BPI square shooter main boom bleeding out

[CarpenterCory]

Purchased a heavily used BPI square shooter SS-836. It's served me well for its age (1992) but I began having problems with the main boom slowly bleeding out constantly. If the boom is lowered to the ground it will bleed out even when the machine is running or shut off. If its running it stops after you lift the boom to a certain height, so gravity is certainly affecting it. I am not a great mechanic, and an even worse diesel mechanic. I feel like it's a bad valve, stuck open or something? But honestly this thing is like a frankenstein. There are control valves and hoses running everywhere. Just looking for a couple of ideas of where to even start troubleshooting it. Thanks for reading.

 

[Delmer]

Please clarify "bleeding out", is this leaking fluid, or is the cylinder slowly dropping on it's own, or both? Is this one cylinder only?

 

[CarpenterCory]

Also, I'm not opposed to having someone else work on it. BUt I can't get anyone local that I know and somewhat trust to mess with it. And as a rule I hate to take anything to a mechanic I don't know and have no clue what's wrong it. They could tack any extra fees and parts they want on the bill and I couldn't even dispute it.

 

[CarpenterCory]

No it's not leaking fluid, the main boom just slowly creeps out away from the machine nonstop. This particular telehandler is some kind of a chain driven main boom. It does not have a long hydraulic cylinder powering it like others that I have owned in the past.

 

[Delmer]

So the main boom creeps out, like only when you have it pointing downhill I assume? But it won't creep back in, even if you have it pointing up?

What I can find shows a big hydraulic cylinder for the boom extension, with chains, sort of like regular forklift. Can you confirm a cylinder or whatever else powers the boom extension?

http://manuals.gogenielift.com/Parts And Service Manuals/data/Parts/Telehandlers/IO/238228.pdf

page 6 of the manual, page 19 according to the PDF viewer.

If it's just a hydraulic cylinder, it could be as simple as a leaky piston seal, it would extend slowly, but won't retract because it would be acting as a one way cylinder even with the piston completely gone.

 

[CarpenterCory]

The main boom creeps out always, even when it's not running. It is worse when it is pointed down, but it will still creep out even when pointed up to a certain point.
There is a hydraulic cylinder for the boom extension yes. yes it has chains similar to a forklift.
There are a couple other cylinders that leak oil, mainly the one raising and lowering the fork tilt. But I have not seen any noticeable leaks towards the rear of the machine, or around that cylinder that powers the main boom. maybe I need to look more closely.
Also it retracts fine.
Setting trusses when it won't stop creeping out definitely adds an extra degree of difficulty lol

 

[Delmer]

I can't explain it creeping up even with a load. I'd look at the load check valves #2,3,4 on page 33 of the manual, page 56 of the pdf viewer, those should lock the hydraulic fluid from moving except when pressure is applied to move the cylinder. They are standard on any lifting equipment for personal safety. Could be as simple as a bit of trash or broken o ring in one of them.

Also wouldn't hurt to check the control valve spool, especially the end under the little cap on the bottom of the spool. Check the springs and bolt under there.

Looks like a mess of controls and hydraulic logic for the safety of that thing, this could be a MESS to figure out, hope you like a challenge. None of it is terribly hard to inspect if you take it apart one at a time and put it back together just the way it came out. Just a lot to wrap your head around if you want to figure out the logic and diagnose it logically vs taking stuff out to check for issues.

 

[CarpenterCory]

Thanks a bunch for the help. I did find a local dealer that can actually get parts for this dinosaur. I checked the boom cylinder again today for leaks and it is not leaking too badly. There is some seepage there but nothing you wouldn't expect from a machine this old. I will start with the first valves you suggested and go from there.

Note: I was mistaken a couple of posts before this. There IS a long main cylinder under the boom. Previously I had said there wasn't.

Anyone want to buy a vintage telehandler?? lol I'd make them one hell of a deal!

 

[Delmer]

if you were closer, I might be interested. It really isn't likely to be worse than a broken o ring or the cylinder piston seals. The problem is just finding it. You could do some pressure testing while it's operating, that could involve gauges teed into the hydraulic circuits, or it could be as simple as a bungy strap pulling on a hydraulic hose to see it jump with pressure and relax with no pressure. If you want to read up on hydraulics, then we can suggest some manuals that would explain the basics so you could figure out the logic of what's going on, and hopefully narrow it down that way. or just start removing the valves and inspecting, if you want to try, we can suggest the best way to go about it. It's NOT removing a bunch of hoses and putting all the components out on a bench. One little piece at a time, as much as possible.

 

[Txhayseed]

The boom creeps out with machine shut off ? You come back and its pushed out of nesting position is that correct ? If the boom is extending out with the machine off the problem most likely the main extend cylinder is leaking internally and is equalizing the pressure on both sides of the piston. How fast is it creeping out ? Is it slow like over night or can you shut it off and watch it extend ? If you can see it extend while your watching with out starting it use boom retract and see if it stops.. This is not an uncommon issue with reach forks. Its pretty common as they age and seals wear over time.

 

[ForgeAndFixIt]

Purchased a heavily used BPI square shooter SS-836. It's served me well for its age (1992) but I began having problems with the main boom slowly bleeding out constantly. If the boom is lowered to the ground it will bleed out even when the machine is running or shut off. If its running it stops after you lift the boom to a certain height, so gravity is certainly affecting it. I am not a great mechanic, and an even worse diesel mechanic. I feel like it's a bad valve, stuck open or something? But honestly this thing is like a frankenstein. There are control valves and hoses running everywhere. Just looking for a couple of ideas of where to even start troubleshooting it. Thanks for reading.

I am having the same problem, you’re so right about setting trusses. Challenging! Tell me, did you figure out the problem?