Power Steering "weak".

[mpyusko]

Ok.... #1, I think hydraboost is the dumbest thing ever. It runs off the P/S so if your P/S dies, or you throw a belt, or you have a low idle, you can't steer and you can't stop. At least with vacuum assist you could still stop.

Anyway... I've owned this truck for over 9 years and it's like when I need power assist the most, it's not there. Low idle, in a parting lot, trying to maneuver and park. Lord help me if the truck is idling and I have my foot on the brake (holding position) and I'm trying to steer the wheels... it's like there's no power steering at all. If the RPM is above 1k, then no issues. My lines were dried out and leaking so I just replaced all the lines and the cooler. I did not replace the pump, the gearbox or the brake booster.

1996 K2500 Suburban, 454

It's always been like this, but I'm going to have to teach my son to drive soon, and he doesn't have the upper body like I do. Thoughts?

 

[stutaeng]

That's true.

The hydroboost is a requirement because it generates higher hydraulic pressure for better braking. Something like 3,000 psi vs 1,000 psi over vacuum-assist IIRC. Hydroboost was used on the trucks with higher GVWR. And all of the other other manufacturers have been doing the same.

Sounds like you have some other underlying problem. Maybe the pump? None of my trucks with hydroboost do what you are describing...

 

[Dropped88]

I had a very similar problem and mine ended up being in the gear box. Mine did all of the above plus randomly if you let off the throttle and start to turn in a curve it would have no power steering so your man handling it 2 handed in a curve and all of a sudden the power steering is back. And now your over corrected in the other direction from all the torque you had on the steering wheel lol

 

[someotherguy]

That's true.

The hydroboost is a requirement because it generates higher hydraulic pressure for better braking. Something like 3,000 psi vs 1,000 psi over vacuum-assist IIRC. Hydroboost was used on the trucks with higher GVWR. And all of the other other manufacturers have been doing the same.

Sounds like you have some other underlying problem. Maybe the pump? None of my trucks with hydroboost do what you are describing...

Pump is the likely suspect. The symptom described is not a feature; it's wear.

Richard

 

[1998_K1500_Sub]

Pump is the likely suspect. The symptom described is not a feature; it's wear.

Anyone have some suggestions on how to test the pump?

It would seem that a high-pressure gauge on a "tee" and an additional hose would be in order, plumbed into the high-pressure side, with appropriate fittings TBD.

Gauge readings should be taken under these conditions:

- low (e.g., how low?) psi with brake off, no steering input
- high (e.g., how high?), steering tight left or right
- other scenarios?

 

[someotherguy]

Anyone have some suggestions on how to test the pump?

It would seem that a high-pressure gauge on a "tee" and an additional hose would be in order, plumbed into the high-pressure side, with appropriate fittings TBD.

Gauge readings should be taken under these conditions:

- low (e.g., how low?) psi with brake off, no steering input
- high (e.g., how high?), steering tight left or right
- other scenarios?

There's probably something in the FSM about it. I'll have to dig in and see, but I'm feeling lazy at the moment. OP could do same with the online manual links and save me from peeling open paper manuals that are buried under a pile of other stuff at the moment.

Richard

 

[1998_K1500_Sub]

OP, you can probably find manuals here:

GMT400 CK Manual Project - The 1947 - Present Chevrolet & GMC Truck Message Board Network

GMT400 CK Manual Project The 1988 - 1998 GMT400 Chevy & GMC Pickups Message Board

67-72chevytrucks.com

and here

88-98 Service Manuals

Over the years I have collected a bunch of GM service literature. Links to PDF Scans of service and STG manuals and a links to the Parts manuals. You'll need the FREE Adobe Acrobat reader to open these files. Get it directly from Adobe here {http://get.adobe.com/reader/} If you're not...

www.gmt400.com

 

[L31MaxExpress]

Pump is the likely suspect. The symptom described is not a feature; it's wear.

Richard

That is actually why I disabled the EVO system on my 97. It was like that from day one. No power steering when you actually needed it. With EVO disabled it steers with 1 finger like older GMs.

 

[1998_K1500_Sub]

FWIW, here's a diagnosis snippet from the 1989 FSM regarding high effort power steering (images below).

I've also attached the 1989 FSM's procedure for testing the PS pump, as a .pdf.

You must be registered for see images attach

You must be registered for see images attach

 

[1998_K1500_Sub]

That is actually why I disabled the EVO system on my 97. It was like that from day one. No power steering when you actually needed it. With EVO disabled it steers with 1 finger like older GMs.

Just to confirm...

Since OP has PS and hydroboost (presumably both OE not retrofit) he would NOT have EVO.

My assumption: EVO is incompatible with hydroboost.