Mf 6490 hydraulic pump failure

[dee]

You have a load sensing problem then.
It's either gonna be one of the slices or the orbital.
Try getting an inner slice to try as this also controls the 17 bar circuit and might explain the low pressure on that circuit

 

[Masseytinker]

Eventually getting back to look at this tractor again, have managed to get the right couplers for the original test points.
The Steering is still locked up- when I hold a small force on the wheel to turn it, eventually (7-8 secs) the steering will begin to turn around easily.
The low pressure circuit is fine at 17 bar.
The low pressure pump supply it ok at 5 bar.
With the guage on the XLS pump controller, I'm getting only 1-2 bar at idle (think this is ok?)
When I pull the spool lever the XLS pressure immediately rises to 190 bar.
When I turn the steering either direction, the pressure takes a while to begin to build, eventually when it gets up over around 30 or 40 bar the steering starts to turn.

 

[lexion780tt]

Sounds like the priority valve is stuck or stuck ls line dose the steering work if you hold a spool in?

Take the priority valve spool out if it still dosnt work change the orbital

 

[Masseytinker]

Is the priority valve spool on the top of the outer slice? (Trailer brake slice)

 

[Masseytinker]

Sounds like the priority valve is stuck or stuck ls line dose the steering work if you hold a spool in?

Take the priority valve spool out if it still dosnt work change the orbital

Took the priority valve spool out, pressure at pump controller stays at around 185bar, steering works.

No sign of the priority valve spool sticking, but there is a strong vacuum when taking it out with magnet. Not sure if that is normal or not, the other spools come out easier.
thinking I need to take the 2 slices off again and give the spools a closer look

 

[lexion780tt]

Just chech there is pressure at the ls line when trying steering

Normally if ls isn't working Pulling a spool will make steering work but by the sounds of it priority valve is sticking or has internal leak

 

[Masseytinker]

Just chech there is pressure at the ls line when trying steering

Normally if ls isn't working Pulling a spool will make steering work but by the sounds of it priority valve is sticking or has internal leak

The pressure is just very slow to build in the LS line when trying steering. Hence the delay in getting flow to orbitrol, before steering eventually works.
When a spool lever is pulled the LS pressure does rise quicker and the steering works.
I've taken off the LS line from Orbitrol back to the distribution slices on the RH cover and blown in out- no obstruction in the line.

 

[lexion780tt]

Sounds like you need a new orbital unless one of the chech valves is stuck

I seem to remember there is a orifice in the union ontop the prioritie valve the steering ls line goes through I might be miss remembering but worth a go

 

[Masseytinker]

Sounds like you need a new orbital unless one of the chech valves is stuck

I seem to remember there is a orifice in the union ontop the prioritie valve the steering ls line goes through I might be miss remembering but worth a go

Think it has to be an issue with the Orbital.

Having trouble finding one- its a Danfoss OSPC 125 LS.
Only 1 I can find online is an OSPC 200 LS listed for the Massey 8100 series on John Conaty Website at around £500. I think this would work, just higher capacity/flow.
Any suggestions for who might sell these? Local Massey dealer looking for over £1200 + VAT.

 

[lexion780tt]

If you get the part no off it hydraulic place should be able to sort it.

Probably be a danfoss one

 

[Masseytinker]

Fitted a new Orbitrol to this and it has made a good improvement in the steering, however it is still sticky and can lock up for a second or 2 before turning. (Nowhere near as bad as it was before).

Haven’t had a chance to properly bleed the brake and trailer brake system.
Hoping that some air in the system could be affecting everything?

 

[Masseytinker]

If you get the part no off it hydraulic place should be able to sort it.

Probably be a danfoss one

The XLS load sensing test point is measuring no standby pressure.
The main high pressure test point is showing 20bar pump standby pressure (should be 25).
Don’t know why she is not holding any LS standby pressure, it will build up if I turn steering or pull spool lever, but drops off to 0 when idling and no functions activated.

Thought maybe she was losing oil via the load sensing pipe to spool valves, blanked that pipe off and no change. Same thing with other load sensing pipe to Orbitrol.