedepot.ca/en/home/p.6-ft-electric-pipe-heating-cable.1000176069.html
Someone else may know how to fix the root cause.

 

[rfc143]

Six feet might be too long, but whatever's "left over" after wrapping the valve I can wrap the Pressure line coming from wherever it comes from. I'm sure the hydraulic oil is probably not frozen, but it sure is sticky at those temps. Just filling the transmission at those temps it "glugs" out thick as molasses. I think it's just sticking up the valve a bit, preventing the spool from moving when cold.

 

[moship]

I've used adhesive silicone pad heaters to preheat lubricants (oil pan, rear end, etc...) before. They come in a variety of shapes. Perhaps they would fit your needs.

Example:
https://www.amazon.com/FYSETC-Printer-Silicone-Adhesive-Heating/dp/B07GDDC77W/ref=sr_1_2_sspa?ie=UTF8&qid=1547587862&sr=8-2-spons&keywords=adhesive+silicone+heating+pad&psc=1

 

[rfc143]

Well, I think I'm going to have to go down the road PEJ5 suggests (Fixing the problem). I tried three feet of heat wire, stated on the package to be 50 watts. That was wrong; I measured it at about 20 watts. It sort of worked, but I found, even with a 60 watt light bulb, it works initially, but as soon as I start out in sub zero temps, it "freezes up" again.

I did find that at low rpms, I can get it to stop anywhere I want, but at high rpms, pushing the button opens the valve and it stays open. It's a pain though to stop and reduce the rpms whenever I want to turn the chute. I'm not sure I can (or should) attempt to disassemble the valve. It's a Nachi that I assume comes pretty standard on Kubota tractors. Would replacing the valve be the next step? Ideas welcome.

 

[countrybumpkin]

I’d remove the coils and see if there is any rust or corrosion. May even have moisture in it, causing it to stick when below freezing.

Here is one of a few videos of what’s inside one.

Explaining Directional Valve Repair - Full Dismantle and Reassembly - YouTube

 

[rfc143]

Here is one of a few videos of what’s inside one.

Wow! Thank you for that, Sir. I had no idea they were that simple to dis-assemble. I shouldn't have to worry about fluid draining from the manifold while off should I? It looks like a D03, so I might be able to put a cover plate on it while looking at the valve. But before that, I'll just remove and inspect the coils as suggested. Thanks again.

 

[countrybumpkin]

You will get fluid drain from the manifold if you remove the valve, it will depend on valve placement compared to the hoses that attach to it.

 

[rfc143]

Well, I'm beginning to think the temperature effect was a complete red herring. I've tried all manner of heat, but once I head out, I find that at full revs, the valve sticks in either direction; If I back the revs off to idle, I can actuate the valve momentarily and it stops when I release the button. Have disassembled the valve; no rust; springs look good; electrical circuit/buttons all check out.

What would cause a spool valve to stick open at high flow but not low flow? Scratching head.

 

[greenrider1]

I found that my third function valve stuck open while experimenting with restrictors to slow down my plow swing. There was a fine line between the orifice size being too small and sticking, vs too large and allowing the plow to slam violently side to side. I'm guessing if there isn't anything plugging the valve, the hydraulic fluid is simply too thick when it's that cold. Are you running the super UDT2? That really helped reduce the hydro whine in mine when it's really cold out. I don't believe they come from the factory with the super udt2, since Kubota has no idea what part of the country each individual tractor will be used, but I could be wrong. It would be worth trying the better fluid, assuming yours doesn't have it, to see if it cures your problem.