Is anyone out there knowledgeable about R-series wheel loaders?

[sturdavj]

I am looking at the hydraulic schematics for the R420/520, specifically the cooling circuit, there is shown a thermo switch (on; 110c). Does this switch open and dump to outside the system when oil temp rises above 110c? It appears this is an open line…

This equipment sees “a lot” use loading semi trucks, majority of the movement is back and forth. As time goes on it begins to leak oil, it appears to be coming from a vented outlet, which I am thinking might be this switch?

Not sure why this 420 is leaking and the other two wheel loaders, seeing the same service, are not?

I am still searching for a Kubota FSM for this equipment

 

[sturdavj]

Thanks Vic, hope you'r still hooked up

In the drawing you have provided, it appears to be the component that fitting #160 is screwing into. ?

I had another look at it last night, I now believe it is not on cooling circuit. I have only have the owner’s manual schematic to trace out the system…. Nightmare

What is happening is after it heats up, the fluid starts flowing out of what looks like a vent. It is upright and has a canister over a screened filter. Similar to the one in your posting, can't rellay tell . Last week I removed both the can and filter, cleaned re-installed them, as well as the cartriage filter and the HP filter. The leak has slowed down, but not stopped.

Last night I drained the reservoir tank (oil was very dark, quite a bit of water at first) I don’t know the last time tank was drained, but I understand it has been longer than 4 yr’s. I pulled the suction filter it was dark, but not what I would consider extreme. The plan is to refill tank with Chevron RPM dello 15-40WT (same-same). OM says to do this every two years, what ya' think ?

These units are used daily as forklifts loading semi’s for a large Nursery operation so they a lot of service.

 

[sturdavj]

I changed out the 11.5 gallons of hydraulic fluid / suction filter. Pressure washed the radiator cooling fins, full of dust. (Other 2 filters were changed at the beginning of this process.)

Loader ran cooler, however when the temp gauge climbed above 2/3 rd’s the over thermo switch opens and dumps oil, when it cools back down to ½ way, switch closes & oil stops.

Talked with our local Kubota dealer (never a pleasant experience, the Gresham OR. dealer is known for leaving the serve out of service, providing just the ICE. Hope your dealer experiences are more positive). They are pretty confident it is the thermo switch; we’ll be changing that out next, for $300.00

I am not sure of the normal operating temp, the switch is operating however it may be opening & dumping oil before it reaches maximum threshold. I guess we will know when the switch gets here in 3-4 days…

 

[sturdavj]

Replaced thermo switch, still leaking HYD fluid out of axle vent

 

[KubotaTech]

I've seen and heard of these units pushing hyd oil out of the rear axle vent because the park brake seal overheated and burned up causing the hydraulic oil to be pumped into the rear axle. The rear axle uses gear oil so if you are getting hyd oil coming out, something is definitely wrong.

 

[sturdavj]

Yes you’re correct. Thanks for your help

Through the process of elimination and having found a Kubota dealer on the other side of town (~50mi away) with a helpful service department. I have determined it as you have said, the seals in the brake unit have cooked out, allowing hydraulic (motor oil) to overfill the differential.

I have ordered the repair parts from Pacific Tractor & Implement, in Hillsboro, OR.
They'er on backorder, I will be changing out the parts first of next week