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So, my steering started acting up last week (in the orv park). I thought it was the pump, and went through a couple pumps at a couple stores trying to "find one that worked." Finally I ruled out the pump and decided its gotta be something in the box. Here's what I know....
The pump seems to have to work really hard, especially when the box is on the left side of center. Power steering works mostly, but it's not smooth, and REALLY slow, even when front tires are lifted off the ground
I took the steering box apart, mostly to clean out the fluid passages.
Put it back in and turned the steering wheel, with the pitman unhooked (no fluid in it and truck not running). It turns pretty easily to the right, but close to center it sorta binds up and it's not smooth or easy to turn to the left and back.
I would venture a guess as a twisted torsion shaft. The way these boxes work is through a torsion bar effect of the input shaft. The more this input shaft twists, the more assist/fluid flow through the spool valve. If your shaft is tweaked, you will end up with good assist one direction, and not so good the other way. I think I'd start with a new shaft and spool valve.
We end up with a lot of these on the Chevy trucks due to cranking on the steering wheel while being towed and not running.
I took the box apart again (didnt fill the fluid since last update). My problem with it being rough turning had to do with not putting the worm gear assembly (?) gear portion straight up and down where it meshes to the sector shaft. I straightened it and put it back together, and it turned smooth as silk with the truck off. PERRRFFECT.....
....Until I turned the truck on and bled the fluid. I left the pitman unhooked while bleeding, just to be sure not to have ANY resistance on it. It turned pretty crappily and slow-like, even without any resisnance. I did it for a few minutes, but it still sounded like it had air in it and all. Finally I hooked the pitman back up and tried to turn it. It turned really slow to the right, really fighting. Then when just left of center, the pump actually STOPPED. The belt was tight enough it killed the engine instantly! I went to pull the pump out and it was way too hot to touch, even the pulley. I can turn the pump, but it sounds really nasty like rocks inside.
How can a box be frying pumps? That's my only guess
Let me know what you figure out! Ours was "catching" just off center to the left and then the box started leaking. Tomorrow I am changing out the pump and the steering box. I don't want to junk the old box if its an easy fix. They are hard to find for a 78 Bronco.
Oh yeah... the reason I'm changing out the pump also is this:
Someone said to try Lucas steering sealer and after putting in the Lucas, the pump started whining and the box had power to the right and was hard as hell to the left. I'm guessing that the Lucas additive did something to aggravate the problem. It sure didn't stop the box from leaking!
I would try it hooked up to the steering linkage without the engine running, just to make sure something isn't binding in the linkage. Are there bubbles in the reservoir ? You'll need to put a psi gage in the high psi line to see if the pump is any good.
I have this same problem with my 78 power steering (f-150). Turns fine one way and hard the other. Also there are alot of bubbles in the reservoir like mark said, so much that it will cause the fluid to overflow after running for just a short time. I have at LEAST one leak...not even sure where but I believe at the steering shaft input but possibly at the line connections and sector shaft?? Could the pump be pulling air from the leaks. any ideas???
Bubbles can only mean it's got or getting air in it. A input or pitman shaft seal probably wouldn't be the cause, usually its a bad hose, bad pump. You can smoke a pump quick if you got air in the system.
Yeah I think the pump is shot...i havent driven it for probably 6 months and just havent had the enthusiasm to go fix on that pickup. Funny you say that ivan...the pickup in question is the one i am going to cut up and make a mudracer.