M1084 crane hydraulic troubleshooting

[Suprman]

Been working on my m1084. I can lower the outriggers and the safety sensors release the upper control bank. Then I have rotation control, cable in and out and very slow boom out. The boom comes in normal though. I don’t have any boom up function. Mast up and down is on the lower bank and that works ok. I have the troubleshooting manuals they don’t seem to get control specific. It says notify ds maintenance. Anyone had a similar issue?
Will

 

[SausageGuy]

Not that exact problem but while troubleshooting mine today noticed on Hyd schematic foldouts they list GPM for different circuits. Might help. Got my cable to come down finally today. Crane has been stuck up for 3 weeks since first time got any of it to move. Cable brake hoses release and service had been crossed. It would only go up. Also if fluid is leaking drastically past your seal it would slow down as well. Seal could be rolled on boom out. Does motor bog down when you try some of the functions you are having trouble with? That is how I figured out mine was in a bind.

 

[Andyrv6av8r]

Been working on my m1084. I can lower the outriggers and the safety sensors release the upper control bank. Then I have rotation control, cable in and out and very slow boom out. The boom comes in normal though. I don’t have any boom up function. Mast up and down is on the lower bank and that works ok. I have the troubleshooting manuals they don’t seem to get control specific. It says notify ds maintenance. Anyone had a similar issue?
Will

Make sure that you Mast up to the full extension, like vertical. It seems like I encountered the same issue once with RMTaunton's and it worked.

 

[Suprman]

i can try to mast up further. It will hit the control box if you go too far. It’s just odd that some of the functions work.

 

[Suprman]

I wanted to try the bypass. Could not get it to move. Tried tapping it in with a mallet. No luck. Tried a big prybar between that and the tail light bracket. No luck either.

 

[Andyrv6av8r]

Are you actually putting weight on the outriggers?

 

[Suprman]

The outriggers go down I have the square pads. I do it till the truck comes up slightly in the back take the load off the tires.

 

[Suprman]

Took apart the bypass control. Cleaned up nice and it moves now but no change in symptoms.

 

[SausageGuy]

If you have the correct flow from that valve sounds like one side of the cylinder seal is torn or rolled.
You can switch hoses and see if problem moves or it is still in same place.(valve handle will be backward)

 

[Suprman]

I am beginning to think I don’t have enough flow to the upper bank of hydraulic controls.

 

[8madjack]

Subbed, I have a crane, I plan to put it on my m931a1. The only info I have is from the mtv tms, do you have seperate troubleshooting manuals? I'd be interested in case I run into issues when I finally mount it and start messing with it. Thanks.

 

[Suprman]

There is basic troubleshooting. Alot of stuff says to notify higher level maintenance. I dont have the hyd flow testing equipment anyways. Theres a local hyd shop I have used in the past to rebuild cylinders. I might take it over to them see what they think. I spoke with one of the local unit guys I know. He said they had a similar problem on a hemtt crane and after going thru the whole thing it ended up being a weak pto pump. There is a filter on the tank I need to order one and replace that see if it helps.

 

[8madjack]

Gotcha, yea I hate the references to higher level maintenance and then there's no higher level TMs. I saw the crane work before it was removed from the donor truck, I'm just thinking ahead and like to have all the knowledge and resources I can.

 

[firefinder]

Suprman,

Any updates on your crane troubleshooting?

 

[Suprman]

No. I will take it to my local hyd shop. Unless I can see a physical issue I am not good at hyd troubleshooting. I don’t have a flow tester.

 

[Godspeed131]

Hey @Suprman I know this has been a while but I just got a m1084 last week and my crane is doing the exact same thing as this. Wondering if you ever figured this all out or not, so I could possibly be headed in the right direction.

 

[Suprman]

Yes. The outrigger down sensors werent working so the upper bank was in protection. You can unplug the lockout solenoids and the crane should work.

 

[Godspeed131]

Where are the lockout solenoids located, I’m just getting familiar with this crane and the locations on everything.

is it the two solenoids attached on top of the upper bank, one above the left two controls and one above the right two controls?

 

[Suprman]

On the hyd manifold. There are control solenoids on the valves themselves and lockouts on the manifold body. There is a main feed behind the manifold with a lockout on it too. Did you try putting the outriggers down farther?

 

[Godspeed131]

Yea I tried different heights, even fully extended. I do know the main lockout works as far as I know cause without the outriggers down nothing works but as soon as there down with weight every thing unlocks but the main boom will not budge.......I unplugged the lockout solenoids and the cable hoist feed speed has increased and my telescoping in and out has increased but the boom still will not raise. Also before I unplugged the lockouts I did notice the boom spool had a bypassing sound unless I messed with the mast controls then the boom handle would bounce and stop bypassing, thinking that maybe my issue is the actual spool itself possibly. With the lockouts unplugged I never had the bypassing sound with the boom spool