Snow Plow Hydraulics Problem

[Jackfr]

I have an early 1990's Pathfinder Snow plow setup on an 1984 F250. With an engine mount hydraulic pump and a remote control valve under the hood. It has served us well, but now when I drop the plow it is dropping very slowly(approx. 30 seconds to drop). This appears to be getting progressively worse and I need to repair this before the next storm.

I have checked the remote linkage it's ok the spool travels full throw in both directions. The power angle works fine in both directions. I have disconnected the line from the lift piston at the valve and the piston drops fine with the line removed. It sounds like the relief valve is operating partially when ever I try to operate the valve either in the up position or either angle, but it still operates. I have not disconnected the return line from the valve to the pump as the oil should be circulating right??

Does anyone know if there is a rate of drop adjustment on this valve as there is on newer plow setups and where it is?? Is this setup an open or closed center? Is there some way to repair this valve? Where can I find a replacement valve? I've looked but everything now is focused on the newer electric setups.

I tried contacting Pathfinder but only got a recording left a message but no return call. The valve was made by O.E.M. Hydraulics in Ohio, but I think they are out of business as there was an auction listed last year. The original parts diagram I have from Pathfinder only shows the valve no blowup of the valve parts.

Any help or ideas would be realty appreciated!

 

[mrmikey]

Try this again, my post was lost in cyberspace lol. Check the hose, if it deteriorated internally it could be acting like a check valve. Same thing happens quite often in brake lines....Mike

 

[Jackfr]

Which hose? I disconnected the one to the lift piston at the valve and the and oil easily flows freely out when the piston is pressed down (closed). Do you mean the return line from the valve to the pump?

 

[Leejohn]

The 1st picture of the valve it looks like the spool on the left is not going all the way in. I'm going by the wear marks on it. I know you said the spools were going all the way in and out, but might want to recheck.

 

[Jackfr]

I'll recheck that one. But it shouldn't affect the lifting piston as that one is for the right/left angling and that seems to be working ok. The one on the right is the lifting/dropping spool.

 

[Buckgnarly]

Check the low pressure return line, do you have an inline filter? If so, delete that and try it. Sounds like the return line may be messed up not allowing the fluid to return from the cylinder to the pump/reservoir.
I chased a problem for WEEKS with my old speedcast style underhood, turned out to be the pressure line. Brand new it had restrictions in it that was causing overheating issues.

It is an open system, and now that I think about it, if the low pressure return was stopping flow you would see the pump overheating...is it?

 

[Jackfr]

No the pump is not overheating. But maybe there is a restriction in the return line between the valve and the pump/reservoir causing the slow drop. I just picked up some return line and will replace it and see what happens. I found a valve but they want $400 for it.

 

[mrmikey]

Which hose?

Like Buck said above, the return line from the valve. The angle lines, although only single acting, are pressurized return by the opposing cylinder so you night not notice any restriction like you would on the lift cylinder being gravity. There's not much left it could be as you've checked everything else....Mike

 

[Jackfr]

It was the low pressure return line from the valve to the pump/reservoir. Replaced with new 3/8" hose and it is now working fine. It even lifts and angles quicker! Thanks for the help

Jack

 

[mrmikey]

You're welcome, glad you got it fixed and thanks for the update.....Mike