3-Point Hitch Ford 6640 3pt hitch problem

[RickB]

No luck. I replaced the broken check valve spring in the remote valve feed line and all the orings on the priority valve. I checked all the spools and they all move freely and there appears to be no grooves or scratches in any of them. I was carefull to put everything back as the book instructed. The pressure came up to about 50 psi and the hitch still doesn't work. The draft control lever seems to work easier though. Deadheading the remotes or loader gives me about 2600 psi on the guage and still doesn't move the hitch. The guage is still connected to the test plug on the main pump (Trailer brake Port). I double checked for an ASC Valve and there is none only a plastic plug on the floor and a pressed in plug on the side of the case. Any other Ideas Rick?? I got prices for a pump that range from online $600 to $1800 from NH. Is there a way to isolate the pump and just check it?? Or do you think I need to get into the rear case? Do I need to order a flow meter or should the pressure guages be enough?

There is a special fitting (Ford/New Holland) that replaces the main pump relief valve and diverts main pump flow to a flow meter. This is the most effective way to test the main pump. Without that fitting, one can flow the remotes and use math to determine whether the main pump is working; if flow is above the GPM of the aux pump, that flow has to come from the main pump. To validate that test, one can fairly easily isolate the flow from the aux pump at the priority pack, flow test the aux pump, and subtract that flow number from the combined total. One way or another, I would get set up to flow test the pump(s) next. As gear pumps are used, engine RPM's are critical when testing. Use the guidelines in the repair manual.

 

[Jackfr]

Hi Mike

Checked for special fitting (special tool) in the service manual and it comes up as a plug D4NN-A574-C and seal E105-GF-9. The Parts guy at NH says it's not a good number anymore and no number crosses to it but he found a plug and seal in the parts book that he thinks will do the same thing or is a replacement for it $12.00. When reading the service manual (Flow Test for tractors without ASC valve option) Part 8 chapter 5 page 18 it says to install a plug allowing the oil to return directly to the reservoir. So is this just a plug in place of the pressure relief valve that allows the oil to flow through the pressure relief valve cavity or is it another special tool/adapter and I'm using the wrong thing again see below.
While looking these up I realized that the Trailer brake adapter (special tool) F0NN-U906-CA $28.00 for pressure testing the pump that goes into the top of the pump is also a special fitting that has a tube with an oring on it that fits down into the pump housing not just a hydraulic hose adapter like I have been using. Possible I have not been getting proper readings because of the wrong connection. I have ordered both from NH and they will probably be here Tuesday. At which time I'll check the pressure again first then do a flow test.
Do you have any ideas where I should buy a flow meter and what I should buy.

Thanks again for your help

Jack

 

[RickB]

The isolation test adapter you are looking for is indeed a sleeve with a seal at the top and bottom O.D. similar to what you are describing for the trailer brake fitting. To find a current part number, someone is most likely going to dig into the service tool catalog and find the cross-reference lists. Many service tool part number supercession chains are incomplete in the parts system. I'd be shocked if you can buy the fitting I have in mind for $12. It may well be that a like tool for a TS90 with the 12x12 transmission will have a more current part number. Verify that the pumps are the same before going all the way down that route, though. Figure at least $300-$350 for a decent flow meter. I put one together from Bailey Hydraulics a few years ago and it has served me well. I can't seem to access their website right now, but I'll check again later.

 

[Jackfr]

Hi Rick

The Trailer brake adapter (special tool) F0NN-U906-CA $28.00 or isolation test adapter came in and I installed it in the top outlet of the pump as the book says. Pump pressure is with in specs 2600 to 2650 psi @ 1200 rpm and 2100 rpm. This is a lot different then using just a hydraulic hose adapter. This will teach me to read more closely and try and acquire special tools when doing tests like this. It would have saved me over a week in time. Anyway the book says if the pressure remains within the 2550 psi to 2650 psi specification it is an indication that the pump does not require an overhaul. My guess would be that if the pump pressure is peaking at 2650 psi then the main pressure relief valve is ok also. I have had the priority valve pack apart and found the spring in the check valve for the remote valve feed line broken and replaced it. This only made the lift control lever move more freely towards the up position. All the spools seemed to move ok with no bad scratches or wear marks. I tried deadheading a remote valve as suggested in the service manual which is suppose to add the auxilary pump to assist in lifting the hitch but that didn't work either. So what's next should I invest $300 in a flow meter or start thinking about taking the top off the case? I know you said I probably could get it off without removing the cab but will I be able to see what's going on inside? I don't think I have the capability of lifting the cab off (to high) for the Boomer. So should I try just jacking the back up and blocking it or think about cutting a large hole in floor under the seat. I'm on duty tonight so I intend on bringing service book with me to read if I have time and will be back in the morning. Any suggestions would be greatly appreciated.

