1999 Suburban 2500 power brake/steering problems

[capjls]

I have a 1999 K2500 Suburban that intermittently looses power brakes and steering. It has done this for the last three years that I have had it. I have replaced the power steering pump and hydroboost unit, but still having issues. I suspect the power steering pump replacement did not replace the EVO because the mechanic said he got the less expensive unit "without the sensor" (as he put it).

I'm tempted to replace the steering pump again, but I have no confidence this will solve the problem. Could it be the EVO? If it were malfunctioning, could it cause a complete loss of pressure to the brakes and steering? Is there something in the steering box that could be messed up and bypassing all the fluid (causing pressure loss)?

I would appreciate any suggestions for diagnostics or repair. I am completely fed up with this vehicle and I am going to sell it, but I have to fix it first.

Thanks.

[777stickman]

Originally Posted by capjls

I have a 1999 K2500 Suburban that intermittently looses power brakes and steering. It has done this for the last three years that I have had it. I have replaced the power steering pump and hydroboost unit, but still having issues. I suspect the power steering pump replacement did not replace the EVO because the mechanic said he got the less expensive unit "without the sensor" (as he put it).

I'm tempted to replace the steering pump again, but I have no confidence this will solve the problem. Could it be the EVO? If it were malfunctioning, could it cause a complete loss of pressure to the brakes and steering? Is there something in the steering box that could be messed up and bypassing all the fluid (causing pressure loss)?

I would appreciate any suggestions for diagnostics or repair. I am completely fed up with this vehicle and I am going to sell it, but I have to fix it first.

Thanks.

Here's the deal with the hydro-boost brakes. The power steering pump supplies pressure to the brake unit first and then to the steering box and back to the pump. So, yes, I would think that it is a pump issue.

If your mechanic replaced the pump without the EVO (check to see if wires are hooked up at the bottom rear of the pump) then I don't think the EVO system would cause this. If the wires are hooked up down there then yes the EVO could cause this.

Let us know.

[capjls]

So, here is the history on the wires to the EVO:

I was about to replace the hydroboost unit when I discovered that the wire harness that plugs into the back of the power steering pump (I assume this is the EVO connection) had been melted (it was too close to the exhaust manifold). I repaired the wires thinking that this was my problem. But, the problem returned (as I mentioned before, this issue has been very intermittent). I then tried running with the connector unplugged from the power steering pump, but again, the problem returned.

Could the o-rings on the EVO be bad and the fluid just bypassing somehow so no pressure is built up? To me, it is either that or something in the steering gear, but I don't know how to troubleshoot.

My next move is to replace the EVO and pump (if you cannot just replace the EVO).

Thanks for your response.