Auto Parts: power steering pump replacement, 1997 GM Suburban 4x4, Power steering pump with EVO

Question
1997 GM Suburban 4 wheel drive power steering pump has a EVO on the pump, can I use a regular pump instead?

Answer
Hi Michael,

To improve the feel of a power steering system at all speeds and to make the system more fuel economical, conventional power steering systems may use electronic variable orifice (EVO) power steering systems. In an EVO power steering system, the fixed orifice of a power steering system is removed in the pump assembly and replaced with an EVO actuator. The EVO actuator is a flow control valve that is threaded onto the outlet of the pump which regulates flow rate as a function of vehicle speed as determined by an algorithm control. The EVO system works by providing high flow rates to the steering gear at low vehicle speeds (EVO actuator fully open) and lower flow rates as vehicle speeds increase (EVO actuator begins to close). A Hand Wheel Speed Sensor is typically used to in conjunction with the EVO system to increase steering assistance when it senses that the vehicle operator is making an evasive maneuver. The excess flow, which the pump produces in high or low speed situations, is normally bypassed internally within the pump.

So to answer your question, NO.  If your vehicle has an evo on the PS pump, then you will need to replace it with the same.  You can not use a regular pump, because regular pumps do not had the flow actuator which works with the vehicle electrical system and alogrithm.

I recommend replacing with a pump with evo.  It will cost more, but you will have the piece of mind knowing that all parts of your power steering system are intact and working properly when and if you will need them.

Please let me know if i can be of further assistance.

Good Luck

Thank You