Belarus 250AS hydrulic pump problem

[cowrider]

Purchased this 250AS several years back. When I got it the hydraulics were not working and they had a 12v hydraulic setup on the fender for the 3pt. I bought a new hydraulic pump and found lines at a salvage yard and got the hydraulics back as they should be. 3pt worked but I didn't have a use for the remotes. Well no I need the remotes and they don't work. Installed a gauge and I only have up to 1000psi. I checked the bypass and it was ok, even swapped out with another I have but no change. Adjusting the control valve pressure screw had no effect. Purchased a new pump again and finally installed that. When replacing the pump, the manual stated to remove the drive assembly. You don't need to do that, you can replace the pump by just removing the 4 bolts holding it in. Ether way, make sure you engage the pump drive first or you may loose the 4 balls that are in the coupling. If it is engaged they are locked in. the pump just slides out. If you remove the drive assembly it is a good time to check the bearings. I had one that the bearings went out in, not pretty. Anyway, the new pump restored the pressure. Needed to reduce the pressure with the adjustment screw. I went a tore down the first pump to see why it failed. At first it was looking ok. First spacer came out ok and the seal looked ok. Gears are fine. Got the second spacer out and the seal was mashed. Looking in the body of the pump, one side is machined and the other rough. You can put the spacer in ether way but the seal needs to go in toward the finished side. This had been toward the rough side so it had been assembled wrong when made. Will rebuild the pump with new seals and put it on the shelf if I need another but will mark it in case the seal wasn't the problem. But what can go wrong with these pumps?

Hopes this helps.

 

[danofarming]

Usefull information, not many Belarus in my part of TN. Most have been used up.

 

[Steve@Advance]

Typical problem with that type pump is too much end clearance.

They come factory shimmed, not sure what the clearance should be, but not much. Sometimes people will take one apart and replace the thin shim with a home made gasket, which gives it too much clearance, or the gasket blows out.

If the end cap and the body end surfaces are good, and there was not excess clearance, it will still work.

I suspect you have an internal leak in the plumbing or a failed relief valve, stuck plunger, broken spring...

 

[rlp in Co.]

The clearances on hydraulic pumps are very close. Usually the bushings wear and the gears rub the housing. Looks like in your picture that the housing is worn.