1960, 730 Diesel, Power Steering Pressure

bwlyon

New User
Ok, just had Power Steering pump and pedestal overhauled due to no power steering at my local JD Dealer. It is all back together now, and the first problem was leaks so I tightened all the lines and bolts up, and now it's dry. Second problem was no power to the left, which I fixed by centering control valve assembly. Now I have power steering both directions; however, the assist is non existent at slow idle. If I throttle it up to fast idle there is a fair amount of power assist, which I could live with, but I would like it to steer easy at slow idle. This leads me to what I've done to try and rectify the issue. 1. I have tried adjusting the flow control screw to no avail. 2. I have tried to shim the relief valve to increase pressure. I have .180" of shim in now and has done nothing to increase pressure from the original .120" of shim. My best lock to lock pressure is like 1000-1100 PSI and you have to wait for the pressure to build that high. I am sitting at around 500 PSI when I turn the steering wheel left and right. I have a new relief valve spring ordered and will try to add pressure latter in the week, but I'm not convinced this will help. Any Ideas or suggestions is much appreciated. Also, how easy should the steering wheel turn at idle? If memory serves me right, the old 730 we had on the farm back in the day turned really easy.
 
Reading your post, it seems to me things could be WORSE!

If, in fact, a dealership did the "OH" and got it done for less than the tractor may be worth, that's a PLUS!

Beyond that, as was discussed here some days back, the center section of the pump and the gears wear over time, and a simple "overhaul" which translates into a "reseal job" ain't gonna fix those evils,.

IMHO, you need to live with weak PS at idle or throw BIG $$$ at the pump.
 
(quoted from post at 19:48:36 06/30/14) Reading your post, it seems to me things could be WORSE!

If, in fact, a dealership did the "OH" and got it done for less than the tractor may be worth, that's a PLUS!

Beyond that, as was discussed here some days back, the center section of the pump and the gears wear over time, and a simple "overhaul" which translates into a "reseal job" ain't gonna fix those evils,.

IMHO, you need to live with weak PS at idle or throw BIG $$$ at the pump.

BIG DOLLARS is right! Priced center body for the pump and price is $300+. YIKES!!!
 
I picked up an extra flow control valve ( I think that's what they call it )and experimented with it. On some it did help to bore the center orifice bigger. I used an 1/8" carbide tipped masonry bit IIRC. and bored it in the lathe.
I used an extra one because once you bore it out you can't go back in case it doesn't help or gets worse.

Did they put new vanes in the cylinder ? and o-rings on the main steering shaft ? As in reseal the COMPLETE unit.
 
I can remember our 630 having weak steering at low engine speeds with it warmed up back when the tractor was only a few years old. Today the same tractor is the same way with an estimated 15000 hours. The vanes and pump seals have been replaced but the pump internals are still original. It steers fine at cold idle but needs to be revved above idle to have power steering when hot. It never has steered fast like the new gens. It went down into a steep road ditch once because the steering locked. VERY scary experience.
 
(quoted from post at 21:59:17 06/30/14)
BIG DOLLARS is right! Priced center body for the pump and price is $300+. YIKES!!!

That's not too bad. Consider how many were made and how few parts are still available. I'd pull the pump, check it out and throw that puppy in there if needed. And be happy Deere still has a section available.

Adrian
 
(quoted from post at 05:19:56 07/01/14) I picked up an extra flow control valve ( I think that's what they call it )and experimented with it. On some it did help to bore the center orifice bigger. I used an 1/8" carbide tipped masonry bit IIRC. and bored it in the lathe.
I used an extra one because once you bore it out you can't go back in case it doesn't help or gets worse.

Did they put new vanes in the cylinder ? and o-rings on the main steering shaft ? As in reseal the COMPLETE unit.

Yes, the whole front end was out of tractor and resealed including the vanes. I will keep tinkering with it till I get it as close to right as possible. I kind of wish I would have torn the pump apart myself, at least I would have seen with my own eyes if the pump body and gears were in decent shape. I have my fingers crossed it is only a weak pressure relief spring causing the issue.
 
Ok, I replaced the pressure relief spring to no avail, pressure remains the same. I adjusted the assembly to give equal steering effort right to left, which gives a slight amount of drift to the left. I can live with that for now, but I can see a new pump body, and another disassembly of the upper part of steering mechanism in the future to get it "Right". Hopefully, within the next couple of years I can afford to do a complete restoration front to back.
 

The flow control valve's function is to prevent too much flow.
The relief valve's function is to limit max pressure.
Neither function until the pump moves enough oil and moves that oil against a restriction.
There is either internal leaks, thin oil, leaking valves or a worn pump . Were the pump end plate milled smooth and flat? What was the gear to end plate clearance ? Sometimes the middle body needs a few thou milled narrower.
 

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