641 Power Steering Conundrum - 2nd Verse

UseFixUse

Member
Below is a link to the 1st verse. I'm still working on the PS issue with no diagnosis yet. Thanks very much for any help. I hope this link works.
http://forums.yesterdaystractors.com/viewtopic.php?t=1054764
 
your link didn't work. But a search found it. Have you tried turning the steering wheel with the front wheels jacked up in the air? That may tell you if everything is working just too weakly?

Joe
 
Another thing you can try. Jack up the front end. Disconnect the PS cylinders from front of the drag links. Tie them in place. Then start the tractor. Turn the steering wheel back and forth. What happens can point you in the right direction. No movement out of the cylinders - you are not getting pressure to the cylinders. Wrong direction movement - the hoses are backwards. Erratic movement is probably a problem with the steering valve -likely springs.

Worth a try.
 
Thanks guys. With the engine running, when I lift the front wheels off the ground with the loader, I can steer the wheels side to side easily. I then disconnected the fronts of the cylinders from the drag links. With the engine running, I can only turn the steering wheel slightly either way but when I do, the rods on both cylinders move very slowly in the proper directions. I rechecked the valve assembly and the springs, plungers and balls are fine. Am I looking at a weak pump? Thank you for your replies.
 
My bad. I disconnected the cylinder rods from the drag links and tried to turn the steering wheel with the front wheels ON the floor. Of course the steering wheel was hard to move. I will test it with the front wheels OFF the floor today and post my results. Thanks.
 
Gentlemen, with the front of the cylinders disconnected from the drag links I started the engine, raised the front tires using the loader and easily cranked the steering wheel side to side. The cylinder rods barely moved but they did move in the correct direction. Earlier when I clamped a hose to the output of the PS pump, pulled the coil wire and cranked the engine, fluid squirted out the hose but couldn't tell if it was just volume without pressure. thanks.
 
I'm starting to think pump like you are. Which pump do you have, the Ford Piston Pump or the Eaton rotary pump? Do you have any way to plumb in a pressure gauge?
 
(quoted from post at 13:48:53 09/15/13) Gentlemen, with the front of the cylinders disconnected from the drag links I started the engine, raised the front tires using the loader and easily cranked the steering wheel side to side. The cylinder rods barely moved but they did move in the correct direction. Earlier when I clamped a hose to the output of the PS pump, pulled the coil wire and cranked the engine, fluid squirted out the hose but couldn't tell if it was just volume without pressure. thanks.

Yet you were able to lift the front up using the loader?
 
Kurt-NEPA-- It is a roller vane PS pump with the reservoir on top. Yep, a pressure test would be the definitive test, I guess. I'm wondering if I should have a shop make a test hose with a tee for a gauge? Do you know a better way?
Michaels Dad--The loader hydraulic system is independent of the PS system. I detached the steering cylinder rods from the drag links to test them, then used the loader system to lift the front wheels.
Thanks.
 
(quoted from post at 14:39:51 09/15/13)
(quoted from post at 13:48:53 09/15/13) Gentlemen, with the front of the cylinders disconnected from the drag links I started the engine, raised the front tires using the loader and easily cranked the steering wheel side to side. The cylinder rods barely moved but they did move in the correct direction. Earlier when I clamped a hose to the output of the PS pump, pulled the coil wire and cranked the engine, fluid squirted out the hose but couldn't tell if it was just volume without pressure. thanks.

Yet you were able to lift the front up using the loader?

I don't understand your question. The loader should be on a separate pump from the power steering, so the loader being able to lift the front end off the ground should have nothing to do with his power steering problems.
 
(quoted from post at 18:45:38 09/15/13)
(quoted from post at 14:39:51 09/15/13)
(quoted from post at 13:48:53 09/15/13) Gentlemen, with the front of the cylinders disconnected from the drag links I started the engine, raised the front tires using the loader and easily cranked the steering wheel side to side. The cylinder rods barely moved but they did move in the correct direction. Earlier when I clamped a hose to the output of the PS pump, pulled the coil wire and cranked the engine, fluid squirted out the hose but couldn't tell if it was just volume without pressure. thanks.

Yet you were able to lift the front up using the loader?

