Weaker/Slower Hydraulics after warmed up - Kobelco 35sr-3

[Newfiestang50]

Hello Forum,

I have a 2006 Kobelco 35sr-3 with 1440 hrs on it. As the title states when i am working the machine several hours the hydraulics seem to get slower and weaker. Its not to the point were I cant continue but its definitely noticeable. I only have the machine a year and probably put about 100 hours on it, cant say for sure if it was like it all along or not since I've only done a few jobs that require me to be working the machine in excess of 3 or 4 hours without stopping. Most of my jobs are either shorter or require periodic stops. I think the issue is related to heat but I dont see a temp gauge on the hydraulics, the engine temp remains normal according to the gauge on it. Also, all functions seem to slow or weaken once this happens. Could this be a deteriorated fluid problem of some sort, dont really know when it was changed last. Any help would be appreciated.

 

[Newfiestang50]

38 views not one response.....nobody....???

 

[lantraxco]

Not much to go on here... One thing you can check easily, though I recommend draining the hydraulic tank to do it, is the suction strainer in the tank. It's on the end of a rod directly below the breather you just wiggle it loose off the suction pipe and pull it out. Check the strainer is choked with gunk.
Check the color and smell of the hydraulic oil, if it's dark and smells burnt it's definitely a heat issue.

The oil cooler is tucked in behind the radiator it looks like, it may be partially plugged with debris. Maybe have somebody shine an LED flashlight from behind to see if you can see through the radiator core if it's clear. A good blowing or washing wouldn't hurt, but don't pressure wash and don't do it with the engine running.

There's a bunch of variations in the parts schemes but the system typically on these little guys uses a single rotor pump with two outlets, a pilot pump on the back which also runs the blade and boom swing. Main relief valves should be in the neighborhood of 3,300 psi, the dozer and boom swing section relief 2,900.

Another issue is you may be losing pilot pressure, I don't have that setting, if you can get hold of a manual, or the specs, there's a solenoid valve manifold with the safety shutoff solenoid valve, a second solenoid valve for two speed travel maybe? and an adjustable valve for setting pilot pressure for the controls. If you can find a place to connect a gauge you can check pilot pressure cold and again when it starts to lose power.

If you can't build enough pressure to get close to the main relief pressure, there is an adjustment on the main pump, but you will need the procedure out of the manual to set it, or maybe somebody else on here will know. It's supposed to be balanced between the system pressure setting and the engine power available.

Not sure any of that will help, but maybe it's a start.