# So how do I change the HYD fluid on my belt driven Fisher plow system?



## Zack1978 (Apr 30, 2005)

Hello,
If you have read any of my other posts, I own a 1979 Toyota 4x4 p/u, with a Fisher plow (circa 1979 or 1980). Well the the truck is new to me, and I want to change/flush out the hyd fluid. I guess that is the only maint I need to do to the plow setup?? So my question is how do I change the hyd fluid? The HYD pump is belt driven, and it looks like a big coffee can under the hood. The fluid is red in color, I guess as it is auto trans fluid. So what is the best way to change the fluid? Do you have any other tips, as to things that I should do to the plow setup? Should I take the belt off the pump for the summer so that the pump does snot have to turn? Also what type of auto trans fluid should I put in my plow setup? There are so many types of fluid out there, what is the best, dextron, mecron, etc? And how much fluid should I put in the pump tank?

Thank you,
Zack


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## calhoun (Oct 18, 2003)

I disconnect the return hose (low pressure hose from valve body to pump) and put it into a drain pan. Cycle the plow though all its motions. Notice the color of the old fluid draining out with every cycle. Keep adding new fluid until you see it coming out the return line instead of the old.
The pump is on an electric clutch (like an AC clutch) and only engages when needed. No need to remove the belt.
I use Dextron II.


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## karl klein (Jan 28, 2001)

i don't know if you have had any problems with the atf fluid but my old boss would always freeze up at the quick couplers there was probably some moisture in it but i switched it over to the blue hydralic fluid


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## calhoun (Oct 18, 2003)

karl klein said:


> i don't know if you have had any problems with the atf fluid but my old boss would always freeze up at the quick couplers there was probably some moisture in it but i switched it over to the blue hydralic fluid


Funny you should mention that. I never thought about the fluid but did have lots of trouble with the connections. So much that I will never get an engine driven hydrolic again (I don't think they are made anymore anyway). I always thought it was because of the ice that always covered them. From day one if there was an ice storm I had to fight with the plow. I wish I had your post 8 years ago I would have drained out the stuff that fisher put in it and replaced with the blue maybe saved lots of cursing. Thanks for the tip.


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## karl klein (Jan 28, 2001)

yea they still make them on the larger plows. they would only freeze up periodicly and the plow wouldn't angle i would have to fight to uncouple the connections becuase of the force that the pump put on the connection in then slam the male end against the bumper and make a good mess so i thought it was the quick connects and i replaced them the next day. it did it again about a month later i noticed it was really cold and looked at the fluid on my bumper and i could see little ice chunks. that is when i realized the fluid was freezing up.


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## Zack1978 (Apr 30, 2005)

Thank you for the excellent answers. To change the fluid, how about taking the hose off the main lift ram, than operating the plow ram up and down to drain the fluid? I assume I can not let the res run dry? Should I refill the res to the brim with fluid? Right now I am going to stick to normal ATF fluid, but in the winter I might change it again. So what is the exact type of atf to use, there are at leat 5 different types of atf at the auto parts store. Can I switch to the blue fluid after all these years with normal atf?

Thanks,
Zack


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## karl klein (Jan 28, 2001)

i would change over to the blue fluid now why change it twice if you don't need to mine cost me about 3.50 a quart so not much more then atf. plus the blue fluid has a conditioner for the seals.


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