My dad has a JD 310B & the other day it busted a line. He had the line repaired and put it back on, started it up & nothing would work (no forward-no reverse-no backhoe or loader movement) he let it run a little more and it busted the metal line again. It's like its building up to much pressure. I checked screen & it was clean, I replaced both filters, repaired line. Still nothing, I'm afraid to let it run too long cause it will probably bust another line, but nothing will work. Can anybody help. It's seems to me like it might not be flowing the hydraulics correctly & maybe not returning fluid & has to much pressure for lines and nothing will work.
Which line? Pictures if you can, those old Deeres are a plumber's nightmare. The hydraulic pump gets it's oil from the transmission pump, if the transmission has no forward or reverse, the problem is before the hydraulic system. There's a transmission relief valve in the case I think just above the plug for the suction screen, but having too much pressure probably wouldn't stop the transmission from engaging, at least until something else blew out, like piston seals inside the tranny.
It is the pressure line from the pump i think. My dad couldn't get it off when it blew so he cut it. He got the part that blew fixed and put a compression fitting where he cut it. When we start it still no forward/reverse or any backhoe or loader functions then after a minute or so of running it blows the compression connection apart.
Line # 11B in the diagram We had to tow it home, it is at my garage now. I am auto mechanic but not much experience on backhoes
There aren't many common tubing compression fittings that can handle a few thousand PSI. The pressure rating goes down as the tubing size increases. Tell us what compression fitting & size was used.
I think it is about a 1/2" steel line. I told my dad i didn't think it could hold the pressure. But when i start the backhoe and before the line blows it still wont move & no hydraulics. I am going to get the line welded back together but i pretty sure i have a problem other than that
How about taking that line to a hydraulic shop and getting a new one made? Rather than wasting time, money, and oil again.
The only thing that could create high pressure there is the stroke control valve in the pump head is malfunctioning. This system operates at full max pressure all the time and the stroke control valve regulates that pressure. Still, I think the pressure control valve which is ghosted in at the end of that steel line, should dump pressure if it's too high but I won't swear to that, it's been thirty years. That should not affect the transmission though, need to check what you're getting on the inlet side of the hydraulic pump as that comes from the transmission.
After rereading, the fact you still don't have any loader or backhoe hydraulics is a mystery, how can you blow a steel pressure line off the pump if there's no pressure to the control valves? The pressure control valve may be the culprit going on that symptom, but then the transmission issue is still odd.
Yair . . . "Swagelock" fittings are designed specifically for very high pressure and I have never seen one fail. Cheers.
I'm having the same problem minus the line breaking.
How many gallon of oil did you have to add to the system.