Power assist piston

[Lin]

In going through my steering system, it was found that the power assist piston, can be compressed and extended by hand if the engine is not running.  Is it supposed to do that?

[pvcces]

Hi, Lin.

I think that the power steering is an open center hydraulic circuit. This type is used in order to prevent power loss and heating of the hydraulic system when not needed.

When you turn the wheel just a bit, hydraulic fuild is directed to one side of the power assist while the other side is directed to the return. It doesn't take very much movement to get full assist.

As you release the wheel, the supply feeds right into the return, and there is no more assist.

To find out if the valve leaks, get a helper to turn the wheel slightly while pressure is applied. You will probably get some movement in the gear. Be careful to stay out of the way of the gear.

Good luck.

Tom Caffrey