My F-1700 testing my patience

[Texas Blues]

Might want to check the lift piston seal. Its pretty easy to remove. The lip seal can crumble into little pieces. Jc has some nice pics when he did his piston seal. I changed mine, and it makes a world of difference (assuming you have good pump pressure). Good Luck TB

 

[JC-jetro]

J

One last thing - I did buy a new seal for the pump, but did not install it. Do you have a good procedure to change it.

Thanks
Andy

Andy,

I'm swamped at work today, I'll answer your questions as soon as I get some free time hopefully later this afternoon, I might have a few suggestions that could help.

JC,

 

[JC-jetro]

J.C. I have been having trouble with my 1700 hydraulics too and have cleaned the filter repeatedly and changed the oil a couple of times and made sure I got all the old gunk out of the differential and after I use the tractor for a couple of rounds of mowing, the hydraulic pressure goes down and I am dragging my brushhog. I have to let it cool down and then take it back to the barn!
I was inspired by your article and bought the seal kit thinking that might solve my problem and I took the pump off and tore it all apart and replaced the seals and now it has NO pressure and I thought I let it run long enough that it should have been primed like you mentioned.

I have a few of questions.
1) Are the seals to be flat side down? If not they didn't seam to fit flush. I couldn't find my manual. Didn't know if this might be the problem or not.
2) The pump seemed hard to turn by hand after I put it back together and tightened up the screws. I did not check it before I tore it down to see how free it was. Why do you think it was hard to turn? It got hard when I tightened up the allen head screws. Do they have a specified torque?
3) I was going to get a pressure gauge and test the pressure just to see how much pressure it was making if any. Can you tell me what size the fitting is needed to attach the hose and I read in another post that I needed a gauge that would read 3K PSI. I assume I would need a special hydraulic hose for the gauge too?
ALso NH sold me the wrong gasket for the pump. I have a square one and they sold me a round one, but was 75 miles from the dealer so I used the old one. It was not in bad shape. Do you know if there are different series pumps and gaskets?

One last thing - I did buy a new seal for the pump, but did not install it. Do you have a good procedure to change it.

Thanks
Andy

Andy,

Here we go.In order to figure out pump operation you need to know pressure and volume of fluid being pumped. 2000 psi @ .5 gpm is not the same as 2000 psi @ 7.0 gpm. By cleaning the screen, gunk in the differential you removed some of blockage or all of it at the pump inlet. intake Blockage causes cavitation that is the same as gasping for air and gurgling only here it is oil that we talk about. A hydraulic gear pump is a positive displacement pump rather than a centrifugal so it can suck up oil up to a point provided the pump seals are working and very close tolerance between gear and pump case is maintained. What you need to do is to figure out if your pump is working or not, as far as flow you can take the banjo fitting at the pump discharge and run the tractor to see if pump can flow trying to collect the oil in to a bucket. I don't recommend it as it can be pretty nasty to clean up the mess. You can measure the pump discharge pressure as the picture below shows. You might not read pressure there if lift spool valve diverts all the flow back the diffy (highly unlikely). I bought my pressure gage from Northen under $15 and it is a good thing to have. it is I believe 1/4" NTP, take a plug out of where I put the gage to figure out reducing bushing size. can't remember it from the top of my head. Now back to your questions.


1- The nylon lift piston seal is double lipped (U shaped). The seal should be installed in a manner that the pressure expands the outer lip against the cylinder wall. I add a pic here on my busted seal and it shows the correct orientation. It does not need to be flush. When the oil pressure enters the cylinder it expands the lip outward toward the cylinder wall. Keep the nylon seal lubed, you might set it out in the sun for a few minutes and it expand, don't direct heat it. Keep it on the piston as square as you can, make sure orientation is right and work it in, don't use any thing to pry the lip. It will fit snugly. it is a one time deal, you'll destroy the seal if you try again.






