Ford 1700 Dead headed hydraulic pump- am I screwed?

[toukow]

I'm a novice. I was trying to hook up a three point backhoe to which I've extended the lines 10 feet to help get it into position. I'm standing there and hear the sound of the tractor change. I look around and find one of the extension hoses has fallen off. Things seem jerky on the backhoe so figured it had a problem, so I quit and disconnect the backhoe, and reconnect the tractor as usual. Now the with the backhoe separated, the hydraulics hardly work on the tractor. Bucket barely lifts after a while.

Question: Have I broken a golden rule of tractors by dead heading the hydraulic pump? Your comments appreciated. Thanks, Dean

 

[Wolfy]

If the backhoe sat for a while, it might have been real low on fluid. So the tractor fluid might have filled up the backhoe, leaving the tractor empty.

 

[jix]

If the backhoe sat for a while, it might have been real low on fluid. So the tractor fluid might have filled up the backhoe, leaving the tractor empty.

Most likely that is the problem..Can You check the fluid reservoir? Don't run the hydraulic pump empty too much either

 

[toukow]

Most likely that is the problem..Can You check the fluid reservoir? Don't run the hydraulic pump empty too much either

I will check the reservoir, but believe the sound out of the tractor was directly related to the hose supply from the tractor to the backhoe disconnecting while in service. The tractor holds something like 5 gallons of fluid, so I would have thought it fine. I'll also do a pressure test tonight. I was worried that dead heading a pump like this was a mistake, even though I think it only happened for 90 seconds or so. Dean

 

[JC-jetro]

How about your main hydraulic pressure relief device ? how is your backhoe plumbed ? Dead head on Positive displacement is always bad unless the flow is safely diverted by means of relief device. oil trapped between the gears on your pump have to be able to go somewhere as liq is not compressible. You can dead head a centrifugal pump for a few minutes at most without damage as the impeller can freewheel.

JC,

 

[toukow]

How about your main hydraulic pressure relief device ? how is your backhoe plumbed ? Dead head on Positive displacement is always bad unless the flow is safely diverted by means of relief device. oil trapped between the gears on your pump have to be able to go somewhere as liq is not compressible. You can dead head a centrifugal pump for a few minutes at most without damage as the impeller can freewheel.

JC,

Thanks JC for responding. Your posts have been very helpful to me in the past. I just tested the pressure with a 0-5000 PSI gauge at the location you showed and it reads zero. You had stated in the other thread 'You might not read pressure there if lift spool valve diverts all the flow back the diffy (highly unlikely)'. I assume this is if you have a defective three point lift, which I was using at the time. But given the sound change of the tractor, 90 seconds or so elapsed time, and a brief smell of a hot something, I'm guessing I damaged the pump.

I don't know much about hydraulics, but here is my as-built description of the system. Please correct any incorrect terms I may use. Somehow I think my term 'low pressure return" is inaccurate, but I've attempted to document as best I can.

As I show in the photos, it appears to:
1. Leave a high pressure port to the loader valve from under the driver's seat, then returns from the valve to the fitting as noted in the photo.
2. Off of the loader valve, I had installed a 'Power beyond fitting', and this goes to the backhoe, and from there returning to the same return fitting as stated under item 1.

I have read your other post on the pump rebuild, but only maybe 20% of the photos remain in the thread, which is unfortunate.

I will pull it off tonight, and disassemble enough to inspect. They don't show much inside the pump on the parts breakdown. I thought you mentioned you had to buy a seal kit too. From looking at Messicks, I think I need to buy

Object moved

31 SEAL KIT Hydraulic Pump Seal, Interior, See Service Bulletin 3-82, No Exterior Seal Kit Available, Start Year: 01-JAN-79 SBA340490157

1A SEAL PROTECTION Seal, Oil, for Pump Drive Shaft, Start Year: 01-JAN-79 SBA340490151

If it's too wasted, I guess its replacement time. Thanks, Dean

 

[JC-jetro]

