M1084 crane wont telescope in

Tatted63M

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Hey everyone,
Been on this site all summer reading your guys post and everything that's been done to your trucks, so cool.
Just bought a 2000 M1084. I used the crane to lift some things in the bed and everything was good. I went to stow the crane and I telescoped in I heard a knock. After that, all functions worked except the telescope in. Has anyone ran into this problem? I figured I might have tripped some safety feature and thought there might be a way to reset. Checked the TMs but didn't find anything for troubleshooting of the crane just one procedure for OVERLOAD SHUTDOWN SYSTEM. Anything you guys can help with is much appreciated
 

simp5782

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Did you hold in the manual override button while trying to retract?
 
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simp5782

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Mine seems to be really stuck, I was not able to push it in. Will that fix the problem or just stow it till I can fix it?
If it's an electronic safety that Is causing it to not close then yes it will help.

If the cylinder is having issues you can remove the hoses going to it and try to retract it with a come along

You can always put the boom over the bed and retract your outriggers so you can move it around and so you can work on it
 

Tatted63M

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Any tips to unstick the override button? I tried spraying it and tapping it but no luck. And thanks for the tips. I currently have it over the bed with outriggers up but I need to retract the boom to lift my toolbox out. It's close to 3500 pounds so I can't have it extended that much
 

simp5782

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Any tips to unstick the override button? I tried spraying it and tapping it but no luck. And thanks for the tips. I currently have it over the bed with outriggers up but I need to retract the boom to lift my toolbox out. It's close to 3500 pounds so I can't have it extended that much
You should be able to just jump the circuit on the back of it..

Use the winch to lift things not the boom. Even with it extended go up high and use your cable then swing it off. If you box is at the back of the truck then use the cable to slide it up front. That crane will handle that weight all the way out. Then hydraulic lift will go into bypass at that weight but the winch should still pull.

The winch is much stronger than the hydraulic lifts. People make this mistake on the 5 Ton wreckers alot.
 

Tatted63M

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You should be able to just jump the circuit on the back of it..

Use the winch to lift things not the boom. Even with it extended go up high and use your cable then swing it off. If you box is at the back of the truck then use the cable to slide it up front. That crane will handle that weight all the way out. Then hydraulic lift will go into bypass at that weight but the winch should still pull.

The winch is much stronger than the hydraulic lifts. People make this mistake on the 5 Ton wreckers alot.
Ok I'll try the jumper. Thanks for the tips. I did use the winch to lift it into the truck no problem, didn't try to extend with it though. Didn't think it could hold that much weight all the way extended, according to the load chart
 

Tatted63M

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You should be able to just jump the circuit on the back of it..

Use the winch to lift things not the boom. Even with it extended go up high and use your cable then swing it off. If you box is at the back of the truck then use the cable to slide it up front. That crane will handle that weight all the way out. Then hydraulic lift will go into bypass at that weight but the winch should still pull.

The winch is much stronger than the hydraulic lifts. People make this mistake on the 5 Ton wreckers alot.
I was able to get the override switch to work. Got all the functions to work except the retract of the boom. Is it possible to use to the hand pump to telescope it in?
 

simp5782

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Donyou
I was able to get the override switch to work. Got all the functions to work except the retract of the boom. Is it possible to use to the hand pump to telescope it in?
Do you hear any fluid trying to bypass when you move the control? Or see the hoses going to it jumping like it's trying to move?
 

Tatted63M

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Donyou


Do you hear any fluid trying to bypass when you move the control? Or see the hoses going to it jumping like it's trying to move?
I can hear fluid flowing through. It sounds like it wants to start working but nothing moves. I tried to push on it a lil while holding the lever. I can't see the hoses flex though
 

simp5782

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I can hear fluid flowing through. It sounds like it wants to start working but nothing moves. I tried to push on it a lil while holding the lever. I can't see the hoses flex though
Check and see if there is a pin safety on that boom insert along the main boom. It may have a lever that locks down when it gets too far to not let it go anymore but then didn't release to let it come back in.

I've seen it on a 1084A1 and a another grove variant crane.where it had a lever inside the beam.
Or post a picture of your main beam on both sides please.
 

Tatted63M

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Check and see if there is a pin safety on that boom insert along the main boom. It may have a lever that locks down when it gets too far to not let it go anymore but then didn't release to let it come back in.

I've seen it on a 1084A1 and a another grove variant crane.where it had a lever inside the beam.
Or post a picture of your main beam on both sides please.
I didn't see any lever unless I missed it? Here are some side views
 

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NDT

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Isn't there something on these that locks out functions if the outriggers are not down properly?
 

simp5782

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Isn't there something on these that locks out functions if the outriggers are not down properly?
Yes but the override should bypass that.
Especially if the line is jumping and fluid is going thru the valve when it is moved.

Next step I would remove the lines going to the linear cylinder and see if there is pressure to it when the lever is pressed. If so then I would suspect the pin broke and go from there if there is no fluid getting up then I would venture back into the system below
 

Tatted63M

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Yes but the override should bypass that.
Especially if the line is jumping and fluid is going thru the valve when it is moved.

I wonder if the pin in the linear step broke when he heard the knock
Where would I look for this pin? Or is it inside the boom
 

simp5782

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Where would I look for this pin? Or is it inside the boom
Inside the boom. The two bolts on that last mast is where it hooks into. #9 in the one picture


Rear pins are shown as well. I wouldn't suspect them since the lines didn't move when the cylinder retracted or attempted to.

I would start with the lines first to see if there is pressure going up.

These cranes are Similar to the MHC977 model crane used on the M977 and 985s.
 

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Suprman

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There are lock outs on each function. If it’s electronically locked out you can unplug the lockout and it should work. On the boom is a box with cable going out as the boom extends. Thats the load moment control it decides if you have the crane over loaded and will stop it if it thinks you are doing something unsafe. You can also try to move the cable back to the box it just unhooks from the boom arm.
 

Tatted63M

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There are lock outs on each function. If it’s electronically locked out you can unplug the lockout and it should work. On the boom is a box with cable going out as the boom extends. Thats the load moment control it decides if you have the crane over loaded and will stop it if it thinks you are doing something unsafe. You can also try to move the cable back to the box it just unhooks from the boom arm.
Where can I find the lock out for that function? I tried moving the cable at different positions with no movement
 

Suprman

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On the manifold there are connector blocks you can unscrew. The ones on the actual control valves are for remote control functions. The ones on the manifold itself and there is a main lockout behind the upper bank are lockouts. It’s possible the lockout solenoid is stuck too.
 

Tatted63M

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Hey everyone, sorry I haven't replied in a while. Life caught up and haven't had time to work on it. I did try some test on it though. Thinking it had something to do with the 4 way valve I tested that first. I took the 2 telescope lines off and swapped them with the 2 turret swing lines. When I moved my telescope lever the boom swung in both directions and when I used my swing lever the boom didn't telescope. So I figured it has to be the cylinder or the holding valve on the cylinder? Anyone have any suggestions? Been trying to look for a holding valve and seal kit for the cylinder
 
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