2- When I did mine I put a witness mark on all 3 pieces of pump assembly so I can put it back just exactly it was, that also includes the 4 bushings in the pump middle section. The reason for that is that tolerances are very tight and there are minute amount of wear happens before all the pieces are fitted together when the pump is new and i did not want to change that. Make sure I have everything perfectly clean and put a film of hyd oil on all pieces when you fit them together and never use force, it can be tight. By hand pressure you can turn the pump shaft after you put the gear back on the shaft but it will be hard. There is not a torque setting that I know but make sure you criss cross tighten the allen heads. In my case my pump seal looked okay but the main pump shaft seal was bad and dry. That is not part of the overhaul kit and you need to buy separately @ about $10 if I remember it right.









3- Kind of mentioned the gage above. Yes , 3000 psi is what you need. Your operating pressure is under 2500 psi (adjustable) . I set mine to about 2000 lbs and it lifts all the implement I have.




Again your issue might be the shaft seal and not the rest. Although mine looked good I replaced all the seals including the shaft seal. I would use exactly the gasket kit I need since the design follows special geometric shape of bushing. The gasket does have a rubber and a nylon components as well. I will post a pic for clarity.




Like I said above keep it as clean as you can , I took engraver and put witness mark all all the mating part, between 3 section of pump case, pump case and the bushing to make sure I put everything back just like it was. Lubricate all well , do it all on a clean towel and tighten all nice and slow, don't force anything and don't beat things to submission. If you lube the bushing well still it can be tight and that's a good thing. If gear against the casing is loose then you will not develop pressure and have plenty of blow by.


Good luck and post back with your result.

JC,

 

[andreww]

Thanks JC - I will have to get that gauge and the piston seal and tear into it again. What concerns me is that I did have hydraulic pressure before I replaced the seals in the pump and now I can't seem to raise enough pressure to lift my brush hog or the loader.

I never measered the pressure before I tore into it and thought the seals were bad since it lost pressure when it got hot.

Would the shaft seal lose pressure and not lose fluid? I never saw any leak there before.

On changing the shaft seal. What procedure do you use to do that? I was afraid I would bugger up the shaft by trying to hold pressure on it to take the nut off the shaft.

Also it may be a couple of weeks till I get back to this project as my tractor is at my lake place.

Thanks again, Andy

 

[JC-jetro]

Thanks JC - I will have to get that gauge and the piston seal and tear into it again. What concerns me is that I did have hydraulic pressure before I replaced the seals in the pump and now I can't seem to raise enough pressure to lift my brush hog or the loader.

I never measered the pressure before I tore into it and thought the seals were bad since it lost pressure when it got hot.

Would the shaft seal lose pressure and not lose fluid? I never saw any leak there before.

On changing the shaft seal. What procedure do you use to do that? I was afraid I would bugger up the shaft by trying to hold pressure on it to take the nut off the shaft.

Also it may be a couple of weeks till I get back to this project as my tractor is at my lake place.

Thanks again, Andy

Andy,

First order of business should have been establishment of pressure and flow without pump dis assembly, a bit late for that though. The inlet and outlet configuration on 1700 pumps looks identical, but I believe the pump shaft was on the inlet side rather than on discharge side. I had no hyd fluid in the crankcase. Guys reported leaking oil (hyd) in to crankcase on many occasions as well but not on 1700. Anyhow you would not see oil leaking out exterior to tractor . it will be internal.

it is essential you do not score the pump shaft in any form during the dis assembly. It can be done quite safely. I would use two piece of 1" thick pieces of wood, sandwich the pump gear in between the pieces of wood on a bench vise nice and secure . The gear teeth would dig in to the wood firmly. With the gear secured I would take the nut off (CCW). I would then use a harmonic balance remover to pull the gear off of the shaft.There is a snap ring that holds the shaft seal in place, take an automotive snap ring tool to remove the ring. Remover the pump case 3 pieces and simply push the shaft down out of the hole. The seal will stay where it is. Remove the seal by prying or pushing from behind. The seal lips should face internally along with the spring that keeps the seal very tight against the shaft. Make sure to put the shaft key during the assembly. Make sure everything is perfectly clean and lubed during the assembly. it is a one time deal. it is essential that you do not nick the lips of pump shaft seal. Make sure to put the snap ring back. I would tighten the nut with the same procedure as the pump shaft can turn and there is no way to keep it from turning other than grabbing the gear in a vise.






