Ford 4000. Slow 3 point hitch lifting

[[email protected]]

Hi, I have a 1969 Ford 4000 3 cylinder diesel, UK build. The pump is in the rear axle housing under the lift cover. Recently I was successfully using a topper (bush hog) on the 3 point linkage. Fairly suddenly, the tractor's hydraulics started lifting really slowly - but they did lift and hold. I took the topper off but the 3 point hitch still lifts really slowly even without a load on it. To diagnose the issue I removed the lift cover and inspected all the O rings between the cylinder and the cover, and under the remote control valve cover. These were all recently replaced and all seemed intact. I did notice that the tube that delivers fluid to the top cover was slightly bent, so I bought a new one with new O rings. This must have got bent at some time when the cover was lifted off at an angle. Anyway, I refitted the top cover, but the hitch still lifts slowly. I checked the fluid levels, OK. I then connected a hydraulic pressure gauge to the remote control cover outlet. With the remote control spool pushed all the way in I got a zero reading. I understand that. With the spool pulled all the way out I got a zero reading. I pushed the spool back in, lifted the 3 point hitch up to the top and left it there and then I pulled the remote spool out again fully. This time I got a reading. So from this, is it correct to assume that the remove implement (if I had one) would only operate if the 3 point hitch was in the raised position? Second question, when the spool was in the middle position I got a zero reading. I thought in the middle position both the 3 point linkage AND the remote implement should both operate? Finally, with the 3 point hitch raised and the remote spool pulled fully out I got a steady reading of 1700 psi. Raising or lowering the revs made no difference, always 1700. I have read that a pressure of 2100 settling down to 1850 is an on-spec reading. So would 1700 psi cause the 3 point hitch to lift slowly? Could the lower than spec psi be due to a worn relief value (I think mine is on the end of the lift cylinder). I've not replaced this yet. So many questions. Thanks for any response. Regards, Tim - UK.

 

[Sean in PA]

Have you tried turning the black knob above the pump on the right side of the center housing? That is the flow control knob, and you might have bumped it at some point. I believe that turning it clockwise is supposed to speed up the flow, but it's been a while since I fiddled with one, so I might be wrong on that.

 

[[email protected]]

Thanks Sean. I have tried fiddling with the flow control knob but it appears to make little difference. Thanks for the response.

 

[Destroked 450]

Did you check the main suction screen for blockage

 

[[email protected]]

Thanks for the response. I think I have a plan now...fully drain fluid, remove lift cover (again!), replace all O rings (again!) But then clean the suction filter and replace the paper element on the return filter, replace the relief valve on bottom of pump and remove and inspect the flow control valve as it doesn't seem to do anything at present. If anyone has any other suggestions while I have the top lid off they would be most welcome. I'm thinking that as the pump is already producing a steady 1700psi there can't be too much wrong with it - can there?

 

[Sean in PA]

How are you testing to se 1700 psi?

 

[[email protected]]

I'm using a 0-5000 PSI pressure gauge connected directly to the remote control outlet plug. This used to feed my front loader but is now capped off. So I removed the cap and used an adapter to connect to the pressure gauge. Pushed the remote control knob fully in to start with. Started tractor and set engine speed to around 1600 RPM. Raised 3 point hitch. Then pulled remote control knob fully out and the gauge immediately read 1700 PSI and stayed steady at that. One thing I may have done wrong was not warming the hyd fluid up enough before testing. Would that make much difference? The manual I have seems to think a PSI reading of 2100-2500 PSI would indicate a working system. Thanks.

 

[sotxbill]

I'm using a 0-5000 PSI pressure gauge connected directly to the remote control outlet plug. This used to feed my front loader but is now capped off. So I removed the cap and used an adapter to connect to the pressure gauge. Pushed the remote control knob fully in to start with. Started tractor and set engine speed to around 1600 RPM. Raised 3 point hitch. Then pulled remote control knob fully out and the gauge immediately read 1700 PSI and stayed steady at that. One thing I may have done wrong was not warming the hyd fluid up enough before testing. Would that make much difference? The manual I have seems to think a PSI reading of 2100-2500 PSI would indicate a working system. Thanks.

