Ford 641 power steering

FarmerJeff1550 · Jul 9, 2012

I'm working on a 641 for the neighbor and we found the that the steering control valve was shot, I replaced it and all the seals in the gear box and that is fine. The tractor turns to right very good but turning to the left is hard. I have bled all the fluid out of the two cylinders and purged all the air out of the system and filled with new hydraulic fluid still the same thing.

I have double checked the bearing not in the control valve and it is fine. I jacked up the front end and it is the same. I am thinking that one or both cylinder tubes may have ballooned because with the cylinders unhooked at the rod end, they are go faster towards the end of the stroke then they do in the middle of the stroke. I do know that the valve and cylinders get pretty hot to the touch after running it for about 5 minutes.

Any ideas? I do not have the means to check the cylinder for ballooning or a bad piston without tearing it apart so I found a shop that will check it but they are wanting some cash so I wanted to hear from you all first to make sure I did not miss anything.

Thanks, Jeff

Soundguy · Jul 10, 2012

see if the cyls are bypassing.. assuming you didn't swap any lines around.

FarmerJeff1550 · Jul 10, 2012

That's what I'm thinking now too. I just got back from the hardware store with some 1/4" tube plugs to maybe see if it is one cylinder or the other and I'm getting ready to check the second one the first one had no change so maybe the second one is the culprit.

Still a nice little tractor for the age...

Thanks for the reply

Thanks Jeff...

Soundguy · Jul 10, 2012

remember to leave the drop port on the cyl open and the pressurize the other side run it to lock, and see if oil comes out the drop port.

FarmerJeff1550 · Jul 10, 2012

Well after all my checking I took for granted that the parts store put the new valve together correct. Turns out that when I went to check the centering springs and the reaction plunger I found out they shipped me a valve with four centering springs and no reaction plunger. I put the reaction plunger and ball bearings from the old valve in and it works perfect.

The parts store said they would ship me a new one if I wanted but it works so I said just to double check the valves before they ship. If anyone does get a new valve then make sure you have they right parts in it.

Thanks for your help

I'll be posting more down the road when I tear into restoring my old 4000D HD backhoe circa 1962 or 3 not sure yet.

Thanks Jeff...