j_martell Posted October 1, 2014 Share Posted October 1, 2014 2011 GU813 MP7 with fuller 8ll & Muncie pto....Pump engages normally, reservoir is full, no leaks. When engaged and recirculating it sounds normal, but when using the hydraulics to raise/lower box or cable in/out is sounds and surges like its starving for fluid....Checked all the obvious, ball valve on supply is open, no crushed lines, return pressure gauge reads normal level, but bounces around when using the controls.....Not sure what's next. only thing I can't do is look inside the tank to see if some trash or something got into the suction line. But we've never been in the tank so even that I doubt. Did 2 switches and all was fine, then picking up my empty all of a sudden it startedSorry for the confusing post. Writing it down as I think it Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/ Share on other sites More sharing options...
hatcity Posted October 1, 2014 Share Posted October 1, 2014 filters? Quote Success is only a stones throw away.................................................................for a Palestinian Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261763 Share on other sites More sharing options...
j_martell Posted October 1, 2014 Author Share Posted October 1, 2014 The only filter (that I'm aware of) is on the return line to the tank....it also incorporates a gauge displaying the flow to the tank....which still rides in the "ok" zone when pto in and not using the hydraulics, and flutters around like a drop/surge in return pressure when using the hydraulics, but stays in the green..... Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261769 Share on other sites More sharing options...
mrsmackpaul Posted October 1, 2014 Share Posted October 1, 2014 has the suction hose gone all soft and sucking in on its self ?Paul Quote Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261774 Share on other sites More sharing options...
j_martell Posted October 1, 2014 Author Share Posted October 1, 2014 All the hoses appear ok from the outside. I'm guessing I'd have to take it off and look at the inside? Or would it be obvious just looking at it. It's not starving for fluid constantly, the rails/cable do work, just really jerky....After its fixed I'm gonna put a pressure gauge on the valve body 😡 Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261775 Share on other sites More sharing options...
Kansas farmer Posted October 1, 2014 Share Posted October 1, 2014 Do the lines surge or just the bed? May be there is air in the cylinder we have to bleed our every once in awhile because the bed goes up jerky. If the lines are jerking around I would say hose or suction. May even check the vent to be sure it's not plugged. As far as the lines go they car suck in on themselves and you might not be able to see it the best way is to feel for soft spots in the lines. Quote Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261782 Share on other sites More sharing options...
j_martell Posted October 1, 2014 Author Share Posted October 1, 2014 The lines surge the same time the bed/cable cyl do.....funny you mention the vent. The boss said the same thing, but I didn't get it. I only understand and tested the basics of the system. Would you mind elaborating on the vent thing. I squeeze the lines to and from the pump in a few spots....and they feel like they alway do, but didn't check the whole length of either line Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261783 Share on other sites More sharing options...
Brian Blaylock Posted October 1, 2014 Share Posted October 1, 2014 There should be a vent on your tank a lot of times they have a vented cap to allow it to relieve pressure much like a fuel tank if you cycle the system a time or two then take the cap off and it has pressure that is more than likely your problem 1 Quote Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261786 Share on other sites More sharing options...
85snowdog Posted October 2, 2014 Share Posted October 2, 2014 Brian has it covered, but to add a little more, I think the basic concept of the vent j_martell is, as the oil leaves the reservoir to fill the lift cylinders, it has to be replaced by air. If air can't get in the reservoir , oil won't be able to easily leave, creating a vacuum in the tank. A good spot to checkAlso , might sound stupid but your oil level is right? were you loading uphill or downhill, and the oil supply line on the high side of your tank. Quote Keith Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261787 Share on other sites More sharing options...
j_martell Posted October 2, 2014 Author Share Posted October 2, 2014 From reading the above posts, it think the vent is ok.....tried it from the cab, funny noise....stop. Get out and look, run from outside watching and listening for leaks, check level, it's okay. Pump off and crawl underneath, no leaks/wetspots, went to take off the cap to look inside forgetting there's a screen in the filler, but no rush of air in or out. As soon as I hit send on the post asking for clarification it hit me like a tonne of bricks why the vent would cause trouble, an "oh.....right...duh" moment for sureKeith; fluid level sight glass is in the top 1/4 of the tank, and read halfway on the gauge, and just to be sure the level was accurate, I let the rails fall pump off about 8" and watched the level rise....load was in a level paved lot, and the pump suction line is a 2"(?) 90* to soft line from the bottom center of the tank. a few weeks ago the guy I work with tossed the hook in the frame the wrong way, and it knocked the hard line 90* fitting loose on my cable out side.....thats the only hydraulic repair/trouble I've had in 150,000kms...... 1 Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261798 Share on other sites More sharing options...
