Hard turning steering wheel

[Martin421]

Hi guys,
I'm dealing with hard turning steering wheel.
I bought my 500E two years ago, car had been probably sitting idle for a longer time, since all of the rubber parts on front suspension were perished and hard, so the car had just a serious play in steering.
Now all of the bushings, everything like steering pump, steering box had been resealed and idler arm bushing and every possible thing that has any kind of joint or bushing is new, as well as new front shocks.

The front end has now absolutely zero play and steering wheel is amazingly precise but it just don't turn that easy and smooth as it should, it even stay turned when turned slightly from central position and I have to turn it back.
Steering box had been resealed and they probably adjusted some play, at least they thought they did.

So can a too tight adjustment of steering box cause this?

 

[036]

It´s a level control pump. This terribly expensive part is also taking care of your steering......

 

[Martin421]

It´s a level control pump. This terribly expensive part is also taking care of your steering......

Never heard of it, what does it do? That looks like brake master cylinder.
By level control pump, do you mean that combined steering pump that creates pressure for the rear SLS and steering? Or it's something else?

 

[TerryA]

Isn’t that the vacuum booster behind the master cylinder? Does it also run vacuum assist to the steering?

 

[emerydc8]

They probably went too tight on the steering gear. If they adjusted the play and the steering stays in position when exiting a turn that’s likely the cause. That advice came from a senior MB tech. I don’t remember if the threads on the shaft are reversed but you can do a search here and find which way will loosen the nut, then use an Allen to turn the pitman shaft. Just make sure you mark it first and move it in small increments until you are satisfied with the steering. If shaft is too tight it will result in premature wear of the steering gear.

Another thing that could affect power assist is when they sealed the pump they had to remove the small rectangular blades (paddles) in the daisy wheel. If they reinstall these blades with the square edges facing outboard it will affect your power assist. If all the blades are backwards you will have very little or no power assist. You can feel the square edges on these blades with your fingers. They will feel sharp. The square sides go towards the center of the shaft. The rounded sides ride the outboard wall of the pump chamber.

 

[Martin421]

Isn’t that the vacuum booster behind the master cylinder? Does it also run vacuum assist to the steer

They probably went too tight on the steering gear nut. If they adjusted the play and the steering stays in position when exiting a turn that’s likely the cause. That advice came from a senior MB tech. I don’t remember if the threads on the shaft are reversed but you can do a search here and find which way will loosen the nut. Just make sure you mark it first and move it in small increments until you are satisfied with the steering. If that nut is too tight it will result in premature wear of the steering gear.

Another thing that could affect power assist is when they sealed the pump they have to remove the small rectangular blades (paddles) in the daisy wheel. If they reinstall these paddles with the square edges facing outboard it will affect your power assist. If all the blades are backwards you will have very little or no power assist. You can feel the square edges on these blades with your fingers. They will feel sharp. The square sides go towards the center of the shaft. The rounded sides ride the outboard wall of the pump chamber.

The steering pump had been done by myself since seal kit was pretty hard to find and collected the bits from all over the world. I remember those blades (paddles) and I’m 100% sure I installed them correctly by rounded side facing outwards to seal during turning properly. As you say, the other end is really sharp so it was quite logical for me to avoid scratching the surface. So this is done properly.

My bet is too tight steering box as well. I already found the adjustment picture here from another thread, good point with that mark, I’m going to buy a white marker to avoid any big plays and mistakes

Thanks!

 

[Martin421]

After you loosen the nut you turn the shaft with an Allen wrench.
Post in thread 'HOW-TO: Reseal the power steering box output shaft at Pitman arm'
FYI - HOW-TO: Reseal the power steering box output shaft at Pitman arm | "HOW-TO" Tutorial Articles

Amazing! Thank you

 

[gsxr]

I agree with @emerydc8. Most likely the box was "tightened" unnecessarily, however as noted, be VERY careful with this adjustment. IME, the 124 chassis steering boxes almost never require adjustment of any kind. I've only heard of this once or twice over 15+ years on this forum. And, I've never had to touch this on any of my cars (over a dozen different 124's, over nearly 30 years of ownership). It's not something you just decide to do while resealing the steering box.

Far less likely, but a remote possibility, is the lack of pressure from the tandem pump. However, I don't think this would affect the return-to-center issue you are experiencing. That's more likely due to incorrect box adjustment.

@Klink ? Any input on this one?

 

[Martin421]

@gsxr that looks like the only logical way, I’ll do it very carefully and loose it really a tiny bit. SLS works just fine so low pressure from the pump shouldn’t be a problem. The steering box was just as a part on the bench so they tighten it too much. Other than this no leaks from both pump or box so I’ll try this