Tractor pressure will read highest when cold. As you run it, and the pump is worn, its possible to see even lower readings.. much lower... 1700 is a bit low but not sure you got a" live" check. the asv port works only when the 3point lift is not at the top of travel. As the 3 point activates a "stop" valve at top of travel that cuts off flow to the lift and the asv both. So with 3 pt down... asv all the way out, you should lift the hyd Position lever slowly and see pressure sent to your gauge. Testing warm will show the correct running pressures where testing cold will show high pressure for a few minutes till the fluid warms up and thins down... thus a worn pump will leak thinner fluid more. So testing warm is a must. I have seen 600, 800 and 1200 lbs on worn out pump tests. I would like to see around 2100lbs or higher.. Some tractors as you slowly rev the engine up will slowly climb from an idle up to 2100lbs , then the safety high pressure valve opens and the gauge "vibrates" at 1900 lbs.. and I call that good, barely.

 

[[email protected]]

Thanks for all replies so far. I have decided to try cleaning the hydraulic filters and change the relief valve at the base of the hydraulic pump (gear driven). So far I have removed the flow control valve and the hydraulic pump. I've freed the suction pipe from it's casing mount but cannot get the suction filter out from below the transmission shaft. Anyone have any tips on how best to get this filter out please? It looks pretty gunked up so I'm keen to finish the job. I'm having similar issues with the return filter. I've read that I may have to split the tractor but I really hope that's not necessary.

 

[wackyrig]

I have tried everything to get that screen out. it will not come out without removing the shaft. I dont even recommend unbolting it from the outside because its hard to get lined backup exactly and you risk bending it's mounting brackets when trying to reinstall the pump. unless you plan to split the tractor and remove that shaft in the near future, I would use a pump sprayer full of diesel to blast it clean as best you can, maybe some brake kleen, compressed air and a shopvac and settle for good enough. I nearly created a real problem for myself trying to get that screen out to deep clean it. not worth destroying a discontinued part.

 

[Sean in PA]

I'm pretty sure that splitting the tractor between the transmission and rear axle and then pulling that shaft out is required to get that pickup screen out to clean it properly.

 

[[email protected]]

Thanks Wackyrig and Sean. You've confirmed my thoughts - the screen will not come out unless you split the tractor and remove the PTO shaft. Crazy. I also considered bending the bracket but was worried about it snapping. I did what you advised and cleaned the top part of the screen with diesel and a compressed air nozzle. That did ok but can only guess how good I did the underside. The same issue for the return filter, that's buried well down beyond the PTO clutch. How did Ford ever think that was a good idea. Anyway, I have everything back together now but before I refill and replace the lid I'm going to dismantle the transmission handbrake as that doesn't work too well. Then I'll see if cleaning the filter, changing the relief valve and lift cylinder rings improves the speed of lift. Thanks again for the help.

 

[Sean in PA]

You might also consider filling it to just above the screen with a mixture or diesel and ATF and run the engine for a while. Don't drive the tractor, just run the engine. That pump runs whenever the engine is running and it should flush everything in the 3 point system except for the things that only get fluid while the lift is doing work.

 

[Destroked 450]

Place a short length of hose over the short stand pipe that goes to the lift top, route the hose back into the axle housing to return fluid back into the housing
Add diesel to cover the suction screen about 1/2”, start the engine and let it circulate the diesel thru the system to clean the screen
If this doesn’t clean the screen enough to get good flow a split will be required to remove the screen

The screen on my 4000 was stopped up so bad it collapsed, I replaced it with a external filter system from a 4600

I’d drain the diesel into buckets and if it doesn’t look to bad I’d strain it through a cloth to reuse as fuel

 

[[email protected]]

That sounds a great idea. Do I use ONLY diesel or mix it with tractor fluid? Thanks.

 

[Sean in PA]

Moist folks use a mixture of diesel and ATF. Automatic transmission fluid has a lot of detergent additives and seems to clean that kind of gunk better that most anything else. You won't be able to reuse the diesel afterward, but it will clean things better. Find someone that has a waste oil heater for their shop and donate it to them afterwards.