aleigh
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I think tomorrow I'll rig it up and crack the lines and I guess we'll just see. And then I'll rebuild the manifold.
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Coolant Took A Vacation
- Thread starter aleigh
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Looking at the diagram there seems to be a small filter in there. Could be clogged.
aleigh
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On the upside, this was a great opportunity to fix my throttle return spring and adjust the slack out of my throttle cable. Maybe my pedal will stop sticking down now...
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I have a 1078A1 that the cab got stuck in the up position as well and tried similar things as you have Note: this happened after I rebuilt the pump. If I recall I read somewhere that the cylinder has a lock valve that comes into play when the cylinder is extended or retracted in a quick manner such like in a crash or something preventing it from moving anymore. But it did not explain how to undo it once this occurs. Mine finally started working after switching the cab valve bake and forth from up to down and using the manual pump handle to build up pressure each time before switching. I thought I was never going to get it down and then suddenly it started working again.
Good luck
Good luck
coachgeo
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For Clarity is this what your saying?
starting with a cab stuck up:
pump switch set to UP mode ... pump a few times......
Set switch to DOWN mode..... pump it down till it stopped lowering.....
then switch to UP mode again, repeat all above from the new stuck cab height
keep repeating steps above till it finally makes it all the way down
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What I did. With the cab stuck in the up position.
Using the manual pump.
Switch in up mode, pump until pressure built up. No movement in the cab position.
Switch to down mode, pump until pressure built up. No movement in the cab position.
Repeat and repeat and repeat until I was red face with frustration.
Give up come back later. Repeat and repeat and........... then suddenly it started working. and has ever sense.
Using the manual pump.
Switch in up mode, pump until pressure built up. No movement in the cab position.
Switch to down mode, pump until pressure built up. No movement in the cab position.
Repeat and repeat and repeat until I was red face with frustration.
Give up come back later. Repeat and repeat and........... then suddenly it started working. and has ever sense.
aleigh
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All these intermittent I-jiggled-the-valves-a-lot-and-then-it-worked stories sound more and more like contamination or debris in the system.
So I have a helper coming today and we're going to rig the cab in case it tries to fall and then crack the low-side return line and then pump it to raise it (I think I'm better off getting it all the way up since it's almost there). In theory if the blockage is in the hydro panel, it'll spray fluid everywhere (instead of returning through the manifold) and raise. And then I can take it all apart.
I've since learned that there's something called a hydraulic fuse which is like a rate limiter for fluid. They are often built into the rams so that if you blow a hose it does not drop the load unexpectedly, rather, sets it down at some rate. They seem to be auto-resetting in most cases but there is another kind where there is a lever deal to reset it. No indication we have anything like the latter on these trucks. So in theory if the rams have fuses it should fall at some "safe" rate even without back-pressure in the system to meter the rate. But we'll rig just in case and and I guess we'll see.
It might be tempting to think there is a fuse in the ram and that is what is causing the problem, but, I have the same problem on all the circuits...
So I have a helper coming today and we're going to rig the cab in case it tries to fall and then crack the low-side return line and then pump it to raise it (I think I'm better off getting it all the way up since it's almost there). In theory if the blockage is in the hydro panel, it'll spray fluid everywhere (instead of returning through the manifold) and raise. And then I can take it all apart.
I've since learned that there's something called a hydraulic fuse which is like a rate limiter for fluid. They are often built into the rams so that if you blow a hose it does not drop the load unexpectedly, rather, sets it down at some rate. They seem to be auto-resetting in most cases but there is another kind where there is a lever deal to reset it. No indication we have anything like the latter on these trucks. So in theory if the rams have fuses it should fall at some "safe" rate even without back-pressure in the system to meter the rate. But we'll rig just in case and and I guess we'll see.
It might be tempting to think there is a fuse in the ram and that is what is causing the problem, but, I have the same problem on all the circuits...
LostInTheWorld
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It wouldn't surprise me if it was contamination. Last weekend we removed the suspension squat actuator hydro system on ours, and when we drained the fluid from the hoses, it looked really milky. After a while, the rate orifices might not do well with funky fluid.
I hope you get yours working soon. That sound a bit frustrating.
Michael
I hope you get yours working soon. That sound a bit frustrating.
Michael
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Funny i noticed an oil leak at my air hydro pump today. guess i'll add a pump rebuild to the to do list, and the list grows....
aleigh
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OK so did as advertised, rigged a winch line to the latch on the cab and then cracked the lines. I opted to do it on the back of the box. The cab lines are the topmost ones so at least that was easy. There wasn't too much pressure when it was all said and done. The cab is settled forward, I think as far as it will go (as far as the ram will extend). I shoved a big metal pole under it on the off chance it tries to fall backwards and kill me but I think that's good enough for now.
