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Discussion Starter · #1 ·
Hi All,
It's been a while since I been active on the site and it looks different - I like the improvement.
Have a 2009 JD 3520 Cab unit 2000 hrs and a 366 front blade. Plowing snow tonight and the blade angle would change on
it's own intermittently - typically when pushing the snow. For example - It would go from a slight left angle to extreme left position.
All randomly - if I moved the dual SCV lever it seems I could regain control. But it would happen again and it happens
on either a right or left angled blade position.
Not sure exactly how the Cushion Valve on the Plow A Frame works but wondering if it might be diverting fluid to one cylinder or the other intermittently?
I get out of the cab and pull on the blade in one direction or the other and it won't budge so nothing appears to be physically broken.
Also - as I am writing this I am wondering if my right knee hit the SCV lock lever relating to regen?

Any thoughts from the hydraulic guys on how to diagnose/troubleshoot this would be appreciated.
Thanks
Tony
 

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Any fluid leakage at the cylinders?
If not, I'd have to suspect the CRV (crossover relief valve), maybe the springs inside have gotten weak and the blade is moving under too little pressure. I'm not sure if these are adjustable though like the one we
sell is.
 

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Any fluid leakage at the cylinders?
If not, I'd have to suspect the CRV (crossover relief valve), maybe the springs inside have gotten weak and the blade is moving under too little pressure. I'm not sure if these are adjustable though like the one we
sell is.
X2
 

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The CRV has a couple of spring loaded ball checks inside. One may have become dislodged.

I few years ago when I picked up a used 366 I had to rebuild one swing cylinder that had become corroded due to water intrusion. That was the easy albeit $$$ part. After reassembly the R/L hydraulics weren't working properly and I decided on a hunch to remove and disassemble the CRV.

I recall removing the side plugs and shaking out the pieces and parts, cleaning the valve with solvent and then reassembling it. Fairly simple arrangement. The plugs that screw into the casting locate and center the springs and ball checks.

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Discussion Starter · #5 ·
The CRV has a couple of spring loaded ball checks inside. One may have become dislodged.

I few years ago when I picked up a used 366 I had to rebuild one swing cylinder that had become corroded due to water intrusion. That was the easy albeit $$$ part. After reassembly the R/L hydraulics weren't working properly and I decided on a hunch to remove and disassemble the CRV.

I recall removing the side plugs and shaking out the pieces and parts, cleaning the valve with solvent and then reassembling it. Fairly simple arrangement. The plugs that screw into the casting locate and center the springs and ball checks.

View attachment 823060
Hi All,
It's been a while since I been active on the site and it looks different - I like the improvement.
Have a 2009 JD 3520 Cab unit 2000 hrs and a 366 front blade. Plowing snow tonight and the blade angle would change on
it's own intermittently - typically when pushing the snow. For example - It would go from a slight left angle to extreme left position.
All randomly - if I moved the dual SCV lever it seems I could regain control. But it would happen again and it happens
on either a right or left angled blade position.
Not sure exactly how the Cushion Valve on the Plow A Frame works but wondering if it might be diverting fluid to one cylinder or the other intermittently?
I get out of the cab and pull on the blade in one direction or the other and it won't budge so nothing appears to be physically broken.
Also - as I am writing this I am wondering if my right knee hit the SCV lock lever relating to regen?

Any thoughts from the hydraulic guys on how to diagnose/troubleshoot this would be appreciated.
Thanks
Tony
Thanks to all for replying so promptly.
No visible leaks from angle cylinders on plow.
Looks like Kennys UCRV is currently out of stock.
Need to try and have it ready for the next storm as I do
residentials with the machine.
Will try Superglidesport suggestion of cleaning and remove side plugs of existing valve.
Any recommendations on safe hydraulic solvents for such a cleaning - is it just a cleaning of the springs and ball checks or
is the solvent flushed through the valve body too?
Thanks again guys!
 
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Thanks to all for replying so promptly.
No visible leaks from angle cylinders on plow.
Looks like Kennys UCRV is currently out of stock.
Need to try and have it ready for the next storm as I do
residentials with the machine.
Will try Superglidesport suggestion of cleaning and remove side plugs of existing valve.
Any recommendations on safe hydraulic solvents for such a cleaning - is it just a cleaning of the springs and ball checks or
is the solvent flushed through the valve body too?
Thanks again guys!
I use mineral spirits around the shop and likely used it to clean the CRV, check balls and springs. OTOH, I removed the valve assembly from the hoses and hitch and cleaned it on the bench. Then gently blew it out with compressed air.
 
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Discussion Starter · #7 ·
I use mineral spirits around the shop and likely used it to clean the CRV, check balls and springs.
Perfect - Plenty of spirts here.
Will give it a go!
Thanks
 
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One quick comment: CLEAN, as in hospital operating room clean is essential for the hydraulic system! Clean your work area, your parts, your tools and your hands. Get a small container with hyd. oil in in. After cleaning parts, dip them in the oil... a "final rinse" and a rust preventive from the air and the acid on your skin!... and install. If you don't finish the same day, cover parts, discard oil, and start fresh the next day.

I don't know what the fittings are, but if they're NPT, use a paste type thread sealant and NOT teflon tape. If ORB, lube o-rings and do NOT over tighten! Bob
 

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Discussion Starter · #9 ·
Thanks to all again for commenting. Removed the valve from the front hitch mounting plate and disassembled, and visually inspected components. Nothing unusual was observed. Placed components in mineral spirits bath and then dried. Flushed out valve body and blew compressed air through it. Reassembled and reinstalled. No leaks, plow moves left and right without issue. We have more snow coming next week - lots more (26-27") if future forecast is correct. Have to see how it reacts when pushing snow. Thanks.
 

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Thanks to all again for commenting. Removed the valve from the front hitch mounting plate and disassembled, and visually inspected components. Nothing unusual was observed. Placed components in mineral spirits bath and then dried. Flushed out valve body and blew compressed air through it. Reassembled and reinstalled. No leaks, plow moves left and right without issue. We have more snow coming next week - lots more (26-27") if future forecast is correct. Have to see how it reacts when pushing snow. Thanks.
Success! Happy we were able to help get you back in business!
 
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Discussion Starter · #11 ·
Since the reassembly of the cushion valve we have had a couple of large snow falls and the blade kept the angle it was set at while pushing
full blades of snow. Although I didn't see anything unusual with the valve components when apart it is now working fine. Thanks to all.
 
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