Power Steering/Hydroboost Problem

[tloomis]

I hope some one can help me out with my problem. As you can see in my signature I have 1997, C2500. I lost power steering and Hydro Boost so in trouble shooting I disconnected the pressure line from the pump to the Hydro boost and there was no flow. I replaced the pump and still no flow. So I started researching the funny looking contraption hooked to the pressure port of the pump and found that it is called an EVO electronic variable orfice. Basically it takes a signal from VSS and controls the pressure out of the pump. Should have full pressure at idle and as your speed increases orfice closes to reduce the pressure/flow to the power steering, an early version of speed sensitive steering. Well this is what has gone bad on mine. I went to the local parts stores NAPA, Auto Zone and Car Quest and they couldn't get one, so I went to the dealer and he tells me the the part has been discontinued with out replacement so I ask the Mechanic why GM would do this. He said probly because they had a very high failure rate. The part guy did find a couple cubby holed at two dealers close by, so I called them and was quoted a price of $135.00. I ain't payin that much.

Here is what I want to do. I want to convert back to the mechanical pressure relef valve pressure port hook up but, to do that I need to get the right pressure hose. In my research it seems GM only used the EVO system on the 1997 & 1998 trucks, so I went to NAPA and ordered the hose for a 1996 truck and it has all the right bends but, the end for the pressure port on the pump is too big. Can any one help me on this.

[More Power]

Either an adapter (if it can be obtained or made - don't know if something like this is available) or a 1996 PS pump..... :(

In the FYI category - It's interesting to note that a 1989 PS pressure hose, made for a 6.2L diesel application, fits a Duramax PS pump perfectly.....

Jim

[CareyWeber]

I hope some one can help me out with my problem. As you can see in my signature I have 1997, C2500. I lost power steering and Hydro Boost so in trouble shooting I disconnected the pressure line from the pump to the Hydro boost and there was no flow. I replaced the pump and still no flow. So I started researching the funny looking contraption hooked to the pressure port of the pump and found that it is called an EVO electronic variable orfice. Basically it takes a signal from VSS and controls the pressure out of the pump. Should have full pressure at idle and as your speed increases orfice closes to reduce the pressure/flow to the power steering, an early version of speed sensitive steering. Well this is what has gone bad on mine. I went to the local parts stores NAPA, Auto Zone and Car Quest and they couldn't get one, so I went to the dealer and he tells me the the part has been discontinued with out replacement so I ask the Mechanic why GM would do this. He said probly because they had a very high failure rate. The part guy did find a couple cubby holed at two dealers close by, so I called them and was quoted a price of $135.00. I ain't payin that much.

Here is what I want to do. I want to convert back to the mechanical pressure relef valve pressure port hook up but, to do that I need to get the right pressure hose. In my research it seems GM only used the EVO system on the 1997 & 1998 trucks, so I went to NAPA and ordered the hose for a 1996 truck and it has all the right bends but, the end for the pressure port on the pump is too big. Can any one help me on this.

Do you have the part # of the EVO that is $135.00?

Carey

[Scooby]

I have had hoses "adapted" by a good hydraulic shop before. They can usually re-use the fitting from your old hose and crimp it to the new hose- IF the hoses are the same ID. ALSO- they can cut off the end of the new fitting, and weld the end of the old fitting on in its place. Again, this is done by a GOOD hydraulic shop, and depends on what type of fittings are on the hose. You could also have them cut the hose and splice the end of the hose you need onto your old hose.

Just some IDEAS.

[Bnave95]

Any chance the vssb went bad? At the time was there any speedomer readings? Just a thought.

[tommac95]

i think the PS pump output comes thru a 'screwmachined part' that bolts to pump body thru cannister....so could you get a boneyard pump and just swap over that item [nut/bolt/valve-body] If still need adapter, as mentioned above, good autoparts/machine shop or hydraulic shop should work.