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Fisher Mc 10' on 05 GMC 4500 turns slow!!!!

Discussion in 'Truck & Equipment Repair' started by tjcezar, Jan 3, 2009.

  1. tjcezar

    tjcezar Member
    Messages: 63

    I put a used 10' Fisher MC plow on my GMC 4500 and everything seems to work ok except when I turn the plow left it moves slow and then stops pre-maturely. If I hit the button left again it will move slowly till it is fully turned. I drained the fluids and put in new fluid (S.A.M. fluid was what I has available). The old fluid was thick and milky. It almost seams as if there is air in the line but wouldn't that work its way out after a couple tries? Any suggestions would greatly be appreciated.:help::help:
  2. mr.muddmotors

    mr.muddmotors Junior Member
    Messages: 28

    thick milky fluid is usually an indication of water intrusion somewhere in the system. possibly it was freezing inside the left angle cylinder not allowing all of the fluid to pass back through the line. did flushing the system help your issue?
  3. tjcezar

    tjcezar Member
    Messages: 63

    Not really. It may be a little quicker but is still slow left.
  4. gary42095

    gary42095 Member
    Messages: 45

    blue fluid? regardless... milky is water. water freezes and clogs up the screens. it is not too hard to clean. but you mave have to take the whole pump off the plow frame to pull the resivoir off. four small bolts (5/32nds) i think . after you drain res..... pull res down and there will be a pickup tube with a screen on it... pull it off and clean it out... brake cleaner and compressed air work well. and do the same with the other filter/screens in there. (not sure how many on that pump) you could have crud blocking it as well as water frozen... are your angle pistons straight? look closely... i had a bent tube on one of my angle pistons and it did a similar thing.

    it may be a pain to do but if you pull the hoses off the pump, for the angle pistons. (put them in a pail as fluid will squirt) and manually move the plow (while it is in the air obviously) and see if it is binding up.
    water can be getting in from leaking piston seals (if oil is leaking water can get in)
    where the pump and electric motor mate there is a gasket.

    look at part # 29 and 22/24 in the pic for screens and if # 44 on your is metal go and buy the plastic one.
    http://www.fisherplows.com/posters/poster.asp just cut paste link... and go to hydraulic units on the right hand side..... your pump should be the one on the left after clicking
    Last edited: Jan 4, 2009
  5. tjcezar

    tjcezar Member
    Messages: 63

    Thanks! I will take a look tomorrow. Hopefully that is it. At a quick look the cylinder did not look bent but I will check again.