Dean,

- Reading zero pressure is not a good sign but it is not entirely conclusive that your pump is bad. Where you read the pressure on the lift cylinder head is down stream of pressure relief device and or your lift spool valve. If either one divert flow to the diffy then pressure will be low but yo should read some residual pressure.
- You need to follow from your hyd pump discharge (pressure, smaller dia pipe) till it attaches to your relief device. You need to remove the cap where you will find spring and a conical poppet valve that set system pressure based on stiffness of the spring. Stiffens on some like my rig can be adjusted by tightening or loosening a nut and in some by adding or subtracting washers, shims. if you dead head the pump the valve will be lifted off the seat, Chartres and floe is diverted to the diffy without damaging your pump.
- make sure to check hyd oil level start the tractor with relief port open to see if you get any flow and report back. Limit running it to no more than 30 seconds.
-if you suction line(larger dia) is blocked then the pump can cavitation and not pump anything. the terms LPR is okay to use as returned or unused oil will be diverted to an atmospheric vented vessels (Ie. diffy) so pressure is dissipated quickly.
- I used to use a picture hosting service and they changed their policies and limited free hosting to only 1000 pic and as a result I lost some random pictures. I can re-post them on another site without restriction if it will help you later on. Let's find your problem step by step.
- Tolerance between gears against each other and the pump case is very tight, heat or lack if lubrication can damage the pump or reduce it'd pumping efficient in nothing flat. Overhaul is not difficult and consumable for the repair was pretty easy to find from NH dealer. I think my kit was under $50 and another seal for input shaft under $10 .
- does you back hoe has a relief device?

Let's do the flow test before attempting to take the pump off. You put witness mark on the pump that is made of 3 compartments. you want to separate them slowly , carefully and as clean as you can. Take photos of how seals go in so you would not damage new parts.

Let me know if you want the pics and I'll re post them.

JC,


ps. look at the link below. some pics are still there. stupid Imageshack has all my pictures but wants me to get premium to be able to be posted.

http://www.tractorbynet.com/forums/...ng/90819-my-f-1700-testing-my.html?highlight=

 

[toukow]

Dean,

- .....Where you read the pressure on the lift cylinder head is down stream of pressure relief device and or your lift spool valve. If either one divert flow to the diffy then pressure will be low but yo should read some residual pressure.
- You need to follow from your hyd pump discharge (pressure, smaller dia pipe) till it attaches to your relief device. You need to remove the cap where you will find spring and a conical poppet valve that set system pressure based on stiffness of the spring. Stiffens on some like my rig can be adjusted by tightening or loosening a nut and in some by adding or subtracting washers, shims. if you dead head the pump the valve will be lifted off the seat, Chartres and floe is diverted to the diffy without damaging your pump.
- make sure to check hyd oil level start the tractor with relief port open to see if you get any flow and report back. Limit running it to no more than 30 seconds.
,,,,,, the terms LPR is okay to use as returned or unused oil will be diverted to an atmospheric vented vessels (Ie. diffy) so pressure is dissipated quickly.
-

Let's do the flow test before attempting to take the pump off. You put witness mark on the pump that is made of 3 compartments. you want to separate them slowly , carefully and as clean as you can. Take photos of how seals go in so you would not damage new parts.



JC,

Thanks for suggesting I go step by step on this. I need to study this more, because when I look at the attached layout of my system, and if the power beyond is simply passing high pressure fluid through the loader valve, it would seem the fluid is going directly back to the tranny, which isn't pressurized. It would appear that the system would be unable to maintain any pressure in the lines as there would be no back pressure if it were as I describe, so I'm missing something.

EDIT: I think I see now. There is little pressure in the system when action is not being called for by the operator. When he actuates a device, it blocks off the return path to the tranny building pressure, and directs it to a cylinder to do work. When he lets go of the control lever, the pressure again drops and just flows in a loop, unless you're stupid enough to disconnect the quick connect which is part of the return. Am I looking at this correctly?

So If I'm understanding your logic, you want to rule out that the pressure relief valve actuated due to the backhoe quick disconnect coming apart, but then the pressure relief valve failed to reseat?

I said zero pressure, but there is enough for the loader to lift after holding the loader valve lever for a bit. Does that remove the need for the test stated next?

