Hi, I'm back again with another question from a Novice Cat Owner. My machine is back up and running and so we are now focusing on the next issue. Which I believe to be an overheating issue of the hydraulic system. My D4 works very strong for the first few hours then it looses strength and I have to park it for a few hours before it regains strength. What should I check for? I recently had both the radiator and oil cooler cleaned-- but they are old and in bad shape. Could this be where the issue is coming from or is it more of a Hydraulic issue. I've been told there is a specialist who can come and check the pressure of the hydraulic system-- is he the one I need to call to address this issue or is it from somewhere else. Thanks Guys
Update: So I had the specialist come out and check the pressure. We are at 210psi when the machine first starts in the morning-- however after working a few hours it heats up and the pressure dropped to 80 psi. He told me this is an indication of worn out Hydraulic Pumps and that I need to do a full overall of both pumps. And so the journey continues...
I believe this is the part in question:
I don't know where your expert is getting the pressures from but those specs are nowhere near what the operating pressure should be. Maybe someone will come along that can steer you right. My guess is that those pressure are charge pressure to the pumps.
Post your Serial Number again. I'll look up the correct testing procedure and also post the specs.
Thank you for sharing this insight-- to be honest I am questioning them a lot and that's why I am bringing the information here.
Thank you so much
See attached. The real pressure testing starts on about Page 6-7/ Main relief valve pressure specification is 2500psi.
This is very helpful thank you very much.
It would be interesting to test the main relief pressure when the machine is cold (yes I know the test procedures say to get the oil warm first but bear with me) then test it again when the machine gets hot and loses power in the blade hydraulics, then compare the difference.
I asked for a bit more clarity on what they tested the first time and this is what they shared with me.
Looses strength? Such as low power? No push? Or, is it weak hydraulics? I’m not tracking, much like your yellow tractor.
No Push would best describe it.
Thanks for the clarification. Let’s check some easy things first. That generation of corporate fuel cap is known to have issues. Make sure the fuel cap is breathing like it should. When was the last time the fuel filters were serviced?
Ok-- I will check it tomorrow. Could I operate it without the cap to see if there is any difference? It's a brand new fuel filter. I actually just rebuilt the motor with new pistons, rings and bearings. Before the rebuilt it could work all day without this happening. *Note the engine does not change sounds when this happens if that's a tell. Now when this happens we park it for an hour and when it coils down some of the strength returns.
I see. You can leave the cap loose. Or, just try opening it and see if a vacuum exists in the tank.
Ok I will try this.
Did you see this? Do you know what this means?
Ah, so you are talking about a loss of power in the hydrostatic drive system, not the implement hydraulic system. Your OP wasn't clear on that. Attached is the testing procedure for the hydrostatic system. Please note that for a few tests and adjustments there are different specifications/procedures depending on the machine Serial Number. Your machine with S/N 6BS00315 falls into the "6BS1-635" group. I'm still not sure exactly what system pressure they were testing with the 35 bar (+/- 510psi) specification above. EDITA: I'm not sure what they were testing with the 210 bar (3050 psi) circuit either, because the high pressure specification is either 430 bar (6240 psi), 440 bar (6382 psi), or 475 bar (6890 psi) depending on the test that is being conducted.............
Looks like you have pump problems.
It’s not uncommon for this stuff to happen after an invasive repair. Contamination control is so important with a hydrostatic system. Some innocent dirt into a open hose or hydraulic cooler and bamn! Or, a shop rag left behind. I hope that’s not the case.
No Vacuum.
My apologies I'm truly a Novice and because I'm located in the Rural Countryside of Ghana most the mechanics I am dealing with are "shade tree" mechanics. You guys have been truly helpful with connecting the dots.
I'm pretty sure it was caused by this-- because the machine was very exposed during the processes. I could easily imagine some dirt getting in one of the hose ends. One thing I will say is before this the hydraulics used to get very very hot-- like uncomfortable to site on the machine hot. In trouble shooting it I had both the radiator (inside and out) and oil cooler (outside) cleaned. While it is a little frustrating I understand this is just what comes with old machines and learning something new. One day I will have a new machine.
The Hydrostatic Pump (Piston Pump)?
Again I want to thank you all for taking the time to contribute to my post. I truly love being a new CAT Owner and while my first machine is small and old I know it will lead me to having a bigger and better one in the future. Here is a picture of what I'm working on now.
Keep us updated on your progress. Looks like an interesting project. Is that a new mining claim?
Hi Nige, Is there a repair/rebuild kit for the pump I need to service?
I am working on a Community Development Project.
Have you done the tests that were listed in the attachment I posted earlier.? If so what were the results.? The 169-0562 pump you listed earlier is made up of three separate pumps. There is no repair kit for any of the three. Also, and I would hazard a guess here, it's going to require plenty of out-of-the-ordinary tooling and maybe a test stand to rebuild those pumps and to test/adjust them to specification after the rebuild.
Hey Guys-- I'm still at it... Trying to solve a hydraulic hose problem. I had a bunch of hose replaced and some how the positions were not labeled well. I have this diagram but am wondering if anyone else has any better diagrams that will show me where every hydraulic hose goes to. Much Thanks!
Did you end up putting a pump on this machine?
I have a friend who has a 320DL and had the symptoms you describe. After a new hours the machine would lose power and quit. He thought it was dirty fuel, but when I inspected it you couldn’t get the fuel cap off. Fuel tanks need to be vented so a new cap fixed his problems. Not saying this is your problem but like the others describe you might start there.
This thread is a couple years old, Dec 7,2022 was the last time the OP responded.