As my title states, 2008 CAT 930G, Stalls when dumping bucket, and think a Ride Control issue may be related, but wouldn't surprise me if it coincidental either. Had Ride controller Accumulater Recharged, new valve and solenoid on Ride Control Valvebody, Seems to work intermittently, then quits altogether. The Relay behind the entry switch loses constant power as soon as joystick is moved to dump position. It is the constant power, not the switched power to turn ride control on and off operated on the dash, 100% sure of this. This Loader has been nothing but trouble since day 1, in the last 8 months alone my employer has spent over 20 grand in parts on this machine, countless hours of down time, and we can't get an 8 hour shift out of this thing, has 5500hrs!. It's very frustrating trying to keep this thing at work. Everyday is a new troubleshooting adventure!
By stalling out I mean the Engine quits, like pressure overloaded on the pump enough to stall out the engine
Buy a Volvo...If you think the ride control is part of the problem, what happens when you shut it off. We had a JD loader do that, but it was idling to slow.
Yea...buy a Volvo...LMAO! The Ride control doesn't work when turned off either haha, reacts the same when turned on for the most part....Adjusted bypass valve and I now have ride control, and stalling has stopped, but it isn't in the position it's supposed to be in, seems I have a blockage/collapsed line or valve not opening when it should.
Should be clearer on that, bypass valve has a square bolt head in it with markings to match up to a specific place. Where it's lined up to now is about halfway between the 2 sets of marks. Almost to the point of the boom drifting down on it's own without anybody on the controls. It's the valve for lowering the boom if engine quits and there's no pressure to the pilot valves on the joystick.
Hi I have the exact same problem with a 08 930G 5500hrs. Stalls at idle when dumping. Have tested all relief valve pressures and they are correct as per the Manual. Swapped over the check valve with the lift circuit...no difference. Checked the resolver valve.. fine. Getting desperate even changed over pilot oil lines. No difference. I do notice that when releasing the dump back to HOLD full 3750psi pressure remains in the head and rod end of the cylinder until placed in the CROWD BACK position when the pressure is released. Might have to look at the ride control circuit. Did you have any luck m.j.glover or has anyone solved this problem. Thanks Robert
My memory is challenged about this but recall a wheel loader locking up the bucket dump and lower circuits if the controls were engaged fast, slow modulation was fine. The problem was pilot pressure was too high. Slight movement didn't let full pressure in to move the spools, this pressure also unlocks the drift reduction valves to allow the two functions. The section of control valve body with the pressure reduction valve in it was cross drilled in the wrong place and damaged the taper that compressed the seal on the pressure reducing valve and damaged it, allowing it to blow out. This allowed system pressure into the pilot circuit and could lock the drift reduction valves. Resealing didn't last, needed a new valve section. Later Bob
Have checked the pilot pressure and reads correct. The strange part with mine is it is only the dump circuit. Lift up/down is fine and crowd back is fine. Just dump loads it up and stalls the engine at idle.
OK, sorry for the lack of response, been so busy at work and getting nothing done.....just how it is at the moment. The Loader hasn't changed in it's actions, but I did notice that in the full dump position on joystick everything is fine and fast, partial movement in joystick to dump bucket slowly ALWAYS results in an engine stall if held for slow dumping. No fix yet.:Banghead The loader has about 5500 HRS, same as yours SWRiverstone. I wonder if this is a problem CAT knows about, but just won't let anybody in on some info to fix? Think the powers that be are going to call in the big guns (CAT Technicians). I'm at a loss, and have limited test equipment. (as in Phillips screwdriver, BIG hammer and Utility knife with broken blade. haha) But from the information you've given me and my own intuition, seems that it's either in the Hydraulic Manifold, or the Back Pressure Valve. But again it's only a guess :beatsme. Kinda like chasing a rabbit through the woods and hoping to catch it!
Hi I am trying to fix a 930G with this exact same problem. Are there any updates here
Call cat tech line 303 739 3140 they are very very helpful
Hi, I also have a 930G that does the same thing. Stalls out, especially on idle, if the bucket is dumped, run over relief and boom up, or curl bucket & boom up. If it's done at idle, you'll lose throttle control, what I mean is, it'll start to bog down, then if you step on the accelerator pedal, it won't rev up at all. Has anyone came up with a confirmed fix for this? this machine has 8K hrs on it and has had one problem after another as long as I've been here, mostly leaks, but also several other major repairs. Some reply's would be great!
hi hdmech. Does yours stall on just the dump function or all functions. If it stalls on all functions I would think its a load sense issue with the pump. I'm not sure if these pumps are negative sensing or horsepower controlled without a schematic but the one I'm trying to fix just stalls on the dump function like the others two blokes said, which makes me think it's a local problem with the valve or a dump valve I havnt found. I was hoping for an easy solution as I don't have access to a workshop manual to be able to read a schematic and the owner of the machine is too tight to buy one which makes it hard
Hi Chris, Just seems to be the bucket circuit on this one. If I run the bucket circuit over relief, it will stall, just does it faster if I run boom up at the same time. I was hoping for something easy too, but doesn't look like it on this one. I'll study my manual a bit and see what I can find, I'm not familiar with this system, would it have a different load sense circuit for different functions? that seems complicated...
