jej3

I am away from all of my tools and garage space and my 1990 928 has decided that turning left is not going to be "power assisted".

Happened yesterday, needed to do a U-Turn on a street and started turning left and it was just plain ridiculous to turn the wheel. Turning right is a treat

So, any up front thoughts on what it might be? Power Steering reservoir is full and while there may be a bit of weeping in the Power Steering system, there's definitely not a full-on leak anywhere.

Can Power Steering rack break down internally and exhibit this OR should I explore some other parts of the steering?

My trip home, later today, will consist of mostly right turns and about 60 miles of driving on the interstate. I expect to jack the car up in the next day or two.

Thoughts?

jej3

Bump

jej3

Any thoughts on really saturating the Universal Joint with WD40 to possibly cure this? Seems to be on the list of a few recommended solutions I see around.

SeanR

Sounds to me like the steering rack has failed. You can check that coupler and see but I have doubts that it's the failure point.

jej3

Thanks @SeanR - All things come to an end. I know Roger and Mark both carry rebuilt racks. If the rack is getting replaced that will start a very long list of projects

Rack
Power Steering Lines
PS Reservoir
Motor Mounts
Oil Pan Gasket
Oil Cooler Lines

Can Delrin Bushings with literally 2K miles on them be re-used on the replacement rack?

Peter North

If it is a unidirectional issue, I would think something to do the rack.

SeanR

If you aren't worried about the cost, do it like the '85 I've got in. All of it. Reservoir, pump to res, res to cooler, pump to rack, rack to cooler, tie rod ends (inner and outer), boots and forget about it for a decade or two. I'd not put the delrin bushings in on a newly rebuilt rack, the new bushings are great, and smooth.

If you are going in to do the pan gasket and engine mounts, think about doing the front shocks also since that job will be 1/2 done.

Fsharp9

Your car is protesting NASCAR

GregBBRD

Inside the steering rack, there's a shaft which twists, from the resistance of the tires. This shaft, when it twists, opens a valve (spool valve) in the main body, which directs fluid to one of the chambers on the rack.

Several possible things can happen....one is that the valve no longer opens (rare) or secondly there is a small piece of dirt, debris, or varnish which gets caught under the valve, not allowing it to seal (more common), or an internal seal has failed on the actual spool valve assembly (not very common, either).

Here's what you can try.

1. Change the fluid and the filter. Suck out as much of the old fluid as you can. Fill with new fluid. Start the car and circulate the fluid. Move the steering from lock to lock. Shut off and suck out the mixture of old and new fluid. Repeat until you have perfectly clean fluid. Change the filter after the fluid is clean. Use the proper Dextron fluid....it has cleaning properties.

2. Turn the steering wheel all the way to lock and then "force" the internal shaft to twist (you will feel this as a "spring back" feeling, right at the lock....and should hear the power steering pump start to complain.....and the main pressure hose will deflect.) This will force the spool valves to open as far as they possibly can....and if there is a chunk of debris, it may become dislodged.

SeanR

Greg, are you saying to change the reservoir each time?

GregBBRD

No. Just once.

I always assume that the filter isn't compromised and leave the original filter in place until I'm confident that the fluid is clean and change it at the very end of the process.

If there is any sign that the filter has ruptured or is compromised....it would probably be better to change it when the first of the fluid is removed. If this is done, I'd loosen the feed and return lines at the rack, to get rid of as much fluid as possible.

jej3

Thanks, Greg and Sean. Plenty to think about. Out of curiosity/frustration, I unlocked the steering but didn't start the car yesterday before my trip home.

I then proceeded to work the steering to full left and full right lock. Heard more of a pronounced click at the end of full left lock.

Started the car to drive home and to my surprise not one iota of stiff steering the whole ride.

I will be keeping an eye on this and going back through the stack of receipts I have for this car to determine if the rack was ever changed out in 160K miles.

Your input is super valuable and very much appreciated!

jej3

My immediate thought too as I was about 10 miles from Daytona when the issue started

rotenDrachen

Interesting. My son and I are sorting through a new 83 s and it seems there is some "stiction" when the wheel is moved left from center. We have no history on the system, or rest of car. All I know about the power steering system is that some sort of red fluid is at the right level and it doesn't leak. We were planning to replace the reservoir and lines and service with Castrol Transmax Z.

The method GregBBRD outlines above makes sense for 'cleaning' the system. Any hydraulic system will collect dirt if it's air vent to reservoir isn't filtered and rubber dust from the inside of old hydraulic lines. This contamination gums up valves very well. Just because a hydraulic line isn't leaking doesn't mean it's not breaking down inside and contaminating the system. I've dealt with maintaining aircraft, and the service life on a rubber hydraulic hose was limited to ten years for this reason.

Ed Scherer

Just had the exact same problem described in the OP yesterday. Problem cleared briefly after doing a full-lock left turn into a parking garage, but returned (and stayed) today.

Rack was replaced with a rebuilt ZF 13 months ago and has worked fine until yesterday.

jej3, what ever happened with this? Did the problem ever return?