I have a 2012 Skytrak 8042. When I'm running the hydraulics, the engine is bogging down and dying. The local JLG mechanic isn't convinced it's the hydraulic pump. Any thoughts?
Stall test your engine first. The specs you can get from JLG
Checked air/fuel/hyd filters? Service history?
New fuel filter the other day. When the mechanic was out the other day, he got someone from JLG on the phone. The JLG guy seemed to think hydraulic pump. The mechanic thinks it's something in the engine. I asked the mechanic about the hydraulic filter. He said they have a built in by pass and didn't think that would be an issue.
Doesn't bog down in drive?
Nope, it's just fine in drive
Hydraulic pump most likely. Pretty common issue. Done a lot over the years for the same situation. You can tap your gauge into the pressure port on the pump and check to see if pump goes into to relief after a function is activated and released. If pressure stays up and engine stalls out probably time torn down for inspection. Hydraulic pump /function pump is its own suction and flow path. If unit runs fine right up until you command a function then it stalls out and you can restart it just fine with out a drag on the motor the pump is most likely fault. If it does it with all functions and not just one in particular then pump is issue. Pump feeds valve body as a unit and flows return to tank through strainer in tank.
Yeah we tried that and the pressure didn't really drop off too bad. Something in the engine? Injector pump?
For it to start back up, I've got to hold the lever for a hydraulic function and hold the pedal down. It will then blow a lot of black smoke and then be fine. Sometimes the engine will die when retracting the boom, tilting the forks, or even just turning the wheels.
Im assuming in the case you cable controls ? 2 sticks ? It starts like that because you are providing a path for hydraulic bypass and the pump is not loading up. If it was a stuck function via one of the cables/valve body wich does happen on the old cable actuated valve bodies. Cables get old and sticky, valves get gummed up and worn out but im still leaning towards pump. If a function causes the load up its usually isolated to one or two functions plus that function continues to creep in the direction of the jamb up either pushing or pulling. You would see say the boom go up or forks tilt when cranking unit over because that function would still be receiving flow. Put a gauge on the pump. It takes 5 minutes and will tell you right then and there with out doubt.
Hi there, Came across this thread and found it helpful. I have 2004 Terex telehander th644. Will only start if I hold down joystick and now it's starting to stall more and more underload. Also boom is starting to creep out like it never did before. Hydraulic pump?
This is exactly what mine is doing when starting back up after it stalls. Mine is a 2013 skytrak 8042. Machine initially wants to stall again initially, but will operate and drive as long as you are raising or lowering the boom at the same time. The first indication of this problem we had was the machine wanting to stall when tilting the forks unless we were using the throttle as you use that function. Now this. I feel this is something with the pump or something related to the hydraulic system. However, I’ve had a mechanic look at it that sent a Cummins technician out who said I need to bring it to them for a new engine. This doesn’t seem correct to me that it would run better under a load if it were the engine. Any advice or where to start to diagnose this? Cummins wanted me to haul the machine to them for an engine they quoted me $34,000 for
Hey Buddy did you solve your issue ? I got 2015 skytrak 10054 with same issue