255 power steering pump third failure

[LenR]

I've got something causing power steering pumps to fail in less than 100 hours. They start leaking out the front seal into the engine oil. This is the pump with an internal reservoir that is plugged with an O-Ring plug.

I think it's building pressure inside the pump forcing the oil out. I don't see any design to relieve any pressure from heat, just the air space in the upper half of the reservoir.

I discussed this with my local MF dealer service, they seemed less than anxious to work on it. They suggested plumbing in an overflow tank or remote reservoir by converting the plug to ORB fitting.

Any thoughts? It's too good of a tractor to give up on a fix

Thanks

 

[Dieseltech]

That pump needs an air space above the oil level, and if the can is installed wrong it may just be too full of oil. Can only needs to be just over half full for the system to work. They were never vented, and never gave any trouble. I did have a pump burn up on a 175 years ago, but it was caused by the pressure line being brazed on. Line was nearly brazed shut, and pump was blowing the relief valve constantly which over heated the pump..

 

[LenR]

Yea, the first replacement pump had the filler at 1-2 oclock, so it didn't have the designed air space, the 2nd one was at 3:00 like it should be.

Not sure where else to look. I had a bushing go out of the steering arm about 2 years ago, I replaced the lines from the steering motor to the cylinder then.

I just noticed on the parts list, there are steering motors "with relief valve" and "without". I don't know which I have, this is the later model diesel (AD236). I wonder what that relief valve controls? I think if my problem is pressure, it would be on the return/resorvoir side. Maybe I have a bad relief valve causing heat? The return circuit runs thru the bottom of the radiator for cooling and I've replace the radiator in the last 1000 hours and changed the coolant every few years.

Thanks