I don't understand your question. The loader should be on a separate pump from the power steering, so the loader being able to lift the front end off the ground should have nothing to do with his power steering problems.

I had a senior moment. Thanks for waking me up.
 
Thanks for the replies.
Would the following be the simplest design for pressure testing a PS pump?
From the output of the pump, plumb a line that has a tee for a gauge, then an inline valve, then a hose for directing the fluid into a bucket or back to the return port of the reservoir. Next, starting with a full reservoir of fluid, pull the coil wire and have someone crank the starter while I slowly turn down the valve (never closing it completely) and observe the gauge. My 12 volt system turns the starter pretty fast but if it's not fast enough, I could briefly start the engine. Thanks.
 
I'm going to step out of my experience and throw this out for what its worth. Maybe someone can confirm it. Most of the power steering pumps I have worked on (Eaton pumps) have a built in pressure relieve valve. If your Ford (prob Vickers) vane pump has one, it should be safe to just to tee in a gauge on the pressure line and start the tractor. The pressure should come up to about 700-1000 psi and stay there.

I think you'll have problems trying to find parts for the vane pump. Eaton pumps are much more common. I would start searching bone yards for a donor. Make sure to get all the brackets, reservoirs, caps and fittings. Eaton pumps rarely go bad except to blow a seal. The seals can be replaced and rebuilt pumps are available.

Photo of an Eaton pump on a 660.

 
Thanks for the picture Kurt-NEPA. Here is a picture of my 641 PS pump. The outside looks like your pic of an Eaton pump. When I opened mine up, the inside matched the guts of a roller vane pump on page 35 of the I&T Shop Service Manual.
Did the Eaton and the Roller Vane pump have similar exterior?
Also, as far as pressure testing, I will probably order a pressure gauge (0-2,000psi) and try to cobble together plumbing to test the PS pump output. I hear ford brake line may help. Thanks for your input.
mvphoto20685.jpg
 
Thanks a lot, Kurt-NEPA, for your input and the link to the Eaton pumps rebuilding site. Lots of good info on that site. I have ordered a 0-2000 psi gauge and will then build some plumbing around it so I can start ruling out components starting with the PS pump.
Just to be sure, the photo is of an Eaton pump, right?
Thanks again.
mvphoto20825.jpg
 
Gentlemen, my new gauge arrived so I plumbed it into the pressure side of the power steering pump. I found zero psi with a faint flicker on the first rev of the pump. I figured bad pressure relief valve or bad pump. I pulled and dissembled the pump, clamped the shaft in a rubber jawed vice and hand-torqued the roller carrier and found that I could turn it on the shaft. It turns out the drive-key had worn and allowed the shaft to spin free. It had also hollowed out one side of the keyway in the roller-carrier. I ordered a roller-carrier and drive-key. I'll report on what I hope will be the final verse of my first adventure into power steering repair. Thanks again for all the advice and observations.
mvphoto20966.jpg
 
Wow!, at least you found the problem.

Have you seen the "How To" on the other Club site for N Tractors. Can't link to it here, but if you look under the How-To's there you'll see it. He successfully used a rebuilt pump off an early Mustang. Reasonably priced too.

If you can't find it, send me an email and I'll send you a copy. My email is open on the Modern side of this forum.
 
Thank you for the site referral. I just went there and found a world of information. These great clubs and people willing to share time and information helps me worry a little less about breaking something on the old machinery.
 
Glad to hear you found it. You are right, lots of info and help both there and here.

Keep us posted on your progress. We all learn from each other.
 
I finally had time to get back to my baby in the shop. The roller-carrier and drive-key had been delivered so I carefully washed the innards of the Eaton PS pump in solvent, then dipped them in 134 oil before assembling them. The only assembly advice I can offer anyone doing this is to be very careful when inserting the lubricated drive shaft through the seal. The sharp change in diameter on the shaft wants to catch the inside of the seal. Try inserting the shaft from the other side.
I reinstalled the pump, filled it with 134 oil and started the engine. Power steering never felt so good! It works better than ever before!
On a side note, for anyone interested, as suggested in an earlier post to me, I don't think it makes any difference which side is up on the spool in the control valve, at least on my 1961 Model 641.
Thanks very much for all the advice. It made my first PS adventure less frustrating and more fun.
 

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