So you want me to remove the nut and valve underneath at the location of the arrow in the attached photo, right? Then start the tractor and see if I have flow? I will check the level, and try this when it won't bother the neighbors later this morning, and post back.

As to the photos, yes that is the thread I was referencing. Whether I use them or not (and I hope NOT to need them), I think the thread and your significant effort(s) are valuable, and you should reload when you have time. I know, easy for me to say! I believe they can be loaded directly via the forum software, with no intermediary service involved. There may be a limit of storage on the forum, but usually an administrator will increase your storage allotment for valuable contributions. At least that has been my experience. Or dump photos from less detailed and valuable threads. My two cents.

I thought your approach of using an engraving tool to make the witness marks pretty slick. I may buy one sometime just for that purpose. Thanks, I appreciate your time and advice- Dean

 

[JC-jetro]

Thanks for suggesting I go step by step on this. I need to study this more, because when I look at the attached layout of my system, and if the power beyond is simply passing high pressure fluid through the loader valve, it would seem the fluid is going directly back to the tranny, which isn't pressurized. It would appear that the system would be unable to maintain any pressure in the lines as there would be no back pressure if it were as I describe, so I'm missing something.

EDIT: I think I see now. There is little pressure in the system when action is not being called for by the operator. When he actuates a device, it blocks off the return path to the tranny building pressure, and directs it to a cylinder to do work. When he lets go of the control lever, the pressure again drops and just flows in a loop, unless you're stupid enough to disconnect the quick connect which is part of the return. Am I looking at this correctly?

So If I'm understanding your logic, you want to rule out that the pressure relief valve actuated due to the backhoe quick disconnect coming apart, but then the pressure relief valve failed to reseat?

I said zero pressure, but there is enough for the loader to lift after holding the loader valve lever for a bit. Does that remove the need for the test stated next?

So you want me to remove the nut and valve underneath at the location of the arrow in the attached photo, right? Then start the tractor and see if I have flow? I will check the level, and try this when it won't bother the neighbors later this morning, and post back.

As to the photos, yes that is the thread I was referencing. Whether I use them or not (and I hope NOT to need them), I think the thread and your significant effort(s) are valuable, and you should reload when you have time. I know, easy for me to say! I believe they can be loaded directly via the forum software, with no intermediary service involved. There may be a limit of storage on the forum, but usually an administrator will increase your storage allotment for valuable contributions. At least that has been my experience. Or dump photos from less detailed and valuable threads. My two cents.

I thought your approach of using an engraving tool to make the witness marks pretty slick. I may buy one sometime just for that purpose. Thanks, I appreciate your time and advice- Dean

<img src="http://www.tractorbynet.com/forums/attachment.php?attachmentid=395194"/><img src="http://www.tractorbynet.com/forums/attachment.php?attachmentid=395195"/>

Yes on test of flow. I'm heading out. Will respond later.

 

[toukow]

JC: YOU SIR ARE A SAVIOR!!
I checked the fluid level and it was fine.
Connected a 0- 140 PSI pressure gauge and ran it- had zero PSI as I stated earlier.
Pulled out the pressure relief valve component, and started the tractor for 6 seconds, as fluid went all over. NOTE: I'm glad I had put down plastic sheeting for this test just in case.
Reassembled the valve. At first I started the valve back into place, but was concerned the poppet might fall off the spring into which it fits. So I took it out and put some grease on it to secure it in place while screwing it in.
Started the tractor- operated perfectly.
I then performed the pressure test per the manual, and had 1900 PSI, and adjusted the pressure relief valve to 2100 per the Ford manual value of 2133 +/- 71 PSI. So I'm assuming the poppet valve was stuck out of position as you surmised. Still would have thought would have had some pressure, not zero, but that wasn't the case.

Q1. My 'EDIT' statement above is incorrect, right? What approx. pressure would I see if I put the gauge at the return fitting at the tranny/control valve? Would it be near zero or?
Q2. For the system I drew above, a properly operating pressure relief valve will protect the hyd. pump from people like me, right?
Q3. Will your 1700 start on a 60 degree day without using the pre-heat?

Thanks very much for help!- Dean