Thanks Jack

One last quick thought. Should I take the priority valve pack back apart and replace all the springs? They all seemed ok when I had it apart before.

 

[RickB]

Hi Rick

The Trailer brake adapter (special tool) F0NN-U906-CA $28.00 or isolation test adapter came in and I installed it in the top outlet of the pump as the book says. Pump pressure is with in specs 2600 to 2650 psi @ 1200 rpm and 2100 rpm. This is a lot different then using just a hydraulic hose adapter. This will teach me to read more closely and try and acquire special tools when doing tests like this. It would have saved me over a week in time. Anyway the book says if the pressure remains within the 2550 psi to 2650 psi specification it is an indication that the pump does not require an overhaul. My guess would be that if the pump pressure is peaking at 2650 psi then the main pressure relief valve is ok also. I have had the priority valve pack apart and found the spring in the check valve for the remote valve feed line broken and replaced it. This only made the lift control lever move more freely towards the up position. All the spools seemed to move ok with no bad scratches or wear marks. I tried deadheading a remote valve as suggested in the service manual which is suppose to add the auxilary pump to assist in lifting the hitch but that didn't work either. So what's next should I invest $300 in a flow meter or start thinking about taking the top off the case? I know you said I probably could get it off without removing the cab but will I be able to see what's going on inside? I don't think I have the capability of lifting the cab off (to high) for the Boomer. So should I try just jacking the back up and blocking it or think about cutting a large hole in floor under the seat. I'm on duty tonight so I intend on bringing service book with me to read if I have time and will be back in the morning. Any suggestions would be greatly appreciated.

Thanks Jack

One last quick thought. Should I take the priority valve pack back apart and replace all the springs? They all seemed ok when I had it apart before.

If the rear pump is developing >2500psi, the hitch should move if that oil gets to the lift piston. I guess I'd think about pulling the lift cover. The control valve will come off with the cover, there won't be much of anything to see in the rear axle center section except the differential. The manual will be more help than I on the control valve, I haven't had a 4 cylinder 10 or 40 series hitch cover off (yet). Hope you get this sorted out soon.

 

[Jackfr]

Took the hitch cover off without moving the cab. We used bucket forks on the boomer and slid them under the lift arms there is just enough room to get the cover out. Putting it back together might be a different story though any ideas on that. We found the return oil pipe from the priority valve pack broken and the lift linkage bent and apart with an eclip missing. I'm going to try and straighten it in the morning but some parts that are bent appear to be cast they might need to be replaced. I had to remove the piston to get to the return tube. Should I be checking anything else or just fix the linkage problem and then back together. I know if I get into the piston and it's spool valves it gets into some lengthy setup procedures. I need to have a parts list together early tomorro for a Saturday delivery.

Jack

 

[RickB]

I'd make the necessary repairs to the bent and broken parts. Replace all the O-rings and seals you have disturbed, including the piston seal and re-assemble.

 

[Jackfr]

I think I have found what caused the damage to the internal linkage. The top link shaft has a keyway in it where it enters the inside of the cover. There is a 7/16" special bolt that bolts a bracket onto the cover and goes thru and locks the keyway so the top shaft will not rotate only go in and out operating the draft control linkage. The very end of the bolt has a shoulder turned on it so it will fit into the keyway. The shoulder was worn down causing the shaft to rotate bending and breaking erings off the the linkage. Found this bolt by accident. I have ordered it next day Sat delivery along with all gaskets orings seals and piston seals. I was able to straighten the bent linkage and it all appears to be working fine now with no binding as long as that rear top link shaft doesn't rotate. I hope to have it back together today or tomorro as I have help next two days. I'm back on duty Monday and Tuesday so next day I can work on it is Wednesday with no help.

 

[Soundguy]

Thanks for the update, and good job sluething out a possible cause of the damage.

keep us posted, and we will keep our fingers crossed for you.

soundguy

 

[Jackfr]

Well it's back together and working fine thanks for all your help. We finished putting it together tonight about 7:00 pm. Its actually woirking better then anytime that I have owned it. so this must have been going bad for a long time.

Thanks again

Jack