85snowdog Posted October 2, 2014 Share Posted October 2, 2014 like a good operator, looks like you have all the basics covered. Looks like you might have to dig deeper. Hope you can get it figured out. Sorry i can't offer any advice.Keith 1 Quote Keith Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-261801 Share on other sites More sharing options...
j_martell Posted October 5, 2014 Author Share Posted October 5, 2014 Ah F***....forgot to update......Boss man said he'd check it out that night, and low and behold, no trouble.....he cleaned the vent but didn't think that was the problem....wasn't stuck or anything. I told him when I took off the cap there was no trapped pressure....so we're all at a loss as to what the problem was.....next rain day were gonna book it into the shop and have them check it out, though I'd rather do it myself, they think our local mack dealer should deal with it....Ran fine the rest of the week, including one "slightly" heavy load from another roofing company that we rent bins to...truck was hanging the front end picking it up with 90% of the bin on the truck....get to the transfer station and the guy in scale house asked how the ride was to all who offered help, thanks....i thought I had done what I could, just wanted to make sure I hadn't overlooked anything simple.... Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-262179 Share on other sites More sharing options...
j hancock Posted October 5, 2014 Share Posted October 5, 2014 Let us know.Hmmmm....the fill line on a bin is the top edge plus a little...? Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-262186 Share on other sites More sharing options...
Lmackattack Posted October 5, 2014 Share Posted October 5, 2014 Another thing to check is to make sure the hose connection between truck and trailer is good. One time I did not have the hose end screws down all, the way and the bed was slow to go up and down.. Just another thought... Quote Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-262203 Share on other sites More sharing options...
mrsmackpaul Posted October 5, 2014 Share Posted October 5, 2014 sometimes a hose can seperate on the inside and while the out side looks fine the inside can collapse and close off BUT !!!!!!! it would only be the suction hose from the tank to the pump that could cause your problem are you sure there is not a piece of plastic floating around in the tank that drifts over the pickup every now and then because one way or another when this happens you pump is getting starved for oil so it should be pretty easy to find maybe there is some poxy filter on the suction in the tank that has collapsed ?Paul 1 Quote Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-262207 Share on other sites More sharing options...
j_martell Posted October 5, 2014 Author Share Posted October 5, 2014 Fill line?!?! That's funny!! Roofers don't care, they just dump wheelbarrows in the same spot all day, then I get to sort it out to haul it......plus picking up the stuff on the ground, just one of the many reasons I asked to go back to hauling with the vacuum...but I will say that this comoany we rent too is pretty good at leveling it out before i get there, because it cost them money to have me fix it to tarp and haul it.This was a re-sat (re-saturated or over-pour roof) where the existing roof was re-saturated with asphalt and gravel to give another 10yrs of life from an otherwise beat roof.....making the roof mat twice as thick and twice as heavy....like two tear offs in one bin, minus the extra insulation, which in this case was soaking wet fibre board, again adding to the weight.No trailer here Lmackattack, just a roll off truck, but thanks for the input Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-262208 Share on other sites More sharing options...
j_martell Posted October 5, 2014 Author Share Posted October 5, 2014 sometimes a hose can seperate on the inside and while the out side looks fine the inside can collapse and close off BUT !!!!!!! it would only be the suction hose from the tank to the pump that could cause your problem are you sure there is not a piece of plastic floating around in the tank that drifts over the pickup every now and then because one way or another when this happens you pump is getting starved for oil so it should be pretty easy to find maybe there is some poxy filter on the suction in the tank that has collapsed ?Pauli doubt it about the plastic in the tank, weve never been in there and theres a strainer in the filler, and its only ever happend that once and not since my oringinal post.....ill undate when it goes to the shop and what they find.....but with their current track record, im betting on nothing..... Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-262210 Share on other sites More sharing options...
j_martell Posted December 1, 2014 Author Share Posted December 1, 2014 update: It did it again in the yard a few weeks ago. this time the boss said take it to the dealer after he and I farted around with it in the yard for about an hour. Mack had it a few days and finally got back to me saying they replaced some line (guy on the phone sits at a desk) and it was working fine. Got it back and same shit again, right off the hop. Took it back and said its not fixed....fix it again. tried it in their yard and low and behold it worked, still left it there and told them the boss authorized removing/replacing the PTO/pump. sure as shit, the shaft from the PTO to the pump was stripped....and would catch and work fine for a bit, then start slipping again. so 4 days, new pump, new PTO, new suction line, other driver goes to pick it up as i was away, tries it in their yard again, no go......shit hit the fan.....its now been over a week....i go back to get it on tuesday, and ask the mechanic i chat with what happened the last time, he says "the suction line ball valve was left closed from the pump replacement....." tried it in their yard, and all is good.....been good all week...and there's shiny new parts on my (until next friday) rig:) Quote Lack of planning on your part does not constitute an emergency on my part.... Link to comment https://www.bigmacktrucks.com/topic/37238-pto-trouble/#findComment-268771 Share on other sites More sharing options...
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