Troubleshooting Power Steering

[Matt in TN]

I just bought a 1973 Ford 4000 and the power steering (hydro assist, it looks like) doesn't work. You can turn the wheels while moving, but not at all while sitting still. The prior owner said he's been running it that way for years, and only recently found out it was "supposed" to have power steering.

In my fluid/filter changing "just bought a new/used tractor" routine I filled the PS pump/resevoir, which was definitely low. I did not check to see if it was completely dry, but I would assume so from the PO's stories. I'm thinking the pump is bad, but I'd like to verify this before I blow $300 on a new pump. What sort of pressures should I be seeing out of the pump? Is there a checklist I can work through to troubleshoot the entire system and verify it's the pump (or find what else might be wrong)?

Lastly - does anyone have any recommendations on where to get a new pump or other parts, other than the dealer?

Thanks -

Matt

 

[FULLPULL]

If it worked good after adding fluid you might only have to replace the seals in the pump. My guess would be the pump is worn along with the seals .You may be able to get a rebuild kit and you will need the bushings inside of the pump.

 

[Matt in TN]

No - adding fluid made no difference to the operation. I'll see about a rebuild kit - I didn't think about that option.

 

[Wayne County Hose]

If the 4000 is anything like the 3000, I have quite a bit of experience with this. Unfortunately, all BAD experiences.

 

[Matt in TN]

I would guess they're very similar - share your experience, Hoseman!

 

[Soundguy]

I believe once the housings wear, repair is by replacement.

Probable a lost cause at this point.. but has the ps filter been changed?

if it ran without oil for an extended amount of time.... you might as well go fishing with it and use it to keep your boat stationary by tying a rope to it..

soundguy

 

[RickB]

I can't give you a pressure spec without knowing if it is a general purpose 4000 or an SU model. Also, late general purpose models have a higher pressure spec than early, so give me the year. Pressure test by installing a gauge in the pump output and deadheading the pump for a short period of time. Then tee the gauge in the pressure line and hold the wheel at full lock briefly. This will compare the condition of the pump/ relief valve to that of the steering valve. Your dealer may have access to aftermarket pumps supplied by A&I or other aftermarket sources that will be substantially less costly than OEM. The only parts available for these pumps is a seal kit which is a waste of money unless you have a pump that builds good pressure but leaks externally.

 

[Matt in TN]

It's a 1973 model. I have not yet changed the PS filter. I think you're right soundguy, but I may pull the pump and tear into it just to see what it looks like before I get a new one on the way. The dealer recommended aftermarket as well, and quoted me $300-350 for a pump ($700-800 for a New Holland pump).

I'd be curious to tee in some gauges and know for sure what's going on, but it may be a waste of my time at this point. Would a 0-1000psi gauge give me enough headroom, or could the pressures go higher than that?

Edit - not sure if it's general purpose or SU (what's SU - "Sport Utility"? ) How would I tell?

 

[Soundguy]

SU.. ome call it special utility.. some super utility.

SU would be a machine that had the light duty swept back front axle of a ford 3000.. IE.. radius rods and such.

I like a 0-3000 psi gauge for hyd applications on ag tractfors.. but you generally can get by for less on the PS systems..

soundguy

 

[FULLPULL]

The last power steering pump that i priced was around 7 or 800 bucks . If it was 3 or 350 i would have gone new . When you take the pump off of the tractor see if the bushings are worn by rocking not turning the gear it will have play in it at least the last one i worked on did. There should be a parts break down on the NH web site under your model of tractor.

 

[RickB]

It's a 1973 model. I have not yet changed the PS filter. I think you're right soundguy, but I may pull the pump and tear into it just to see what it looks like before I get a new one on the way. The dealer recommended aftermarket as well, and quoted me $300-350 for a pump ($700-800 for a New Holland pump).

I'd be curious to tee in some gauges and know for sure what's going on, but it may be a waste of my time at this point. Would a 0-1000psi gauge give me enough headroom, or could the pressures go higher than that?

Edit - not sure if it's general purpose or SU (what's SU - "Sport Utility"? ) How would I tell?

The pump for a 73 4000 general purpose has a relief valve set at 1100psi. A 73 4000SU (special utility) has the relief set at 650. If you replace the pump, be sure you purchase the correct one. Replacing a worn out 1100 psi pump with a fresh 650 psi pump won't help much. Going the other way may well cause leakage in the 35 year old steering valve/column. The 4000SU steering box has two pitman arms and drag links, the 4000 general purpose has one pitman arm and drag link.
You should invest in a filter change before investing in a new pump.

 

[Matt in TN]

Just a follow-up for anyone else searching this out -

I replaced the power steering pump filter and found the old filter had come apart inside the pump and the inside hole was greatly elongated. I also put a 0-1000psig gauge teed into the output just downstream of the pump. I filled it with fluid and fired it up, and was suprised to see the gauge register pressure! After cranking it back and forth several times to bleed the air out of the system and topping off the fluid (with the loader holding the front wheels off the ground), the pump developed 650 psig at lock just like it's supposed to (it is the SU model)

I did notice one of the seals on the cylinders is leaking, which explains the lack of fluid in the system. I'll be taking that to a local shop for a rebuild, and then hopefully I'll be good to go. I took it out around the yard with the leaky cylinder just to feel what it was like and the difference was amazing!

Thanks to everyone for all of the help!

 

[Soundguy]

Glad it was mostly a filter fix for ya... never hurts to try the cheap stuff.

now you just need to tackle that cyl..

soundugy

 

[japody]

I have a similar issue with my 4000's steering. I'm fairly new to the world of tractors. Can someone clue me in as to where the power steering pump filter is located?

Japody

 

[Soundguy]

so.. which 4000 do you have? a 4000 4 cyl.. or 3 cyl.

if a 4 cyl.. look at the upper right of the front of the engine.. should be a resevoir with filter in it.

if a 3 cyl. find your pump.. ( left front ).. again. filter in resevoir. but is a different setup than older models.

 

[japody]

It's the 3 cyl. Thanks!