Power steering question..

[97K1500Silverado]

If you have EVO (which it sounds like you do), it's known for failing with age.

IIRC the usual problem is the sensor, which senses steering wheel rotation, fails.

The usual "fix" is to remove the EVO (electronically variable orifice) from the pump and replace it with a fixed orifice. Kits for doing this were once sold by GM but have been discontinued. Dorman has a kit, or you can "do it yourself" by ordering the relevant parts.

I guess I could disconnect the connector at the pump. What should that do? Hopefully increase power assist?

 

[1998_K1500_Sub]

I guess I could disconnect the connector at the pump. What should that do? Hopefully increase power assist?

When I did that to mine (1998 Suburban), it remained at "high assist" (light steering) all the time. YMMV, depending on what's actually failed.

 

[97K1500Silverado]

When I did that to mine (1998 Suburban), it remained at "high assist" (light steering) all the time. YMMV, depending on what's actually failed.

Disconnected and no change. Steering still really heavy. Does that mean I need a new EVO valve? Or just go for the bypass kit? Thinking my pump is ok since they either work or completely fail with no assist in my experience. No odd noises from my OEM pump with 210k miles.

 

[1998_K1500_Sub]

Disconnected and no change. Steering still really heavy. Does that mean I need a new EVO valve? Or just go for the bypass kit? Thinking my pump is ok since they either work or completely fail with no assist in my experience. No odd noises from my OEM pump with 210k miles.

I would guess the pump is OK and the EVO is at fault, based on the likelihood of failure (pump is relatively simple, EVO is relatively complex).

The course of action is up to you.

EVO is a problem waiting to happen IMHO and can act-up in ways that are disconcerting, e.g., see this thread:

Unpredictable Steering

Hey All, I have a 97 C1500, I am getting a very unstable steering wheel and sometime when i hit a some bump in the road it becomes very unstable and unpredictable, it seems like im all over the road. i have put leveling blocks on the front springs. it was like this before the leveling blocks...

www.gmt400.com

The guy above disabled his EVO and problem solved.

If you want to know a bit about the EVO device itself, see this:

Delphi Electronic Variable Orifice (EVO) - Slicksheet

I was rummaging through some old computer files and I found this Delphi Electronic Variable Orifice ("EVO") 2-page slicksheet with copyright date 2005. I thought someone here may find it interesting, since many GMT400s were equipped with EVO. (edit) I also found an interesting explanation of...

www.gmt400.com

 

[97K1500Silverado]

Appreciate the quick replies and detailed info!

There’s some videos of my 97 along with other vehicles in the family on my YouTube channel.

DocTube

Share your videos with friends, family, and the world

youtube.com

 

[1998_K1500_Sub]

There’s some videos of my 97 along with other vehicles in the family on my YouTube channel.

DocTube

Share your videos with friends, family, and the world

youtube.com

Nice looking K1500

 

[97K1500Silverado]

Driving around today I have full boost all the time with connector unhooked from PS pump. I searched eBay for Dorman variable steering bypass kit 926-049 $20 shipped

 

[1998_K1500_Sub]

I searched eBay for Dorman variable steering bypass kit 926-049 $20 shipped

It’s been said it can be installed w/o pulling the pump.

I pulled the pump.

YMMV.