Winter is coming...
This is the hydraulic unit off of my neighbor’s snow plow that he picked up (used, non-working). He’s got the mechanical stuff under control, but I told him I’d be willing to check out the hydraulics. TBH, I don’t know much about these, but I managed to find some PDFs of the owner’s and service manuals so I don’t mind digging into this thing to see what’s up. Plenty of time before the next snowfall (I hope).
Near as I can tell, this appears to be what Western calls a “ISARMATIC Mark IIIa” (cable-operated). Hooked up to 12V power, the motor would run, but the lift ram would not move. Plenty of fresh, clean ATF in the pump housing, so something else is going on here...
The first thing that caught my eye was the orientation of the “Hydra-Turn” 4-way valve block. It was flipped 180°. *raises eyebrow* Does this indicate a different model than what’s shown in the manual?
Nope! Removing the valve block shows that this flipped orientation totally blocks the fluid from being able to pass through to the turn rams. The holes just won’t line up. Well well well, how about that...
Not only does that keep the turn rams from turning the plow side-to-side, but in order for the lift ram to operate, fluid needs to pass through that valve block first.
After passing through the “Hydra-Turn” 4-way valve, fluid meets the 3-way valve. If that valve is in the proper position, the lift ram should operate. Unfortunately, the backwards 4-way valve wasn’t the only thing keeping the lift ram from moving. The 3-way valve was completely out of adjustment. A little too loose here, a little too tight over there, and one of the O-rings was all chewed to hell.
I disassembled all the valve assemblies, down to every last spring and ball, and found one of the valves in the 4-way block seized up due to the parts being stacked in an improper order. Fortunately, I was able to get it unstuck, and made sure that it could be put back together without hanging up again.
But this thing needed more than just a rebuild kit. The lift ram itself was all pitted, and was bound to chew up any brand—new packings that I installed. (not to mention leak...)
So I contacted my neighbor, confirming his suspicions that the ram would have to be replaced. He ordered up some new parts and sent them my way.
I cleaned up the housing of loose paint, and once the parts came in, I was so excited to get it back together that I totally forgot to take any more pictures. I cleaned everything up, installed new seals and gaskets, replaced the ram and its packings, and reassembled the unit, taking special care to make sure that it was adjusted properly this time.
Of course, before turning it back over to my neighbor, I hooked up some 12V power and confirmed operation. I was only able to move the lift ram, since he had the turn rams and hoses over at his place, but I knew that if he did end up having any problems (he didn’t, BTW), at least the hydraulic unit wouldn’t be the source of the issue.
Sorry I don’t have any pics of the finished product, but here’s some more from the rebuild process: