Ford 7910 back end problems.

[Mattj7910]

Hi all.

Having some reasonably serious problems with our 7910 that we have noticed since it has come off of the forager last Tuesday 19/05/20.

Put it on the flail toper to go and tidy up some rougher gazing paddocks that we rent, after moving the cattle out in the morning. The lift arms are very slow to lift and the spool valves are also very slow on the hydraulic offset and they make a horrible whining noise while using either of them.

Took of the topper, dumped the oil out of the back end and took off both filters. The oil is black and there is a black sediment in the bottom of the drain buckets with a slight silvery metallic look to it, the filters are packed solid with the same stuff. The tractor has 8500 hours on the clock and the oil is super universal and is less than 1000 hours old. The tractor is due the filters changed anyway but last time they were changed there was no sign of this problem, the oil was still golden. All the contamination has occurred in 500 hours and I would say most of it in the last 100.

While the tractor was making silage the driver commented that there was a slight resistance to it rolling freely only noticeable on the road, like the brakes were binding slightly. The tractor had new brake disks fitted at around 7000 hours 6 years ago because the pedals would touch the floor before it would stop you and there was no more thread left on the adjustment, they have not been adjusted for probably 4 years and the adjusting nuts are still locked tight. The biting point of the brakes has not changed and they are still effective.

The tractor always whines a little on the road in 2wd, the same whine you get if you leave the 4wd in on the road just much quieter. With the engine running and the 4wd off, with 1 front wheel jacked off the ground it is impossible to spin that one wheel to line up the hub drain hole level for example.

We have stripped off the axle housings to look at the brakes and they seem to be fine still having hatch marks in the friction material on them, the bottom of the axle housings in coated in a layer of sediment though as well as underneath the diff. It is the same in any corners of the case really.

Dropped off 4wd drop box to check clutch pack, same story there plates look fine but then I suppose they should as they are either engaged or not, they should never be slipping.

As you can tell we have been hunting for friction material braking up and blocking the filters so much to restrict the pumps output.

Having not found anything obvious so far, has anyone here had experience of anything similar, got any thoughts or suggestions?

Any comments welcome.

Will try and attach some pictures later today if anyone is interested.

Thanks in advance.

Matt.

 

[C.J]

PTO clutch ?

 

[Mur Huwcun]

Are all the brake discs in good order including the intermediate (steel) plates? They can warp just enough to drag the brakes. Was the handbrake releasing as it should? Is there any chance it’s been topped up by someone with something else?

 

[Mattj7910]

Brake disks look fine to me, no wear that I can see on the intermediate disks either. Would checking them with a straight edge show the warping? I would have thought handbrake was coming right off, would come by the tool box to hold the tractor with plenty of free clicks before it started to pull up. Would certainly cause the slight dragging feeling though. There are only 2 of us here so I am quite sure it has not had any other oil put in it, we don’t borrow any kit and put on the tractor either.

PTO clutch has already been mentioned as a possible culprit, would it or possible for it to be wearing so fast that is has contaminated the oil and yet there is no detectable slip with the jf900 on the back?

Thanks for your thoughts, the exploration continues.

 

[Mattj7910]

Few more of the brakes and oil

 

[ROBINWORKS]

Check the dual power unit, If same setup as a 6610 there is a small filter in a JIC hyd fitting on the side

 

[startinghandle]

Is oil cooler radiator clear?

 

[yellowbelly]

Brake disks look fine to me, no wear that I can see on the intermediate disks either. Would checking them with a straight edge show the warping? I would have thought handbrake was coming right off, would come by the tool box to hold the tractor with plenty of free clicks before it started to pull up. Would certainly cause the slight dragging feeling though. There are only 2 of us here so I am quite sure it has not had any other oil put in it, we don’t borrow any kit and put on the tractor either.

PTO clutch has already been mentioned as a possible culprit, would it or possible for it to be wearing so fast that is has contaminated the oil and yet there is no detectable slip with the jf900 on the back?

Thanks for your thoughts, the exploration continues.

Nothing looks amiss in that lot.
Looks like the only friction plates you haven't seen are in the dual power.
As that's part of the transmission, maybe that's where your 'slight rolling resistance' is coming from?

Was the dual power working OK?

Sadly, you're going to have to put that lot back together to split it at the clutch so you can get at the dual power.

 

[glasshouse]

Hyd pump

 

[Mattj7910]

Thanks for everyone’s ideas, had a local ex dealership mechanic in on Saturday and he thought hydraulic pump. Pulled the main pump, the one in the back end and stripped it down on the bench. Yes you can see where the gears have been running for 8500 hours but the bushes look in good condition and the gears have not been eating into the aluminium case. Pump still seemed well able to produce pressure to lift an implement was just slow and noisy to do so, leading to the idea of being starved of oil by blocked filters.

Dual power has also been mentioned here, and as that and the PTO clutch are the only things not inspected closely so far I can see the tractor getting split at the clutch and having to check the unit out. Do you have any more detail on where the filter is? You say in a fitting, is that where the pressure feed goes through the bell housing or where it actually joins the dual power unit? Dual power was working well loading trailers behind the forager on some steep banks but then that was in a low gear.

Will have a look at engine mounted pump just in case, as the tractor is in so many pieces already it can’t hurt.

I am still leaning toward it being friction material making the oil so black, my only experience of metal contamination in oil was when the same tractor had one of the bearings break up in the hub on the ZF axle. It ate the seals and leaked on the rim, then when we drained it out the oil was silver full of bearing race and roller not black like this. Happy to listen to anyone’s suggestions though.

Thanks
Matt

 

[Mattj7910]

On the subject of oil cooler radiator being clear do you mean being clear on the outside to draw the air through, or clear in the inside from the sludge in the oil? In any case it is clear enough outside, tractor was not getting hot and was cleaned out before silage. To be honest have not looked in there since have been concentrating on the back end of the tractor too much. Will be sure to have a look tomorrow.

Matt

 

[Bloders]

Is it normal that you cant turn a front wheel when jacked up as described in post 1?

 

[Right-arm fast]

Somebody may have asked but is there a suction screen and or filter to the main hydraulic pump. just wondering if it was a bit choked and starving the pump? Which in turn caused cavitation aerating the oil. You should of pressure and flow tested from the spools before stripping really. To give you a fighting chance of locating the issue.

 

[ROBINWORKS]

Item 11A is the strainer filter for the dual power

 

[Mattj7910]

Yep there is a suction gauze on the main hydraulic pump that has been removed and inspected, there is some larger particles in the gauze but far from blocked. Yea it is looking like some more information about what the pumps were doing would be useful at this point. We don’t have easy access to a pressure and flow tester though and would require getting main dealer involved, might still come to that now mind. If they will come out in to it yet that is with lockdown


I don’t know if it is normal to not be able to turn one front wheel with it off the ground it would be good to know though. That was part of a theory that the 4wd was not disengaging fully leaving the plates binding and wearing and giving the dragging feeling when on the road, from the inspection for the plates there does not seem to be much wear or heat build up on them making that theory seem less likely. Spoke to someone over the phone today and he said about a self locking diff, which would obviously prevent a wheel being turned independently.

I have always wondered about this when chainring the oil in the front hubs, you can’t jack up the axle then spin the wheel and tyre so that the plug is on the bottom to drain it and then spin in level to refill it. You have to drive the tractor until it is in the correct place often requiring 2 people to get right or lots of trips in and out of the cab.

Thanks for the detail on that strainer will pull that out at the first opportunity.

Here are a couple of quick pictures of the main hydraulic pump looking at them now they don’t really show much detail of the case, will try and get some better ones.

Thanks again all.
Matt

 

[ROBINWORKS]

Without the engine running the tractor will probably be in 4wd, Hhnce the reason you are unable spin the wheel fully when the said wheel is in the air ( so to speak).

 

[Mattj7910]

As far as I understand it the 4WD is engaged by spring pressure and is held off by hydraulic pressure, also the solenoid requires power to be in 2WD. So if anything fails you end up in 4WD permanently, therefore the engine needs to be running and the ignition on to power the solenoid to get 2WD. Even in this situation you can't turn the wheel, as in with the wheel jacked up to change the oil in hub, start tractor with switch in 2WD get back out to spin wheel so drain plug is level to refill and I am not physically strong enough to rotate it. You have to do it with the wheel on the ground and drive the tractor. Perhaps this is normal and I am barking up the wrong tree.

 

[agrimax]

You may have a limited slip diff in the front axle. You'd need both front wheels off the ground.

 

[JohnBoy]

Don't know about the cararro but the zf axles at least were limited slip

 

[Mattj7910]

Thanks for the replies will try with both wheels off the ground next time and see what that is like.

Latest on the tractor is, a dealer mechanic came down to confirm a transmission controller fault on our T6.155 as they won't send if off for repair without confirming the fault themselves apparently but thats a different story.

While on the farm he cast his eye over the 7910 and immediately said the brake disks are worn completely out, so with the price of a genuine NH disk now being £16 rather than £42 back in 2014 when they were last done (not sure how that works). A set of disks and all the gaskets have been ordered tractor is going to be put back together, clean oil new filters and be pressure and flow tested. Will then go from there, obviously the brakes will be set up again with the new disks so hopefully it will tell if the dragging feeling goes away as to if the problem was the brakes. Will keep a close eye on the oil to see if it starts to turn black again.

Will repost here with any more developments, as I personally hate it when the story is left un finished and you never know if the problem was solved or not.

Thanks again for all your replies and knowledge.

Matt