Power Steering issue

[Lifted98]

I have a 1998 k1500 Silverado 350 engine with 4" lift, 33" tires, Dual steering stabilizers that i just had the power steering pump go out on me. I replaced it then the steering gear box crapped out a week later. It had the EVO steering setup on it and it had been twitchy for a while in slow speed cornering. I saw the kits GM put out to delete to EVO assist but read I could just use the hose off a 96 model. So I got the hose and a box off a 96. I used to have a lot of play in the steering, but now steering is tight and it goes straight down the road without much effort. My issue is not so much the highway driving , its the slow in town stuff. I'm pretty much having to use two hands while making turns. There is assist, but not much. I have no air in the system. Only thing I can think is I checked Power steering part numbers for the 98 and the 96 and they are different. Would this be the culprit? I'd hate to have to change the pump out since it's new. Any help would be greatly appreciated.

 

[chipskittles]

The rebuilt pumps are notoriously crap. I went through 3 a few years ago before I got a solid one. The part number is probably not the issue, it's just a junky pump more likely. People say you have to bleed the power steering after changing the pump in a very specific way, with the wheels off the ground, and never let the reservoir run dry. I agree with these people, it could not hurt.

 

[Lifted98]

The first pump I put on was a dud. It didn't last a couple days. The second one I bled just like you were saying. No air in it. I've seen tutorials where they drill out the orifice that threads into the back of the pump. I have and extra from a salvage yard pump. I thought about trying it. It's supposed to help with low speed pressure.

 

[chipskittles]

I think there are different size pulleys as well. That will change things for you. I know for a fact that the various part numbers of saginaw steering gears have different spec torsion rods and different size orifices in the valves. It gets very complicated very quickly

 

[Ken K]

If I remember correctly, the "EVO" or electronic variable orifice system reduces P/S pressure at highway speeds to increase fuel economy, but increases at slow speed. Now, what controls it? The "Hand-wheel-speed" sensor at the bottom the steering column provides information with two signals, 5 volts each...one goes high while the other one goes low, this signal indicates turning rate. The BCM may control the flow rate of the pump by turning on the circuit or shutting it off. I no longer have access to GM eSI to get schematics, but removing the valve at the pump, replacing the pump or supplying the "EVO" with 12 volts constant with key, is one of several ways to get around it.

 

[Lifted98]

I tried unplugging the valve before I changed the last pump and removed it altogether. It was scary. I plugged it back in the same day. I'm probably going to try and drill out the hose fitting on the back of the pump a little. If I don't like that I might put the EVO valve back in and see if it is any better. I'm just trying to get the slow speed steering better.