Help, 964 PS fluid foaming

[yelcab1]

I got no love on the 964 board, so I'll try it here

I am trying to get the 1989 964 PS pump to stop groaning. I have pumped 4 gallons of fluid through the system and the output hose continues to pump out foaming frothing PS fluid. What am I doing wrong?

Resevoir is disconnected entirely.
Input to pump is connected to a hose and dipped into a 2 gal tank of Fresh PS fluid
Return hose is dipped into a 3/4 inch hose and dipped into a collection basket.

picture is of 4 gallons of PS fluid foaming.

[darrin]

not sure if you followed the recommendations contained in my post on your prior thread regarding this matter -- namely:

this might help -- written for a 993, but seems to also apply to a 964
https://www.pelicanparts.com/techarticles/Porsche-993/36-STEERING-Power_Steering_Fluid_Flush_and_Bleed/36-STEERING-Power_Steering_Fluid_Flush_and_Bleed.htm

Specifically "To bleed the system: Refill the reservoir and quickly turn the motor on and off; this will cause the level in the reservoir to drop rapidly so do not let the engine run long as this can introduce air into the system. If possible have a friend watch but do NOT let the reservoir run dry. Once you can start the engine and the level does not drop let the motor idle and turn the steering wheel quickly and at an even pace from lock to lock several times to bleed the air out of the system. Do not force the wheel when turning. Continue this procedure until the level remains constant and there are no more air bubbles in the system. "

[yelcab1]

Originally Posted by darrin

not sure if you followed the recommendations contained in my post on your prior thread regarding this matter -- namely:

this might help -- written for a 993, but seems to also apply to a 964
https://www.pelicanparts.com/techarticles/Porsche-993/36-STEERING-Power_Steering_Fluid_Flush_and_Bleed/36-STEERING-Power_Steering_Fluid_Flush_and_Bleed.htm

Specifically "To bleed the system: Refill the reservoir and quickly turn the motor on and off; this will cause the level in the reservoir to drop rapidly so do not let the engine run long as this can introduce air into the system. If possible have a friend watch but do NOT let the reservoir run dry. Once you can start the engine and the level does not drop let the motor idle and turn the steering wheel quickly and at an even pace from lock to lock several times to bleed the air out of the system. Do not force the wheel when turning. Continue this procedure until the level remains constant and there are no more air bubbles in the system. "

I tried this and it did not work and here is why. The 32 years old pump is shot, air is leaking in and is being pumped through the system making frothing foam. That is never going away by bleeding. I applied vacuum to the system and found it is not holding vacuum which confirms the leak.

So the plan is to replace or rebuild the PS pump and then replace the reservoir. Then, fill and bleed it.

[darrin]

sounds like you've got a GOOD working theory

[yelcab1]

Wrap it up.

The rebuilding of the 964 power steering pump did it. Pulled it, rebuilt it, installed it, fill through with 1 gallon of fluid (once), hooked up new reservoir, turned engine on, it works ... first time.

[yelcab1]

In case anyone is looking for procedures of pulling the PS pump in-situ

1. Remove 4-5-6 header
2. Remove metal cover for the PS belt bracket
3. Remove engine side tin for 4-5-6 side
4. Remove the large bolt holding the pulley to the cam shaft with a stubby air impact wrench (buy one)
5. Remove the four NUTS holding the pump on. Access from the top of the engine (not the bottom), use mirror, go by feel, you have enough room for a 3/8 rachet (3 or 4 degree movements) and long 13mm socket
6. Detach the front bracket to the left - bottom front of the pump
7. Wiggle pump out.

Not fun, but doable if you know the secret steps.

[OSC911]

Awesome, thanks for the tips.