Any power steering gurus?

[mtweller]

Ok guys, I am stumped. Since my swap is basically complete, I've been chasing a whining PS pump and can't figure this out. I tried old school "wheels off the ground, lock to lock" bleeding method - multiple times, with as many as 30 reps. I then went "new school" and got a mightyvac and adapter to pull a vacuum on the system. Everything I've read says you should pull about 20in of vacuum and let it sit for several minutes. I can't get more than about 14in and I can hear bubbles, it will drop to 12in and hold. Since I don't have a fluid leak from the box, pump, cooler or any of the hoses, I figure it's sucking air at the box return fitting but there's not enough return pressure to leak fluid - so I replaced that fitting and used loctite 545 for good measure. No change.

However, if I put a hose clamp just past that fitting, I can pull 20in and it holds pretty well (for several mins). If I pull 20in and then release that clamp, it drops quickly to 12in and you can hear tons of bubbles in the reservoir. I'm now of the opinion I must have a leak in the box somewhere on the low pressure side. I'm not sure if there's a seal somewhere that only sees low / return pressure, but if so that would seem to be a culprit here. Any insight?

 

[mtweller]

Crossposted to the 40 forum for more eyes:

Calling Power Steering Gurus, I need some help

Ok guys, I am stumped. Since my LS swap is basically complete, I've been chasing a whining PS pump and can't figure this out. I tried old school "wheels off the ground, lock to lock" bleeding method - multiple times, with as many as 30 reps. I then went "new school" and got a mightyvac and...

forum.ih8mud.com

 

[pvhobo]

I ran into this same problem in the past.
The problem turned out to be the filter/screen inside the pump reservoir was clogged up, not allowing enough flow.
Have you looked at that?

 

[GLTHFJ60]

It's possible your cooler has a leak? Pinhole?

Doesn't make sense that you can't hold vacuum (when the reservoir is capped I assume) but it doesn't leak fluid anywhere.

 

[mtweller]

I ran into this same problem in the past.
The problem turned out to be the filter/screen inside the pump reservoir was clogged up, not allowing enough flow.
Have you looked at that?

That wouldn't explain not being able to pull a vacuum or hold it thought. I do appreciate the input.

 

[mtweller]

It's possible your cooler has a leak? Pinhole?

Doesn't make sense that you can't hold vacuum (when the reservoir is capped I assume) but it doesn't leak fluid anywhere.

Check the diagram - when I put the clamp on and it will hold vacuum, the ps cooler is still in the circuit, so I don't think that would be the culprit.

 

[GLTHFJ60]

OK, so the vacuum test is intended to test only the return side of the system, not the pressure side?

Not sure if a vacuum test is applicable on a steering box design from 50+ years ago. I could try that test on my truck and see if it "passes", and I have no pump whine.

 

[mtweller]

OK, so the vacuum test is intended to test only the return side of the system, not the pressure side?

Not sure if a vacuum test is applicable on a steering box design from 50+ years ago. I could try that test on my truck and see if it "passes", and I have no pump whine.

It should test the whole system, I just assume that anything on the high pressure side would be showing a fluid leak. This really is outside of my scope of knowledge and so I'm really just posting "what I'm thinking". There's a distinct chance that I'm off base, for sure!

 

[GLTHFJ60]

Your assumption is that there is whine, so there must be air in the system. If there's no leaks, and your reservoir fill is the highest point of the system, and you bled it with the tires off the ground, I don't think there's air in there. If you see bubbles in the reservoir while running, I'd wager the pump is cavitating the fluid, either due to a restriction (clogged screen) like the guy in your other thread was saying, or that the pump itself is bad.

Ive had a saginaw pump go bad and whine all the time with no air in the system. In my case it was after I had a line blew once, then again a used pump did the same. In both cases I had to replace the pump to resolve, but the beauty is that they're cheap.

Again, in a pressurized hydraulic system like the power steering system, no leaks anywhere = no air getting in during use, at least in my experience.

 

[mtweller]

Your assumption is that there is whine, so there must be air in the system. If there's no leaks, and your reservoir fill is the highest point of the system, and you bled it with the tires off the ground, I don't think there's air in there. If you see bubbles in the reservoir while running, I'd wager the pump is cavitating the fluid, either due to a restriction (clogged screen) like the guy in your other thread was saying, or that the pump itself is bad.

Ive had a saginaw pump go bad and whine all the time with no air in the system. In my case it was after I had a line blew once, then again a used pump did the same. In both cases I had to replace the pump to resolve, but the beauty is that they're cheap.

Again, in a pressurized hydraulic system like the power steering system, no leaks anywhere = no air getting in during use, at least in my experience.

I could, and probably should, just replace the pump. What baffles me is that the procedure for priming using a vacuum indicates that it should hold vacuum and if it doesn't then air's getting in somewhere. I've had trapped air before and gotten "milkshake" fluid, but that's not the case here. Also, when I clamp the return line and pull 20in, then release the clamp, there is significant audible bubbles in the resi as the pressure drops. Another data point, which baffles me, is that the vacuum holds while the engine is running.

 

[mwalls54]

II would look at a new pump. I have had a few LS pumps do the same over the years. Ive never pressure tested one.

 

[Malleus]

I'm with Johnny on this. I'd try rebuilding the pump; if you buy a new one, you'll get that anyway and you won't get the piece of mind of knowing the rebuld was done properly.

 

[mtweller]

Sometimes the most logical solution is the right one, despite where the troubleshooting takes you

 

[S4Cruiser]

Bling bling!

 

[mwalls54]

your going to be much happier with that.

 

[GLTHFJ60]

So did you get a new pump or just get the remote reservoir setup?

 

[mtweller]

So did you get a new pump or just get the remote reservoir setup?

New P Pump from PSC and remote resi. With the smaller pulley needed for steering linkage clearance, this setup should provide peace of mind for a long time, albeit not cheap.