Good luck,
JC

 

[oldford1700]

Well, this tractor is giving me a run for the money. I like to take up a challenge every once in a while but this thing is keeping on giving me a new one just too frequently .
Just quick excerpts.
Bought a 1979 Ford 1700 (First time owner, pretty green )in good mechanical shape (anything that naked eye could confirm), No rust , kept inside , engine started right up, no oil burning, 3 point hitch worked ( went up and down as commanded and stayed where I told it to stay). I changed all the fluid but transmission/Hydraulics and lubed it good. Bought a carry all, put floor and side and took it to the field. It worked great for a while, .but then,?


First problem: 3 point started act squirrelly, would not go up or down as commanded, would decide on its own when to do it, I checked relief off the pump discharge and the lift piston and all checked out. Checked the inlet screen on pump intake and it was badly clogged with residue of old oil (20 years) and no metal shaving. I cleaned the screen , put all togetehr with new oil and she perked right up to the point I did my first project of making 3-point boom and went to the field. I ended up having all kind of power and started having fun. Pulling a six inch 40 yr old post was like pulling tooth pick our of butter.





Second problem: Unfortunately my elation was short lived. I had all the hydraulics power when the engine was running but as soon as I turned the engine off the 3 point would go limp on me quickly. I reckoned I had a leak of some sort internally in areas such as relief valve, spool valve or piston seal. First two checked out okay. I took the cylinder head off, removed the lift cylinder and piston and ç*ºoila piston seal had seen better days. I'm sure that is the original 20 year seal. Any how, changed the seal, put all together and start the tractor and 3 point promptly comes up and stays up with the engine shut. I turn the engine on again, and up and down we go and, she responds quickly. I go to the field and work for 6 Hours and keep hauling and skidding lumber. After lunch I lower it a tad bit to load something heavy, she comes down but when I tried to rise her back, she refused with no inclination to even try. I did not like that a bit. Refrained to lower 3 point any further as I needed to take the tractor back to the barn with the cargo.






The fact that hitch stays up when I ask it indicates to me that piston seal installation is done right, spool valve holds tight and piston relief is not prematurely opening up. I went to the barn a bit gloomy, checkd the relief valve for some restriction and itç—´ okay, open up the pressure relief port (on pistion head) by taking the valve body and all and then started the engine, dang no oil coming out with engine running. Then I took the relief assembly on pump discharge pumping out , put a bucket undeneeth and started the tractor. I do get some flow but can not quantify pump flow or pressure quality of the oil. At this point, I think the seal on the pump that is the same vintage of the lift cylinder has come to the same fate, and the reason I had some flow is just gears doing some pumping with no back pressure. I think the pump had to battle more of restriction and copuld not cope having seals probably sma shape of piston seal and for sure the same age.




I have ordered the pump seal kit and looking for some free time to get the pump overhauled. Can anyone chime in with some word of wisdom? I reckon I have done everything in a logical manner and nothing I have done could have caused the problem. I also think may be with new piston seal the pump had to content with more pressure and gave out but æ»´ow come I could lift the post out of the ground with the same pump without a peep?ç´�/QUOTE]

Found this. I'm not taking your bet on the seal - I bet you are right. But it looks too easy.

 

[JC-jetro]

Found this. I'm not taking your bet on the seal - I bet you are right. But it looks too easy.

It's a piece of cake....Crumb cake that is

JC

 

[barbqranch]

Any chance your hydraulic filter is clogged again?

 

[oldford1700]

Any chance your hydraulic filter is clogged again?

It was the seal. I found it all in pieces when I pulled it out. Working great now.

 

[oldford1700]

As usual you were right on the money JC. Up and running better than ever after seal replacement.