MACKS Posted August 4, 2015 Share Posted August 4, 2015 Its a side mount pto and Munchi hyd pump mounted to a Mack 12 speed.problem is all of sudden the body wont stay up loaded or empty,goes up fine but then slowly come right back down,the directional valve is moving freely back and forth when i move the lever,its air operated,thinking theres dirt or something stuck some where,but where,can i take something apart and clean it or should i take the pump off and bring it somewhere to be fixed,got to get back up asap,thanks for any help Quote Link to comment Share on other sites More sharing options...
hatcity Posted August 4, 2015 Share Posted August 4, 2015 A) the packings in the piston are bad, causing it to leak back the directional valve is got something keeping it open and holdingEither way, make DAMN WELL SURE you prop the body before going under Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment Share on other sites More sharing options...
MACKS Posted August 4, 2015 Author Share Posted August 4, 2015 A) the packings in the piston are bad, causing it to leak back the directional valve is got something keeping it open and holdingEither way, make DAMN WELL SURE you prop the body before going underIm sure its not the piston and the valve is closing all the way,i went under and taped it in the make sure,could there be something wrong with it like o ring or something,seems like its just not shuting of the flow. Quote Link to comment Share on other sites More sharing options...
hatcity Posted August 4, 2015 Share Posted August 4, 2015 should have asked-is it a telescopic piston or single stage?IF single, then like I said the packing may be shot.have you brought it down, stop, and see if it still drops?stupid question-hyd oil level good? Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment Share on other sites More sharing options...
MACKS Posted August 5, 2015 Author Share Posted August 5, 2015 Its a telescopic,let it down and tried to stop it but it just slows it down,it comes down normal if i put it in hold or up position it just comes down slowly. Quote Link to comment Share on other sites More sharing options...
keg1 Posted August 5, 2015 Share Posted August 5, 2015 My dump trailer did the same thing for awhile and I didn't know where to look for a problem and one day it started working like it should. I figured it must have had apiece of dirt somewhere. Good luck Quote Link to comment Share on other sites More sharing options...
MACKS Posted August 5, 2015 Author Share Posted August 5, 2015 My dump trailer did the same thing for awhile and I didn't know where to look for a problem and one day it started working like it should. I figured it must have had apiece of dirt somewhere. Good luckexactly my thought but where and how do i get to it to clean it,if i wasn't hauling asphalt i could let it go. Quote Link to comment Share on other sites More sharing options...
gearhead204 Posted August 5, 2015 Share Posted August 5, 2015 i think you will have to remove the selector valve and see whats going on, it might be a broken centering spring if it was other debris in the system i wouldnt think it would lower. because the center spool land couldnt go past center. Quote Link to comment Share on other sites More sharing options...
MACKS Posted August 6, 2015 Author Share Posted August 6, 2015 Drained it out and dropped the pump,took out the selector valve and clean it and inside and also the pressure valve blew everything out with compressed air and also clean out hyd tank and re installed with new hyd fluid,same problem,so tomorrow I'll get a new pump and be done with it.. Quote Link to comment Share on other sites More sharing options...
MACKS Posted August 6, 2015 Author Share Posted August 6, 2015 Gave it one more shot and pulled out the entire relief valve cartridge witch I didn't do before and found the problem,a little piece of metal stuck in there,back up and working perfectly. .Sent from my SM-G900V using Tapatalk Quote Link to comment Share on other sites More sharing options...
MACKS Posted August 6, 2015 Author Share Posted August 6, 2015 No filter,my fuel tank was converted to a hyd tank when i added a drop axle,thats where that piece of aluminum came from,I took the tank off and flushed it out good added all new hyd fluid,400 bucks just for the hyd fluid,nothing is cheap any more..lol Quote Link to comment Share on other sites More sharing options...
41chevy Posted August 6, 2015 Share Posted August 6, 2015 I would still find a spot for a filter. It'll save you dollars and grief in the long run. Quote "OPERTUNITY IS MISSED BY MOST PEOPLE BECAUSE IT IS DRESSED IN OVERALLS AND LOOKS LIKE WORK" Thomas Edison “Life’s journey is not to arrive at the grave safely, in a well preserved body, but rather to skid in sideways, totally worn out, shouting ‘Holy shit, what a ride!’” P.T.CHESHIRE Link to comment Share on other sites More sharing options...
MACKS Posted August 6, 2015 Author Share Posted August 6, 2015 I would still find a spot for a filter. It'll save you dollars and grief in the long run.That would be nice but I dont think there's enough room,never had a filter on any of my other dumps and no problems,see how it goes,so if any one has a similar problem you know where to look first. Quote Link to comment Share on other sites More sharing options...
Maxville Truck Posted August 10, 2015 Share Posted August 10, 2015 Set it up as a 3 line system.... there is a sleeve that goes in behind the suction fitting, when making the conversion then the "3rd" line is added, then u can put a filter on the 3rd line back to tank... or leave it... Quote Link to comment Share on other sites More sharing options...
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