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Damn I hate this. I pulled the control valve out of my '82 this morning and separated the head from the ball stud body. I was careful to remove the large piston in the right direction, but Bubba has been in here before me. The edge of the outermost cylinder wall is broken off. Based on the photos, does this look bad enough to cause the problem I'm having? Steering doesn't pull, and the wheel is centered driving up the road. However, the PS system only assists in one direction.
Overall view of the head:
Broken edge at top of bore:
Other side of bore looks OK:
Closeup of damaged area:
Does this mean I need to order a new control valve?
The reason I thought this was PO damage is that the instructions say if the piston is pushed out the wrong direction, it will damage the bore. Maybe they're talking about a different type of damage, but I'm pretty sure this isn't just a casting irregularity. Anyway, I'll proceed with the work if you guys think it won't affect functionality. I just didn't want to waste $60 worth of rebuild parts (and my time) on a bad valve.
From: Who says "Nothing is impossible" ? I've been doing nothing for years.
So all those little flecks of steel from the damaged area are from a casting flaw. If so wouldn't you have had it taken apart a long time ago. How old is the valve, I'm guessing 33 years ?
So all those little flecks of steel from the damaged area are from a casting flaw. If so wouldn't you have had it taken apart a long time ago. How old is the valve, I'm guessing 33 years ?
I've only owned the car a month. It's had the symptom since I bought it, and I don't think I'm the first person to open this up. There are signs of previous work on the valve, including tool marks here and there that I doubt are from the factory.
Hey, look what I found on the shop rag after I put the control valve back in the car!
Tomorrow I'll fill the pump and adjust the valve. If I'm lucky, this loose piece had something to do with the problem. If not, I'll replace the PS cylinder next week. I wanted to do them both at the same time, but Advance screwed me. I took the day off work to do this job, but the cylinder I ordered wasn't in the store this morning as promised. The work is only half done thanks to their sloppy customer service.
I suppose you could call it a casting flaw. As in "a piece of the casting has broken off and I found the piece, so the casting is now flawed". I'd say you found the problem 454.
I suppose you could call it a casting flaw. As in "a piece of the casting has broken off and I found the piece, so the casting is now flawed". I'd say you found the problem 454.
Thanks, that gave me a laugh! I regret to say the rebuild didn't fix the symptom. It seems odd to me that the cylinder shaft will move both directions when I adjust the control valve, but once everything is bolted up, there's very little assist in one direction. I did check with the wheels up and the motor not running, and manual resistance is about the same both directions from center. It's also easy to turn either direction if the car is moving. The only thing I know to do now is order a new cylinder and hope for the best.
I'd be interested to see the mating edge of the valve that fits in that bore. I could be mistaken, but it looks like someone tried to beat that valve into submission during its last assembly...and the edge of that land in the valve body got broken in the process. [The body casting is relatively soft material, compared with the valve that is case hardened.]
If you see some distress on the leading edge of that valve, there's your problem. And, in that case, the main body and the valve [at the very least] are trashed and must be replaced.
Last edited by 7T1vette; Dec 25, 2015 at 11:21 PM.
There is a flat washer and a spring that sits against that broken edge. If the washer still sits flush and doesn't ****, you should be all right.
In this cutaway of the valve, your broken casting bore with the flat washer and spring are where Spring A is identified. There are not any rubber seals that would come in contact with that edge.
Would it be possible for a leaking seal inside the power cylinder to cause this problem? Maybe a seal that's working well enough to push the shaft back and forth in response to the control valve, but not sealing well enough to create the force needed under load?
Normally if the piston seal in the cylinder were to fail, the rod would extend but not retract under pressure. Since you are able to do the centering of the valve and get reaction in both directions, then it seems unlikely the cylinder is bad, but I would rule out valve issues first. If you have a way to plug one of the ports at the cylinder, then see if the cylinder can be pushed in or out it would tell you if fluid is able to bypass the piston seal. You should be able to find a plug for the inverted flare fitting at the local parts store or get creative.
Normally if the piston seal in the cylinder were to fail, the rod would extend but not retract under pressure.
I think that's what it's doing. If I'm visualizing this correctly, the rod extends when turning left. That's the direction the system provides assist. Turning the wheels to the left is easy, turning to the right is hard. What a PITA. I should have done what I was planning, replace the whole system, but Nooooo... I had to be smart and do it one stinkin' piece at a time. Save $50 here, $20 there, meanwhile the car sits in my driveway while the tires rot away. My life if gonna be Hell if I do the entire car like this.
EDIT: Decided to reorder a rebuilt cylinder, this time through O'Reilly. If the forecast is right, I'll be able to change it out in a few days. I'm about 80% sure the cylinder is the problem, and that it's something inside that I can't rebuild myself.
PS Control Valve Head - Is This Broken?
Thanks, that gave me a laugh! I regret to say the rebuild didn't fix the symptom. It seems odd to me that the cylinder shaft will move both directions when I adjust the control valve, but once everything is bolted up, there's very little assist in one direction. I did check with the wheels up and the motor not running, and manual resistance is about the same both directions from center. It's also easy to turn either direction if the car is moving. The only thing I know to do now is order a new cylinder and hope for the best.