Set the cut off on the compensator lower that the port relief
Not sure what you mean Mikebramel? I'm reading about the "combination" valve in the bucket circuit on this machine, it's a diverter and relief valve in the tilt/dump circuit, looks like this may cause issues if it's stuck, has a broken spring ect. maybe? it seems like the pump isn't getting a signal to destroke when the tilt function is stalled/ran over relief and builds too much pressure, stalling the engine
Hydraulic power is flow x pressure. If you have the cylinder at the end of stroke, the pressure alone will not overcome the engine. There needs to be flow at high pressure. The flow would be coming from leakage. Which I think would be a problem inside of the control valve. I would adjust the port relief
What is the dead head pressure for the bucket compared to the boom?
The loader I'm working on does this through out the whole stroke of the cylinder. You might be onto something with the pump compensator. I will have a look at that.
Before jumping in adjusting things - do you want the hydraulic schematic and the System Operation document..? Drop me a PM with your email address and your machine Serial number if you do. The poster from Canada (see post #12 on Page 1) has found that when he did the first test of engine stall speed the engine was 200RPM below the minimum specified. It would seem as though he has an engine problem that needs rectifying before even thinking of digging into the hydraulics. The specification is 2290 +/-50 RPM with all machine systems at normal operating temperature and the transmission in 4th speed with the converter stalled. Chris, maybe it's worth trying that as a first step...? Mike, the implement pump on these loaders is a load compensating system. When the pressure in the system increases the pump should de-stroke. This would also be true if a cylinder got to the end of its stroke. It appears as though this isn't the case with these problem machines, although I will caveat that by saying "get the engine right first" ........
I agree, a fuel problem will cause similar symptoms, trying to get someone with a laptop to check the fuel system since I don't have ET. With a load sense hydrualic system, the pump should destroke when high pressure is sensed. The pressure relief is working because functions can be run over relief and the engine won't stall, if the oil was dead headed, like the relief was set too high/not opening something would break. In any case I would be looking to a system relief valve, not the circuit relief valve on the port. In this case the compensator should destroke the pump via the load sense system to relieve pressure.
You don't need a laptop to check the engine stall RPM surely..? You'll read that straight off the revcounter on the dashboard. At least it will give you an idea if engine power is there or thereabouts or if you need to dig deeper on the engine side before moving to the hydraulics.
That's what I did to find out it's running 200RPM lower than spec. Now I need a laptop to go further. Maybe the old VP44 is getting weak, or injectors?
Ooooops, sorry. Getting confused with 2 posters. How many hours on the machine..? Original injectors..? Maybe it's the time to treat it to a set of new or recon squirters and depending on how they go maybe a turbo as well..?
No worries Nige, 8k hrs on this unit, I agree, might just put a set of reman injectors in for PM and see. No black, white or blue smoke though, which is a bit strange if the injectors are going. Hoping to get a field tech with a laptop to drop by and just check it out
Agreed. Doing a bit more diagnostics might be a better option rather than just blndly throwing money at it whether it needs it or not.
With this many hours, it's probably a safe bet the injectors are ready to be replaced as regular PM maintenance anyway so it's not a big loss if that doesn't correct the problem
Here's an update. I had to break down and get the local dealership resident mechanic to check it out since I don't have the cat ET program on a laptop and this thing has an electronic pump. Manual says check torque stall, if that's low, deal with the fuel problem first, then test the hydraulic system. He decided to ignore that process and jump right into the hydraulic system. He claims to have taken 2 valves out of the control valve bank that were in pieces, I didn't see the supposed broken parts, he ordered & installed new valves when I was away on holidays, the problem still happened, in fact it was worse. Just dumping the bucket would stall the engine. I phoned and told him about it. A week later he calls me back and says he found some info, a TSB or something about this series of 930 having injector problems and the serial number of this one was in the range that was affected, thanks sherlock! I ordered a set of reman injectors, installed, set the valves and repaired a coolant leak (unrelated) and it's not stalling anymore, go figure, hopefully this cursed machine makes it through the winter so it can be traded off next year!
If that'd been me that would be the point at which I would have pointed out that I was the one paying him and either he'd follow the procedure recommended by the manual or don't let the door hit him on the ass on the way out.........or if his way didn't fix the problem all his time & parts would be at no cost to me.
I agree, this guys supposed to be retiring at the end of the year, but I think he already did. There's no accountability here, the boss just pays the bill, they should fight this one, it's not the first time this guys done this and I've had to fix the problem