Case CX240

Hello folks,

This is an ongoing problem that has evolved so I am still needing some help. My CX240 has no active or stored diagnostic codes, machine ck screens show good in the factory case tech manual. The engine will bog down at exactly 50% on the status screen and 3700psi which also is exactly half the rated boosted hydraulic pressure of both P1 andP2 pumps, and die if pushed further. This is NOT a fuel issue. This happens with any hydraulic function on the machine, even tracking. Installed a fuel pressure gauge after secondary filter and fuel supply to injector pump is 13-14psi when engine stalls. It’s as if the ecm is derating the power to 50%, but no codes are present, not even the 25 or so codes available for the VP44 injector pump. Is there a sensor or controller for the fueling that could be bad that is not throwing a code? Since the engine will die at 3700psi I don’t believe it is hydraulic stall. In the past when I checked P1 and P2 pressures the engine would load but not stall at the spec 5400psi. Local dealer is useless and are parts changers only, with no diagnostic abilities whatsoever. And thoughts would be greatly appreciated.

Anyone, please?

Serial number?

DAC241541

Have you checked the inline fuel filter? Some of the water separators had a screen up in the head that clogs as well. I've seen fuel may flow fine in an unloaded state but die when the engine is loaded down. There could be some rust partially blocking the screen or inline.

Both fuel filters have been changed. Full fuel flow from tank. Again, the mechanical fuel pressure gauge installed shows in spec fuel supply pressure of 13psi to INLET of VP44 injection pump all the way to engine stall. This is a derating by ecm or something only allowing 50% fueling as shown on engine output screen on display.

Shimmy1 said:

Serial number?

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DAC241541

Maybe this will help?
https://www.bluechipdiesel.com/troubleshooting-1

Non of those symptoms apply. Engine runs perfectly, starts perfectly, recovers instantly when you let up before stall, with no smoke. Revs from idle to 2100rpm without hesitation. Which is why I believe this is a sensor or load sensing issue with ecm.

gggraham said:

Maybe this will help?
https://www.bluechipdiesel.com/troubleshooting-1

Click to expand...

But thanks for your input.

I asked for you to give it because guys like alrman are going to ask for it. Does the engine smoke as you hold it down close to stall? Can we assume this is a full mechanical engine? Have you checked boost pressure?

The only reason someone should be asking for my machines serial number is if they have access to advanced database for machine specific specs. That’s why I gave it. The engine does not smoke before stall or after it recovers when I let off it before it stalls. The engine is a 5.9 Cummins with the VP44 electronic injection pump but it has mechanical injectors. I do not see a boost pressure sensor anywhere in the turbo up pipe so not sure if it is set up to monitor boost pressure. Turbo spins freely. What is strange compared to anything normal with those cummins engines is the engine response is instant from idle to governed speed, and it recovers instantly with very little to no smoke as normal if you release a hydraulic control before stall. Again, it’s as if the ECM is derating power output to only and exactly 50% as shown on the diagnostic screen just before stall at 3700 psi, also half of the spec max hydraulic pressure.

Engine ecms and that vp44 are troublesome to say the least but usually you'll have ample codes. Roughly how high are the hours? Can you describe symptoms differently. Ex. If your watching rpm on the display track on flat ground how much does the rpm drop? And if you walk slower can you keep rpms up? Can you notice the stock in speed change as pressure builds or does rpms drop to fast?

rmllarue91 said:

Engine ecms and that vp44 are troublesome to say the least but usually you'll have ample codes. Roughly how high are the hours? Can you describe symptoms differently. Ex. If your watching rpm on the display track on flat ground how much does the rpm drop? And if you walk slower can you keep rpms up? Can you notice the stock in speed change as pressure builds or does rpms drop to fast?

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Great questions. Machine only has 7600hrs. Engine runs perfectly, other than the reduced power issue and when you load to stall you can watch the rpm’s fall to stall. All hydraulic functions have the same affect, you can feather any control including tracking until engine stall. Regardless of whether the engine is idling or full throttle, when you hit 3700 psi on either pump (P1 or P2), and the power display approaches 50%, if you don’t let up engine will stall quickly. But if you let off in time before stall, it recovers instantly with almost no detectable smoke.

Does anyone know if there is a hydraulic pressure sensor that sends a signal to the ecm to ramp up power as the pressure increases?

#28 may be your problem. Sorry no spec on it. Only thing I have on it is for the B series but basically it did similar with the straight CX Series. I believe it does reference the LX series which is the CX series. The LX2 is the CX B Series. Link Belt manual. Hope this helps.

Doesn't sound like an engine problem to me. It sounds like the pumps are not destroking and the combination of flow and pressure is what is stopping the engine. I am not familiar with your particular machine but have some experience on Link Belts in the past. Do you know if the pump is a Kawasaki or a Uchida? Those were both negative flow control pumps back in the day. They used pressure compensation to provide a sort of load sensing ability. There was a solenoid on the pump that controlled the high end of the output by regulating a pressure control valve.

gggraham said:

#28 may be your problem. Sorry no spec on it. Only thing I have on it is for the B series but basically it did similar with the straight CX Series. I believe it does reference the LX series which is the CX series. The LX2 is the CX B Series. Link Belt manual. Hope this helps.

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28 and 29 are upper travel and pilot sensors. It was showing a code for one of those but I replaced both of them and the code cleared. Still same problem. Thanks for your response though.

John C. said:

Doesn't sound like an engine problem to me. It sounds like the pumps are not destroking and the combination of flow and pressure is what is stopping the engine. I am not familiar with your particular machine but have some experience on Link Belts in the past. Do you know if the pump is a Kawasaki or a Uchida? Those were both negative flow control pumps back in the day. They used pressure compensation to provide a sort of load sensing ability. There was a solenoid on the pump that controlled the high end of the output by regulating a pressure control valve.

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The Linkbelt LX240 is the identical machine. Sumitomo made both, and yes they are twin Kawasaki pumps. Would not destroking still kill the engine at 3700psi when the relief valve specs for both pumps are 5400psi at boosted pressure, 4700psi standard?

De-stroking the pumps means they put out less flow as the pressure increases. I'm going to guess that your pumps put out about 40 gallons a minute per each and around 2,000 PSI. Figure 80 gallons a minute then and we can ballpark the horsepower needed. It's about 1 horsepower per gallon a minute at 1,000 PSI. 80 gallons a minute then at 2,000 PSI would be about 160 horsepower. I'm sure your engine has that much power but let's kick that up to 3,000 PSI. Now you are having to produce 240 horses from the engine. You probably still have enough. Get up to 4,000 PSI and now that little fuel saving engine is going to just stop turning when the pumps want 320 horsepower. Go to 5,000 PSI and your engine has no way of producing 400 horsepower. So the designers figured to compromise and turn the output of the pumps back as that pressure climbs by de-stroking the pumps. Instead of 80 gallons a minute they might drop back to 40 gallons a minute and now you are back at 160 horses. The machine functions slow down some and you just learn to work with it.

You could try operating a function that only uses one pump like the bucket function or just one track at a time and see if it kill the motor.