Hi guys, I installed a factory 96-97 Magnasteer rack from a 96 Bonneville in my Lesabre yesterday. It has much firmer valving than my old-man overboosted factory Buick rack had, plus running the Magnasteer rack with no magnasteer controller makes low speed driving even firmer. Anyhow, the only problem I have is that I can't get all of the air out of the system. I jacked the car up, filled the system, and turned the wheel back and forth around 40 times w/ the reservoir cap still off, and the car not running. I then topped the fluid off and reinstalled the cap. After several 20 minute drives, the fluid has tons of tiny air bubbles in it, and every time I remove the cap after driving it blows air pressure out. The steering shudders when I turn, especially as I approach full lock in either direction, and if I turn the wheel with the car stopped, idling, the pump groans sllightly more than normal. All signs indicate that, obviously, I still have air in the system. The O rings looked good when I reinstalled the hose, but I suppose they could be crushed enough or dirty enough that they are allowing air in somewhere. Has anybody installed a rack or pump on these cars and had any difficulty bleeding the system, or is there a trick I haven't tried yet?

I've replaced hoses and pumps. To bleed the system, I've let the motor run with the PS cap off for about 10 to 15 minutes, or until there are hardly any bubbles to be seen. It seems with the cap on there isn't enough venting.

I notice in the service manual that GM does Not recommend turning the wheel from lock to lock while bleeding.

Cheers,

Excellent! This is exactly what I was hoping, to find out there is a better way to try to acomplish what I failed at. I will do as you suggest tomorrow morning, and hopefully I get all the air out of this thing. I was following GM/Saginaw online instructions for turning the wheel lock to lock with the car off to bleed. My Haynes manual said to do the same. I really hope the stuipid O rings are OK, not that its a big deal to change them, but messy since the system is full.

as a side note.... it is important to flush all the old fluid out of the pump before installing a new rack. you dont want contaminated fluid in the new rack.

Hi guys, I let the car idle for 20 minutes with the cap off, and I also cranked the wheel lock to lock with the cap off. I have no bubbles in the fluid. I still have air in the system, as indicated by shuddering power assist across the whole range of turning the wheel when I'm driving. Or I wonder if this damn pump is bad (with 72k miles of course. I really should have sold this car a long time ago and bought something new and foreign.) After a short drive, I popped the cap and it did not have any contained air pressure. The fluid also looks good. Is it possible I just need to put some miles on the car to get the rest of the air out? Is the p/* pump cap vented such that it will blow off air pressure that leeches out of the fluid? I know it has a conical spring in the center, but I wasn't sure if that is a calibrated blowoff like a radiator cap, or if it is simply there to maintain contact pressure on the rubber gasket.

After the dealer had replaced the rack because of failure, their new install did shudder when you steered to the right only, even after a couple thousand miles of driving. Either this is a coincidence and they somehow didn't bleed the system properly (and it doesn't self bleed) or my pump was damaged from the rack failing and now it needs to be replaced. I did notice that even with the dealer replaced rack I would get occasionally sporadic assist, ie cornering with the wheel turned slightly, occasionally the wheel would kick back towards center, probably due to a short lapse of pressure from the pump.

Argharghargharghargh!!!!!!!

They recommend that you dont go lock to lock.....it does take a while to get rid of the bubbles..

Several genuine GM sources have said going lock to lock is fine. It'* not recommended to hold the steering at lock though, that could cause damage. I was careful not to bang the wheel off the locks or hold it there. Will the remaining air bleed itself out during normal driving, or should I take the cap off and start cranking the wheel again?

I would think you have the air out by now, as you mentioned there are few if any bubbles left in the pump reservoir.

I would start looking elsewhere, either the rack is defective or your pump is toast.

Cheers,

I'm going to cry if this rack is defective, I will sell the car before I change another rack. This rack has 70k miles on it, did not have any leaks, and turns smoothly without the car on. Power assist is what is shuddering right now. I have only put 15 miles on the car since I installed the rack, all highway. I haven't needed to drive anywhere. so it'* not like I've driven 500 miles and there is still air in the system. I guess changing the O rings on the lines is in order first, then replace the pump.

Just a thought....possibly a weak tensioner? Under load the belt slips on the pump pulley, causing power assist issues?