Back in January I replaced my original power steering pump on my 79 F150 because it started making a constant metallic grinding sound. I figured the bearing was going so I replaced it with a rebuilt Cardone brand one. The noise stopped with the new one installed, so problem fixed! Yesterday, the new pump started making the same noise. Almost like someone is holding a screwdriver against the pulley while its spinning. I checked for rubbing and nothing. I did some troubleshooting by removing the belts and the noise stopped with the PS belt removed. What would be causing my pumps to fail? I flushed the system using type F ATF and the fluid is not foamy or low. Could the noise actually be coming from the water pump, but the belt being off is taking lateral tension off that bearing? It's hard to tell exactly where the sound is coming from.

 

Time to get out your straight edge and see if your pulleys are lined up properly. A misaligned pulley on the system can cause all sorts of havoc.

What motor are you running?

 

That's one thing I didn't check was pulley alignment, but it looked close. Its a 351M with PS and AC.

 

My factory P/S pump was not aligned with the rest of the system due to the shims that were used. I had to make some alterations to the water pump side of things to get it aligned. You may need to do the same, but it's going to take a lot of investigation.

 

 

As far as I recall, both A/C and non-A/C systems have a dedicated pulley sheath on the crank for power steering, and there is no idler pulley in either circumstance. However... An idler pulley comes into play when you have A/C installed, but it's for the A/C belt only.

I have two crank pulleys for the 351M/400, one is for A/C and one is for non-A/C trucks.
Non-A/C Crank pulleys have 3 sheaths in total - Smog Pump, Power Steering Pump, Alternator (in that order from the block outwards).
A/C Crank pulleys have 4 sheaths in total - Smog Pump, Power Steering Pump, Alternator, A/C (I'm not sure that this order is correct... but I do know that it has 4 sheaths)

 

Overtightening the drive belt could do it.

 

Did you flush the box before reconnecting the return line back up ? There is more crap trapped in the steering box than you could imagine from years of use plus all the crap that came from the old pump when it went bad. If you didn't ? then all the crap that was trapped in the box went right through your new pump causing the eventual pump failure.

 

 

No, I'm not talking about bleeding the air from it, I'm talking about flushing all the debris out of the steering box that your old pump put out before it died. When your pump was going bad it more than likely put debris out, contaminating the fluid. All that debris was being pumped right into your steering box and that's where it stayed. Then you put a new pump on, you started it up and as soon as it started pumping, it pumped all that debris and the left over contaminated fluid that was left in the steering box and lines right into your new pump causing it to end up going bad. You can't just put a new pump on after something has failed in the system, you have to flush the system out first.

 

I had the same thing with a failed power steering pump in a 1979 F700 many years ago. The mechanic at the dealer ship said to put the pump on the truck and leave the return line (low pressure line) off and let it drain into a bucket. Fill the system with new fluid, start the truck and let the system flush itself into the bucket. Lots of debris came out of that steering box. Turning the wheels from lock to lock at the same time would be a good idea too. Keep adding fluid until it runs clear and then put the return line back on and top up the fluid.

 

If you are still looking for the noise, get a stethoscope. You can find cheap ones at the auto parts stores. Assemble it and put it where you think the noise is. Note: Be very careful as you are placing the tool near moving parts! I have used this tool a few times to locate exact fan squeal and external equipment bearing issues.

 

A much cheaper way to do this is to cut a 4L milk jug in half and get a very long screwdriver. Touch the jug (lid-end, with lid off) to the screwdriver, then touch the screwdriver to the part. It will amplify the sound and you'll be able to diagnose bearings much faster than a stethoscope.

 

 

I have went through a few box store pumps and had issue right out the box. Now I have a tuff stuff Saginaw pump and have not had any issues so far.