So I'll pull the hydro panel off. I'm waffling on rebuilding it myself - I feel like I could do the job after reviewing the TM but there are an awful lot of little o-rings and things. More than half tempted to just take it to a hydraulics valve and pay to have them rebuild it. Figure there's a good chance they'll have most of the little Parker bits and pieces in stock anyways. Any thoughts?
And just in case this thread is worthless without pictures: https://www.flickr.com/photos/adventioneering/albums/72157669897327435
So I'll pull the hydro panel off. I'm waffling on rebuilding it myself - I feel like I could do the job after reviewing the TM but there are an awful lot of little o-rings and things. More than half tempted to just take it to a hydraulics valve and pay to have them rebuild it. Figure there's a good chance they'll have most of the little Parker bits and pieces in stock anyways. Any thoughts?
And just in case this thread is worthless without pictures: https://www.flickr.com/photos/adventioneering/albums/72157669897327435
aleigh
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OK so keeping in mind I had the cab lines disconnected entirely for safety, the crane was still extended and wouldn't go back in. If I selected the cab functions, it would pump hydro out the disconnected port in the back, and was properly choosing the right port for raise/lower. Which still points to a low side problem.
I pulled the 4-way spool (the function select valve) and that caused the crane to fall. But I still couldn't get it back up, the original problem. Pulling the crane valve let me push the crane back into position - the fluid came out of the valve orifice. Which still makes me think low-side problem.
Next up are the check valves.
Also if I didn't expressly say it earlier, the filters were totally clean.
I pulled the 4-way spool (the function select valve) and that caused the crane to fall. But I still couldn't get it back up, the original problem. Pulling the crane valve let me push the crane back into position - the fluid came out of the valve orifice. Which still makes me think low-side problem.
Next up are the check valves.
Also if I didn't expressly say it earlier, the filters were totally clean.
aleigh
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So here we go. Of my 3x 2-way valves, one of them didn't have a good detent. The one for the crane. I think this was also the valve that was leaking, so that will need to be replaced. The other 2-way valves have good solid clicks and turn smoothly so I think they just need the rebuild kits if at all.
The 3-way valve feels weird. Weird enough I'll probably replace it. It has the detents but it also has a gravelly other part of the range which may or may not be normal.
And then the valves... are corroded, and, if I depress the plungers, they feel rough and gravelly. I'm guessing a perfectly new valve feels smooth and good. What surmise I may be happening is they were binding up and not unsticking. This may explain why some people rock the valves enough and it magically comes loose, just to probably happen again on another day. Will try to replace all 3 valves. I can also see what looks like corrosion particles / contamination in the valve orifice for the one that was rusted up the most. Will need to devise some way to clean and flush the manifold itself.
There's a fourth "check valve" that is basically a stopper and a spring. Mine stripped the second I tried to get it out but I was able to get it out with pliers. Needs replacement now though. Be careful with this one.
The part numbers are in the -24P but for posterity:
1x CP valve: Parker CP104PX4879, rebuild kit SK 10-3
2x CV valve: Parker CV101PX4879, rebuild kit SK 10-2
3x Valve, Parker DM104LD1X4879, rebuild kit SK 10-4
1x Valve, Parker DM104LN8X4879, rebuild kit SK 10-4
Will start calling around tomorrow looking for parts. I have no idea about the air side but mine isn't leaking and it's front-service (no need to remove the manifold from the truck) so I'll probably leave that be for now.
The 3-way valve feels weird. Weird enough I'll probably replace it. It has the detents but it also has a gravelly other part of the range which may or may not be normal.
And then the valves... are corroded, and, if I depress the plungers, they feel rough and gravelly. I'm guessing a perfectly new valve feels smooth and good. What surmise I may be happening is they were binding up and not unsticking. This may explain why some people rock the valves enough and it magically comes loose, just to probably happen again on another day. Will try to replace all 3 valves. I can also see what looks like corrosion particles / contamination in the valve orifice for the one that was rusted up the most. Will need to devise some way to clean and flush the manifold itself.
There's a fourth "check valve" that is basically a stopper and a spring. Mine stripped the second I tried to get it out but I was able to get it out with pliers. Needs replacement now though. Be careful with this one.
