My girlfriend and I just bought a '79 FOrd F-150 4x4 (351M/auto) from auction at at a steal of a price. . .the engine runs great, trans works great, drives great, 4WD works just fine basically no major problems and nothing missing.

My only problem is with the power steering. . .it constantly is moaning and groaning when I turn and it's very inconsisten as to the amount of effort I have to exert to get the wheels to turn. I know it's an older vehicle and I can't expect PS like a new vehicle necessarily, but I would like it to be consistent. . .it takes more effort to turn one direction than the other and it's always easier to turn while backing up than going forward (that kinda makes sense though. . .I think???). It's hard to turn when sitting still (also kinda expected since it's older, larger tires (not huge though. . 33's). It was missing the power steering pump reservoir cap, but I have replaced that (it had a rubber stopper that was zip-tied on to hold it in place, but it kept blowing off after the truck was shut off!!!), refilled the reservoir with fluid to the correct level and checked the level repeatedly it it's always the same.

Any ideas of what to do to fix the problem before I replace the entire PS system and waste a lot of time and money?

Thanks!

 

I heard that the "moan" you speak of is due to dirt and debri from pump wear in the PS fluid and I was also told to add a fluid filter to the inlet side of the pump to remove the particles. So you could try to flush and change your PS fluid and add an in-line filter at the same time to see if it will fix your PS issues. From your description though, I think you should bite the bullit and replace your pump, because the noise is part of the problem. I rebuilt my PS pump and added a Magnafine AT filter to my PS system as part of my frame-off restoration of my 77 F150, but I can't tell you how well the setup works yet, since I have not started the engine yet. I just posted pictures of this recently in this thread:

https://www.ford-trucks.com/forums/7...n-ps-pump.html

 

The sound you hear can be from fatigued fluid, and that noise is cavitation. Cavitation is from foaming. Changing the fluid always helps, and coolers and filters also add life to any pump system, as there is a bunch of heat generated by the pump.
You probably need a new pump, and you might look into installing the upgrade saginaw pump found in later ford vehicles. Much better pump.

 

Cool. . .thanks for the tips and suggestions guys. . .I'm gonna go ahead and upgrade to the Saginaw pump. . .it was something on my do eventually list anyway. . .I will also add the cooler and the filter because I know that the fluid was heating up because the pressure was blowing the rubber stopper (makeshift reservoir cap from previous owner)off all the time!!! So a cooler probably isn't a bad idea either.

I would say that my fluid definitely needs replaced because it has been foamy every time that I checked it. . .forgot about that until you mentioned it 75F350!!!

I will go ahead and add the filter as well since it sounds like I'm gonna be replacing the hoses and pump might as well do it right from the start rather than try to piece meal over time.

What do you guys think about the steering box. . .that should be fine right???

Thanks again!!!

 

Cujo8. . .thanks for the link to the other thread. . .

That's a nice looking engine by the way. . .hope mine looks that good soon!!!

 

I gotta say, if it's easier one way than the other, it sounds like the springs in the spool valve in the steering box are weak or the valve is leaking internally. Probably one or two springs are broken.

If it were me, I'd just replace both the box and the pump - and the hoses just to be sure there's no dirt in them.

If you want to try cheap first, change the fluid and put a filter on it. And drive it for a while.

Chances are, if the cap was gone and the fluid disappeared, they put the wrong fluid in.

Which might be the reason for all the moaning in the first place

 

You most probably have an air leak effecting the suction side of the pump.
The oil foaming is outside air being drawn into the system. (Pseudo-Cavitation)
If you don't repair the air leak, before you put a new pump on, you will tear up the next pump also. Check your hoses for oil weeping, lose clamps, bad o-ring, a loose fitting, cracks or breaks.
When I brought my truck it had a noisy pump and I found the high pressure was leaking at the crimp and a low pressure hose had a hose clamp loose. I kept hunting for leaks until the fluid stopped foaming.
When the pump compresses the air bubbles, the temperature of the compressed air, gets high enough to damage the metal in the pump and harm the oil.
If you install a new pump, try to prime the pump by filling the reservoir and turning the pulley by hand until it starts to push oil. There are some studies that show a dry started pump has half the life of a primed pump.

 

I would definitely replace the hoses if I replace the pump. . .

The funny thing was that the fluid level never lowered even with the cap missing from the PS pump. . .I'm SURE there is dirt in there. . .

That's the thing about getting somebody else's stuff. . .you always have to fix something!!!

 

I just replaced my pump for this exact same problem and the pump was $38.00 from Autozone rebuilt. It works great and was a breeze to install. Just remember to use the proper tool to remove and install the pulley back onto the new pump. It will make life so much easier.

 

Here some info on the Saginaw pump from PJB...

Saginaw power Steering pump 20-6244