LB7: No Power Steering

[nitrous]

About a year and a half ago I swapped out my factory PS pump because it was groaning and installed a Lares remanufactured one from Rock Auto. It was go for a little over a year until I started loosing power steering/brake pedal feel intermittently. Just installed a “new” Lares PS pump under warranty as well as the return line from the steering gear to the PS pump and the pressure line from the PS pump to the hydroboost. Also replaced all the fluid, which was from Menards and I found odd that it was red. Anyone ever seen red universal power steering fluid before? Anyways, I got everything installed and flushed, bled the steering by going lock to lock about 15 times twice. Everything feels good with the wheels off the ground, but once the truck is on the ground I still have no PS.

Could it be another faulty pump? Could the fluid be wrongly bottled (ATF)? Do the hydroboosts fail? Frustrating to say the least.

Thanks for any help.

[nitrous]

I should also note that I added a cooler to the system while I changed out the pump. There are no leaks.

[heymccall]

Oil is oil for this application.
Sounds as if the flow control valve is stuck.
On a Saginaw pump, the flow control valve holds the reservoir on, and, the pressure out line threads into it.
Did the pump come with the valve?

[nitrous]

I would assume the pump came with the control valve pre-installed as it was a complete unit like you would buy at an auto parts store. The only parts I swapped over were the mounting brackets and reservoir cap. The reservoir was pre-installed with the new pump.

I did install a new pressure line from the pump to the hydroboost. There’s no leaks and it’s tight. I do notice a slight groan from the pump with the wheels turned when trying to move the truck. It also looks like fluid is coming out slightly from the cap. Possibly a bad reservoir cap but seeing as the lines are under fluid it shouldn’t be letting air in the system. Maybe a blocked return line? I may try replace the hydroboost to pump return hose tonight.

[nitrous]

I replaced the return hose from the hydroboost to the pump, no change. The only line I have replaced is the gear to hydroboost line, but it was replaced less than 2 years ago.

I called Lares and talked to them. They said the check valve behind the pressure hose fitting on the pump may be stuck. So I took out the pump, pulled the line and fitting and ensured the valve moved freely. Reassembled everything and still the same situation. Butter smooth with the vehicle raised, but as soon as I lower the tires it’s impossible to move the wheels without moving the truck some.

Are the hydroboosts common to fail?

[nitrous]

Just to update and in case someone comes across the thread in the future.

I called and talked to Lares and they suggested first that the check valve was stuck as it got air behind it. So I pulled everything out and took off the pressure line fitting and the valve moved freely. Put it all back together and same thing. I told them this and they insisted that I must be getting air into my system somewhere in either the brakes or the steering. Even after I told them that every single component in both systems was new aside from the ABS module.

I bought the newer AC Delco PS pump I read about. Apparently it has 12 vanes as opposed to 10 on the older models for 01-05 years (they are interchangeable). Part number 20756713. Installed it today, did a simple 15 lock to lock turns of the wheel with the wheels raise and raise the system. Put it down and it works like new.

I’m the end just buy a new GM part and Hopefully it saves peoples the headache I’ve had for the last five days.

[csibbs]

I'm sort of in the same boat as you. After defecting out two steering boxes, and 4 power steering pumps, this problem persists. I'm leaning towards the pressure relief valve constantly getting stuck as well. This has been a frustrating 3 week endeavor for me

[davester]

could it be just not getting completely bled? I know the full-service manual says to use a special cap on the PS pump and then pull a vacuum on the system to do it, vs just turning the wheel left and right & pumping the brakes.