Monday, June 24, 2013

Control valve reseal

Next up in the Power Steering resealing project is the control valve. The control valve hangs below the steering box on the pitman arm, with the reach rod to the bell crank extending out of the front (in the pictures below this part had already been removed). The motion of the pitman arm pushes the reach rod forward or backward to turn the front wheels; the control valve captures this movement through a sliding ball stud which moves a slotted piston (called a valve spool) back and forth. As it slides past openings within the housing, it allows power steering pressure to activate a piston in the power cylinder mounted between the frame and the bellcrank. This provides power assistance to the steering.

Don't worry, there won't be a test.

Now back to the reseal. This is the easiest one as the kit only contains two o-rings. It can even be done with the control valve mounted on the car.

First, into the tray for cleaning!

It wasn't terribly dirty since I'd already lightly cleaned it previously.
And now disassembly. First, the two screws holding the cap are removed.

Next up, that nut holding the spring under pressure comes off, and the piston assembly slides out.

Confession time--in the picture above, since the unit was off the car, I removed the two bolts holding the housing and the ball stud sleeve (on the far right) to make it easier to reach the second o-ring. Plus it allowed me to thoroughly clean the housing.

Assembly was, of course, the reverse of the above process, after coating the moving parts liberally in power steering fluid.

On the far right is a plastic cap, only fitted on the 64 models, to help keep debris out of the grease in the ball stud sleeve. This appeared to be slightly distorted (grease was leaking around it) so I removed it and will have to see if I can get a replacement soon.

I've refrained from painting it--I'm going to save that until I reseal the power cylinder since it will need paint as well.

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