I have a 2020 CAT 303.5E2 CR Serial Number CAT3035ECJWY06661 that I purchased used from a CAT dealer. A while ago I thought I had an issue with the down force on my front blade but I figured as a new operator I was accidentally triggering the float mode. Yesterday I had to dig a hole to bury a horse, and it took me about two hours. By the end of that period my machine had no noticeable down pressure. Blade could not lift or stabilize the machine. However when I first started using the machine it worked great. I was thinking maybe my Hydraulic Control Pilot Valve leaks when the hydraulic oil gets hot. If I'm not using the machine for long periods, the blade will lift the front of the machine. Although I haven't tried it again since last night. I see that CAT has some parts listed under part number 438-8361 that look like they are valve service items: Seat, Plug, Ball, and Seal-O-Ring. Would it be worth a try to just get those parts and try and repair my control pilot valve? Or would it be better to just get a complete 438-8361 assembly? Could there be something else at fault with the machine that could cause this issue? A new valve is around $700 so if my issue isn't related to a leaking/faulty pilot valve I would appreciate the insight. My machine has about 1700 hrs on it and it is just a DIY machine.
I would suggest that you (and your wallet) might be better diagnosing the problem rather than firing the Parts Cannon for what may be little or no result. Do you have access to an infra-red thermometer.?
Yes, I do have one.
Could your blade cylinder be by-passing, how much pressure on the blade down function. Does that pressure change as the machine oil gets warmer. Better do some testing as Nige said before ordering parts. Simon C
Ok. So with the machine cold raise the blade up to full height and hold the control lever in the raise position. With the engine at max rpm point your temp gun at the top end of the blade cylinder where the piston will be. Check for any increase in temperature in that area versus the rest of the cylinder. If you find it that would indicate the piston seals are bypassing.
Thank you, I will try that. I used the machine again today and it did have down pressure when cold. But it sounded like something became unstuck before it had the down pressure. Is there a solenoid that puts the blade into float mode that may be sticking? I'll have to look through my hydraulic schematics.