New Holland front suspension woes

[JohnDeere8530]

I have a fairly elderly/well used T7 260, around about 2016 I think...

The front suspension has been problematic in the form of :-

It creeps down to its stops when parked up
When you start it up and it is used, all is well for a while, but then in mid use it will often collapse down again.

Had fitters out a few times and have been unsuccessful in finding the problem. When they recalibrate it, with a laptop it seems to operate normally again, but only for a short while. Then the problem come back.
The two electro-hydraulic valves that work the suspension, that are situated near the top of the suspension ram have been changed with the same parts off one of the much newer T7s lying about. This has made no difference, the problem is still there.

The fitter now thinks there are more valves, that operate the suspension are situated under the cab and is thinking of changing those over.... I am almost reluctant to try as he seems to be stabbing at parts almost blindly now.

I did think it was a leaky internal ram seal, however as there is a different displacement each side of the plunger in the ram, I thought this to be unlikely, as the suspension would only go partly down and a laptop recalibration would not have helped it.

Anything else it can be, before these valves under the cab are tackled?

One last thing, it has a big weight pack on it much of the time and it might do it more with these on. They are off one T8 tractor, so weigh just over 2.5t?

Incidentally there are no error codes

All a bit of a puzzle

 

[michael N123]

newHolland suspension is shite so yours is just normal

 

[Limcrazy]

2016 .......elderly???
All relative I suppose

 

[JohnDeere8530]

2016 .......elderly???
All relative I suppose

well they dont last like they used to

 

[del_boy]

That is a fair bit of weight up front which will be testing the accumulator. 1st thing is to check the accumulator pressure, see if its lost its charge. Just crack the hex nut at the top slightly, if it hisses theres still charge so worth getting the pressures tested, if oil comes out its goosed. This is a 'wearing' part and last typically 2500 to 3000hrs before they need changing .
Also check the wiring loom around the plugs on the right hand side where they come throuh the chassis also check the wiring loom around the fan shroud for any damage

 

[davidroberts30]

Any ideas @Colliedog

 

[cosmagedon]

The 2 solenoids on the valve block under the cab are for up and down, the ones on top of the cylinder are to do with the ride and lockout as far as I'm aware.

We've had similar issues to what you describe but on a older TM, that was the lowering/check valve in the main valve block sticking. This is where I would be looking first, either strip it down and clean or replace the solenoid.

On another note we've had the raise solenoid stick on a T7 and it was constantly pumping up when the tractor was running. That required a new solenoid, the raise/lower solenoids can't be swapped around either as they are different.

 

[cosmagedon]

Another think to check, on each of the 2 solenoids under the cab there are manual screws to raise/lower the suspension. Just make sure these are screwed all the way out.

 

[JohnDeere8530]

many thanks for this. I will check on those solenoid valves under the floor Hopefully they are easy to get to - luckily I have other T7s sitting around so can swap the valves off them

 

[cosmagedon]

many thanks for this. I will check on those solenoid valves under the floor Hopefully they are easy to get to - luckily I have other T7s sitting around so can swap the valves off them

Not the easiest to get at to be honest, if you go under the filter housing with your back to the tyre you can just put your arm up and over the top of the hydraulic pump to get at the solenoids.

 

[JohnDeere8530]

ok thanks, its a job for one of the chaps anyway

 

[2wheels]

in the valve system under the cab there is a small brass filter. it collapsed on our mxm 140 and gave the symptoms you describe. the replacement was a modification.

 

[Colliedog]

Any ideas @Colliedog

Sorry only just got the notification for this. Most of my knowledge is on improving suspension performance rather than repairing them. @cosmagedon is more knowledgeable on repairs. A couple of things to consider is New Holland use a few different types of suspension. 2016 is a change over year to tier4b so yours could have a later dual accumulator set up. These are more advanced and can do funny things if the pressures are low in the accumulators. It is accepted that any hydropneumatic suspension can drop while parked up this will self level as soon as you pull away but it shouldn't drop and stay there in use for no reason. If your accumulator pressures are O.K. then it is most likely to be a valve/connection playing up somewhere.

 

[JohnDeere8530]

many thanks for everyone. I have now looked at it in detail and swapped parts from another T7 and it turns out that there are valve blocks under the cab too, as was mentioned above. It was one of these, luckily the easier of the two to get at. Took it off, blew it out and all seems well at the moment. However, time will tell Once again thankyou for putting me in the right direction