Calo69

Problem occurs when car is stationary and i turn the wheels. Wheels turn with more than normal effort causing a pulsing, vibration that transmits to steering wheel.
New pump, control valve, belt, hoses.
Steering is great when car is in motion, no play in wheel, tracks straight, minimum effort both direction, responsive with a good return.
Only when stationary on ground does problem occur.
Thanks in advance

A88FXRS

pump pressure could be low. should run @ 1100 psi under load.

OldCarBum

It could as simple as the tire width, type of rubber, or how much tire is in contact with the road when stationary. Park on a garage floor that is really smooth and give it a try then wet the garage floor and try it again, pull the car out onto the rough asphalt and see the difference. My brand new Chevy 4X4 with off road tires does something similar ever since I changed from the stock tires. May be nothing.

Calo69

Thanks, i'm guessing either flow or pressure, hoping some had same symptoms before i put a gauge on it

Calo69

Thanks but tires are same a before changes and did not have problem previously

speedreed8

did you change out the flow control valve from the original pump to the new pump, i think corvettes had a special valve in the pump. Jim Shey has an article and other threads on this.

Calo69

No, just used one that came with pump, gave all info on car to my parts guy to order

OldCarBum

When I purchased my '73, the prior owner just replaced the power steering pump and all components. I took it to a Corvette specialty shop and had them do a full safety inspection on the car and one of the items they documented was that the high pressure line was leaking and that the pump and components were generic for a Chevrolet, however they were the incorrect parts for a Corvette. They showed me the difference in the pump, lines and other components and told me this was a common mistake made when owners order the replacement parts through a parts store rather than through someone who specialized in Corvettes. I ordered the new steering components and pump and had them installed.

Calo69

Thanks,
Valve and hoses i know are corvette specific, pump was supposed to be also, i will have them double check pump specs to make sure it is correct also.

Calo69

Double checked, pump is correct application. To the testing board.

divotdug

A couple months back I replaced the pump on my '76 Camaro. Had the exact issue with the replacement pump. Turned out the new pump was bad and needed to be replaced......how I hate swapping that PS pulley.

Calo69

Thanks, i was hoping someone had exact symptons, my pulley is easy, no puller needed just a keyway with a nut.

I spoke with a rep from cardone,said if i revved in neutral and assist was good then the power valve is sticking, assist got much better so maybe i can check that out, i'll test pressure also.
Just PIA for out of box part.

Jim Shea

I was just going to ask if increasing the idle speed to 1500 or 2000 rpm provided more assist while the car is stationary. Increasing the idle speed would increase the flow from the pump and might indicate a pump that is not to spec.

The one component that you didn't replace was the assist cylinder (aka ram). If the ram was worn out, (i.e. there is a plastic piston ring inside the ram that seals against the inside wall of the cylinder.) If that ring was worn and caused leakage (inside the ram) to the point where the system required more flow, it might be the cause of your problem. BTW, the ram is a welded assembly and you cannot service that plastic ring.

BTW, I am not sure what the "power valve sticking" means. If the Cardone man is saying that the flow control valve inside the pump is sticking, then he has supplied you a defective power steering pump. There is a slide valve inside the pump (just behind the one inch hex fitting). You should be able to remove the power steering hose from the fitting. Then unscrew the fitting to remove it. You should be able to use a small screw driver to push on the slide valve that is right behind the fitting. You should be able to press on the valve and feel it compress a spring and it should easily slide inside the pump bore. That is a requirement for a brand new, rebuilt, or an old well functioning pump.
Jim

Calo69

Thank you Jim,

I didn't change it because system was working good until problems with control valve and pump came up, maybe those problems were related to ram, any way to check proper operation ? Seems like the kind of problem that can look like its' working but just not strong enough to do proper job. Might as well change anyway.

Thanks again

7T1vette

Have you verified that you have the proper amount of P/S fluid in the system? Correct symptoms for low fluid condition...

Calo69

Yes, started with that, hoping for simple solution, no luck.
Thanks

7T1vette

Most likely candidates:

'Skipping' P/S drive belt when under load (try scuffing the drive sides of the belt with Scotchbrite pad); wrong drive belt (face angles wrong for GM pulley); worn out P/S pump (internal leakage); weak/damaged P/S pump relief valve.

Good luck with your investigation & repair.

Calo69

Thanks, i had scuffed up pulley with an abrasive, but now after drive this morning i was in middle lane with cars on both sides and i was able to pick up on some belt squeal for first time, belt is new, correct and tight. I will re-address pulley tommorow.
Thanks again