Non-Hydroboost Power Steering and Brakes Linked?

[510man]

Yes, same problem with both pumps. I assumed the rebuilt pump was failing so bought new vs rebuilt the second time. No notable change.

I found the GM valve I bought. Part# 7809221. Unfortunately, it's rusty so I can't use it for testing.

 

[510man]

No pressure switch, BTW.

 

[exp500]

Rereading this whole thing- filter restricted most likely. Especially since system went years working without EVO.
If that doesn't work, use the relief valve assy complete including spring from the 96 pump that worked previously.
If that doesn't work it pretty much has to be pump. Flush uses about 2 quarts. Buy a new Oring.

To clarify- The EVO valve part with wires is gone, The original(99) relief valve is the one you are using.

 

[510man]

Rereading this whole thing- filter restricted most likely. Especially since system went years working without EVO.
If that doesn't work, use the relief valve assy complete including spring from the 96 pump that worked previously.
If that doesn't work it pretty much has to be pump. Flush uses about 2 quarts. Buy a new Oring.

To clarify- The EVO valve part with wires is gone, The original(99) relief valve is the one you are using.

The original 99 would be the EVO valve. I'm not using it. It resulted in full assist all the time when unplugged. Both the rebuilt and new pumps came with a new valve installed. I assumed it to be a 96 style valve since I ordered the pumps for a 96 truck. They didn't result in full assist like the original valve did so I assumed they were correct.

I thought about the filter too. I would think the problem would increase with RPMs if the filter is clogged. It would be pretty easy to remove and test with a bypass though so I should do it to confirm it is or isn't the problem.

Still puzzled how the brakes have anything to do with it at all.

 

[exp500]

Brakes mean low RPM, and hi load on steering. Try the filter. If that doesn't work, Switch to the 96 relief. If that doesn't work Warranty swap Pump. You covered most everything else.
Would not be the first time bad parts made a guy loose some hair. Our local AZ recycles returns alot at the distribution center level,so much that my friend paint marks his shops returns with 3 dots so he doesn't waste labor anymore.

 

[east302]

Relating to the timing of this issue, when was the filter installed? A restriction there would cause a pressure drop that may not be overcome at idle with lower engine speed. Quick test is to remove the filter and see if it improves things. The stock pump would not have been sized for it but may have had enough margin to overcome the additional drop with a clean filter. A dirty filter combined with lower pump speed would make it worse.

Do you have a scanner to read the engine speed and see what it is when brakes are applied? What is commanded versus actual rpm. Or, what’s the tach say?

Spec is 550 +/- 25 rpm at idle in drive, warmed up in closed loop.

I’d agree with exp500; engine speed is the only correlation that I can think of as there are no electronics on your power steering.

Edit:

You said it “Happens at idle. I can shift to neutral or park, rev the engine to 2k, and no change until I release the brake pedal.”

So if you’re sitting still with brakes applied in park at idle, is there a difference in steering effort versus turning the wheel in park at idle without brakes applied?

 

[510man]

Edit:

You said it “Happens at idle. I can shift to neutral or park, rev the engine to 2k, and no change until I release the brake pedal.”

So if you’re sitting still with brakes applied in park at idle, is there a difference in steering effort versus turning the wheel in park at idle without brakes applied?

Sorry if this part was unclear. Your question is the core of my problem. Steering at idle with brakes applied is normal for maybe a half turn of the steering wheel and then it's as if there is no PS........until I release the brake. Then it's normal. Steering at idle without the brakes applied is normal all the time. Power assist works turning the steering end to end without issue. Hence, why I'm puzzled how the brakes have any impact when I'm working with two independent closed systems.

The filter was installed with the new pump per the warranty. No filter = warranty voided. There was no filter with the OEM EVO pump nor the Delco rebuilt pump. I agree removing the filter is the first thing to try. I'm thinking this pump may be low pressure. I'd test the pressure but I haven't found a place to rent a PS pressure tester. The tach shows 600rpm at idle in gear. That's not an accurate reading. I'll have to look to see if my OBDII tester has a tach. I've never used it with the engine running. I've only used it to pull and clear codes.

I guess there could be an obstruction in the steering box itself, which we haven't contemplated in this thread. I don't know how I'd test that. Let's see what the filter test shows. I'll do that Saturday if I can find a barbed tube to put in place of the filter. I had to cut the new line to install the filter.

Thanks for all the help thus far.

 

[exp500]

Just Buy a hose. Quit adding restrictions in an already undersized return line.
They sold you a $2.00 filter for $29.99 for warranty! And you expect it to work?
We haven't even addressed the possibility of Wrong P/S fluid. Repackaged Hydraulic fluid (usually under $15 Gallon for good stuff, with most rebuilders recommending ATF). If Filter, it is foaming.
If you want to keep overthinking this rather than actually testing it, we can do it too!

 

[510man]

Go back and re-read. I said I'll test it Saturday. I'm quite remote at the moment so I'm ordering in parts, which takes days. I appreciate your input but you're welcome to move on if waiting a day or so is too stressful for you. We'll all be just fine either way.

 

[exp500]

I guess my post wasn't as humorous as I thought..... Nice reply,,,,, I'll watch now!