Power Steering Control Valve

[Erv M.]

Someone told me that the usual culprit of a leaky steering control valve is caused by over greasing the zurc fitting thus damaging the seals.

Is there any truth to this?

[John H.]

Re: Power Steering Control Valve

Someone told me that the usual culprit of a leaky steering control valve is caused by over greasing the zurc fitting thus damaging the seals.

Is there any truth to this?

In many cases, yes - that's why there's a warning card included in the box (or printed on the box) that says not to grease the valve at the zerk fitting or it'll void the warranty. Most valves these days have a plug in that hole instead of a zerk (I know Lone Star's do).

[Jim S.]

Re: Power Steering Control Valve

According to my control valve assembly drawings (up through 7825636) all valves had zerk fittings and a ball stud seal with a purge slit to allow excess grease to come out.

I was supervisor of the hose and seal group at Saginaw Steering Gear in the 70s through mid 80s. I can vaguely remember the zerk being removed but can't pinpoint the year (whether during C3 production or after C3 production).

From the assembly drawings (up through 5695636) I can only conclude that after production ceased and the valve was low service production it was decided that with newer greases available at that time, the zerk fitting on the valve could be eliminated, the purge slit removed, and the valve advertised as "greased for life." Possibly as a service item, the drawings weren't meticulously kept up to date.

All of the control valve assembly part numbers and drawings through the years show a zerk fitting. The last control valve assembly part number that I have is 7825636 (first used on the 1976 Corvette). It has a zerk fitting.

If Joe Lucia can find a later control valve assembly part number than 7825636 maybe we can track the zerk history further.

An yes, I have noted a number of cases where the control valve leaked power steering fluid after being greased through the zerk fitting.
Jim

[Wayne W.]

Re: Power Steering Control Valve

I dont think greasing had much to do with the failures. The design is just prone to failure. I have built thousands over the years and I have never seen one that I thought was damaged by grease. I have seen grease mixed with the fluid, but the seals were not damaged and should have sealed even with grease in there. Fact is every three or four years, you are going to have to refresh those seals whether you grease it or not.

[Joe L.]

Re: Power Steering Control Valve

According to my control valve assembly drawings (up through 7825636) all valves had zerk fittings and a ball stud seal with a purge slit to allow excess grease to come out.

I was supervisor of the hose and seal group at Saginaw Steering Gear in the 70s through mid 80s. I can vaguely remember the zerk being removed but can't pinpoint the year (whether during C3 production or after C3 production).

From the assembly drawings (up through 5695636) I can only conclude that after production ceased and the valve was low service production it was decided that with newer greases available at that time, the zerk fitting on the valve could be eliminated, the purge slit removed, and the valve advertised as "greased for life." Possibly as a service item, the drawings weren't meticulously kept up to date.

All of the control valve assembly part numbers and drawings through the years show a zerk fitting. The last control valve assembly part number that I have is 7825636 (first used on the 1976 Corvette). It has a zerk fitting.

If Joe Lucia can find a later control valve assembly part number than 7825636 maybe we can track the zerk history further.

An yes, I have noted a number of cases where the control valve leaked power steering fluid after being greased through the zerk fitting.
Jim

Jim------


The GM #7825636 is pretty much "end-of-the-line". In fact, it's still available from GM (for about 635 bucks, GM list). When it's finally discontinued, I would not expect a supercessive part number.

However, I don't know that the 7825636 which is available today matches the blueprints in every way.

[Joe L.]

Re: Power Steering Control Valve

I dont think greasing had much to do with the failures. The design is just prone to failure. I have built thousands over the years and I have never seen one that I thought was damaged by grease. I have seen grease mixed with the fluid, but the seals were not damaged and should have sealed even with grease in there. Fact is every three or four years, you are going to have to refresh those seals whether you grease it or not.

Wayne-----

I expect that part of the problem involves the fact that "these valves work pretty hard".