I've got an older TJ450A line skidder (1986) with a charge pump pressure issue (Clark Trans HR328-4). A couple of mornings cold start ATF was leaking out of the regulator stop valve. Seemed to stop leaking when the engine and trans were warm. Took it apart and inspected, put back together - and no pressure. Took the valve apart again and replaced O-ring, replaced the three O-rings between the regulator valve and housing. Gaskets are good - took the filter off and screen (will replace filter and clean screen) - so other than replacing the one last O-ring in the regulator (safety valve) - running out of ideas. Pump itself looks good - but am contemplating replacing the charge pump. It appears that the pump is unable to suck the oil out of the transmission - whether it is the pump or something else - I am not sure. Anybody have any other ideas - anything else to check before replacing the pump?? Thanks in advance - Robson -
Hi, i`m not a guru to this skidder, i am in the dumper/excavator business. Anyway, is this pump sitting on the outside so you have access to the pump ports? If so try opening the pump pressure port, that way the pump sucks oil easier. Sigurd
Hi Sigurd - the pump is on the outside, however the valve caps on the regulator cannot be easily taken off while in place as access is poor, there is a rolled steel pin holding the caps in & they are spring loaded. There is a NPT plug on the top of the regulator valve assembly - I opened that while the engine was running but no oil showed. There is also one fitting coming off the charge pump that goes to the pressure gauge. Today, I did see the gauge go briefly up to 50-100 psi, but then fell back to zero. Had the pump mostly apart today as well, and it looks OK throughout, but I am no expert either! Dave
Hello hope to help. Does your charge pump whine or make any noise, usually if you get pressure at first then it drops of its because of a restriction on suction side, plugged suction screen, collapsed hose. No pressure at all usually loose hose, cracked pipe or pump / drive problem. Let us know what you find.
Clark Charge Pump on TJ 450A skidder Got the charge pump working - a couple of suggestions in this or other forums suggested 'overfilling the transmission' - I had double checked the O-rings between the regulator and the housing - replaced them - as it appeared that there was not enough suction. With extra ATF in the transmission, the pump started to prime - and squeal a bit - but is now working! Thanks to those that had suggestions. BTW - this transmission (3HR328) does not have a screen in the sump anywhere to be found.