01-10-10, 10:39 PM
While pulling into a parking stall today in my '97 deville, I had the steering at full lock up and all of a sudden something happened and steering wheel started jerking and started getting loud pulses from the power steering res., I straightened out the wheels and the pulsing "almost" went away, but everytime I tried to turn the wheels it came back with a full vengance. Drove about a mile this way and then shut it down (afraid it would fry the serpentine) and called a tow. searched the archives and couldn't find anyone with the same symptoms. Anybody know what I've got here?
I think there is some sort of pressure relief valve built into the PS pump assembly - maybe your's is messed up - not seating properly? Might need a new PS pump?
01-12-10, 10:20 AM
The P/S pump is a sliding vane positive displacement design. There are bypasses and pressure reliefs built in, but an extended overpressure, such as you describe, can break one or more vanes which then rattles and clanks around in the pump case.
One Cadillac TSB calls for replacement of the steering outlet (return) line in cases of a low speed moan or noise. There's a specific procedure for pump replacement and system bleeding, and you'll need a couple of quarts of GM Power Steering Fluid, NOT DEXRON-III or -VI.
01-13-10, 07:58 PM
Thank you for the replies. I replaced the pump and everything is fine, have to return the old one as a core, so I will never know what broke inside. Beware, because I really didn't that much pressure in the full lock position. I was just pulling into a parking space, but it was at full lock.
NEVER EVER hold the wheel at full lock. You dont have to be holding it against the lock that hard for fluid pressures to spike. If you hit full lock while turning, back off a few degrees, the car will turn the same amount without breaking anything.