The part numbers are in the -24P but for posterity:
1x CP valve: Parker CP104PX4879, rebuild kit SK 10-3
2x CV valve: Parker CV101PX4879, rebuild kit SK 10-2
3x Valve, Parker DM104LD1X4879, rebuild kit SK 10-4
1x Valve, Parker DM104LN8X4879, rebuild kit SK 10-4
Will start calling around tomorrow looking for parts. I have no idea about the air side but mine isn't leaking and it's front-service (no need to remove the manifold from the truck) so I'll probably leave that be for now.
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agazza2
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Any update on what fixed the problem? I have the same problem, for the cab lift. If I crack the return line on the cab hydraulic cylinder, it lifts the cab, but you loose hydraulic fluid. Otherwise the cab goes up part way, and then there is pressure that stops the cab from lifting any more. Any update on what you found to resolve this problem would be helpful. Thanks
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Sounds like some type of blockage in the return lines. There may be some type of check valve that opens with a certain amount of pressure.
agazza2
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Aleigh - where you able to locate the valves? I took my manifold completely apart and replace with all new "O" rings.. The only thing I did not disassemble is the pulling the insides out of the selector valves since I could not get the knob to release. The "O" rings where replaced on the selector valves and all the check valves, and fittings at the back. I will be putting together a kit of "O" rings needed for this repair as most of the "O" rings I had to purchase come in bags of 100.
Inside my manifold was very clean, no rust, but the cab still lifts about 1 foot and then has hard pressure on the hand pump or regular pump. if you crack the return side of the hose at the lift cylinder, no fluid comes out. Still seems like there is a check valve stopping the return hydraulic fluid.
Would be nice to locate these valves. Originally I replaced the cab lift two way valve with the suspension valve, and the cab lifted fine, but then it would not go back down all the way. Hydraulic problems are the worst, when you have not done much with hydraulics before
considering switching over to an Electric over hydraulic commercial pump just to feed the cab to avoid this problem in the future if I do not get this resolved soon,
Inside my manifold was very clean, no rust, but the cab still lifts about 1 foot and then has hard pressure on the hand pump or regular pump. if you crack the return side of the hose at the lift cylinder, no fluid comes out. Still seems like there is a check valve stopping the return hydraulic fluid.
Would be nice to locate these valves. Originally I replaced the cab lift two way valve with the suspension valve, and the cab lifted fine, but then it would not go back down all the way. Hydraulic problems are the worst, when you have not done much with hydraulics before
considering switching over to an Electric over hydraulic commercial pump just to feed the cab to avoid this problem in the future if I do not get this resolved soon,
aleigh
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The cartridge valves were made on a military contract with special part numbers. Those literal parts don't seem to be commercially available anymore but what you can do is get like-parts at similar pressure ratings from their commercial product line. The Parker cartridge sizings are standard, so you will see if you look through the catalogs there are many valves available. The simplest thing to do is just take the manifold to an experienced hydraulic ship and dump it there with a puzzled look on your face. Sorry I don't have part numbers for you, my stuff is all up in Seattle. I was able to obtain a new in box military manifold, though, and swapped to that on the truck.
The o-rings - they are available to rebuild the valves in little baggies from parker which come with the 3 or 4 (I forget) different o-rings you need to do an entire spool valve. Parker branded. A hydro shop will know all about this too. I have some in one of my parts bins.
The o-rings - they are available to rebuild the valves in little baggies from parker which come with the 3 or 4 (I forget) different o-rings you need to do an entire spool valve. Parker branded. A hydro shop will know all about this too. I have some in one of my parts bins.
agazza2
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Aleigh,
Thank you. I found the correct sizes of "O" rings at Marting Fluid Power (MFP) and was interested if you ever located the valves. Thanks for answering my question, and suggesting commercial like valves. I will see if MFP can get these. It would be nice to do a full rebuild of these manifolds with off the shelf parts.
Thank you. I found the correct sizes of "O" rings at Marting Fluid Power (MFP) and was interested if you ever located the valves. Thanks for answering my question, and suggesting commercial like valves. I will see if MFP can get these. It would be nice to do a full rebuild of these manifolds with off the shelf parts.
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Thread should be renamed to FMTV/LMTV hydrolifts + coolant so one day it can be found again. Those really good pictures will be hard to find. Those good photos at https://www.flickr.com/photos/advent...57669897327435
will be gone too?
will be gone too?
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CMPPhil
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0818 local
That is one of the problems. The link works good when accessed thru the link in post #30 but these things are hot, like in excel, and do not like being copied to anywhere. That is why I say they are "gone". Maybe they are not "gone" just hiding in there someplace. Neat LMTV hydro pictures though.