Hi everyone, new to this forum, having a problem I cant figure out. I have a 2001 CAT 302.5, 3000 hrs, worked good in the fall, this spring i fired it up and no hydraulics at all. Fluid is good, filters are good, hydraulic disconnect solenoid is engaging, I pulled it off to confirm the action, check all electrical to make sure. It doesn't seem to be a electrical issue. I pulled the pump off to check the coupling to the flywheel, everything looks good. That`s where I`m at now. Any help would be appreciated. Also if anyone has a CAT 302.5 4az1-UP shop manual available, that would be helpful. Thanks, Mike.
Have you seen any evidence of........... ?????????
Hi Vetech63, nope, no evidence of any critters inside the machine. I’ve had that before on vehicles though.
Do you have an electrical schematic.? Shout out if one would be helpful. Be on the lookout for Cat publication RENR2840. I can't see anything immediately available on online selling platforms. This outfit sells genuine Cat ones - https://www.servicemanualpro.com/?page=Products&searchbox=4AZ
Hi Nige, I have a electrical schematic for my machine, it was very helpful in diagnosing the electrical side of it. I found it online. And Thank you for the heads up on the Manual info!
Try checking main pressure at the pump, to make sure your pump is spinning. I have seen the plastic flywheel to hydraulic pump gear be striped out.
Hi Muddog, thanks for the reply. I pulled the pump off to check the nylon gear, and it is all intact still, confirming that the pump is actually spinning. I’m thinking now that it has something to do with the pilot hydraulic system. I also have a heavy duty mechanic friend that is doing some research on the system to see if he can figure something out.
Does he have a document explaining how the system works.? If not, would he like one.?
Hi Nige, thanks, that would be great if you had something. He was asking about the hydraulic schematic for that machine. The pump doesn’t seem to have a pilot line to engage it, it only has three large ports, two main high-pressure pump ports, and one port for the pilot pump. I’m also going to send the pump to a local hydraulic shop to have it checked out while it’s off the machine. My heavy duty mechanic friend said that maybe the pump is not engaging ? Mike.
That's do-able. Check your PMs.
Good deal, let us know what yall find
Hi muddog, I have the pump off the machine, I have checked the gear and it is in good shape, confirming that the pump is spinning, I’m currently sending the pump to a hydraulic shop to have them check it out before I put it back on the machine. I also have an HD mechanic friend that is researching the system to see if he can figure out why I have no hydraulics. Thanks Nige, for the hydraulic schematic.
I would try to verify that you have power to and coming out of your arm bar switch ( the lever to your left while in the cab). When you actuate the lever. Double check fuses. I would have left the pump installed and just put a pressure gauge. That would let you know if the pump was putting out. Still let us know, I'm very curious about what it is Thanks
I'm sure you checked it but it's worth checking... the bolt that keeps the pump gear on the shaft...check it for tightness. If it was a little loose. Possibly spinning on pump shaft #5 in the pic.
Hi muddog, I’ve gone through all the electrical and everything is working as it should in the machine relating to the arm bar switch, I’ve confirmed the action at the hydraulic disconnect solenoid, i’ve also checked the pump shaft, everything is good in that respect.
Well that's good!....I hope it's something simple...let us know
I Finally got back to work on the 302.5 and figured it out. The spool valve behind the hydraulic lock out solenoid was stuck in its bore, took a bit of work to get it out and cleaned up, but its back in action! Big thanks to Nige for the hydraulic schematics! Thanks again for all the help! Mike.