What would account for steering having difficulty returning to straight position?
 

As I continue to observe my power steering, I guess what I'm observing is as follows: The wheel turns fine when I'm turning INTO a turn. But when I relax my grip on the wheel having made the turn and want the wheel to straighten out, I notice that I'm having to turn the wheel back into the straight position....as opposed to its doing it (mainly) by itself.

My parts guy suggests steering damper. A forum member suggests pump or gearbox. What are anyone's thoughts? It's a 1991 300D.

Thanks.

When I have steering issues, its usually the alignment.

Lower ball joint seized. I've seen more than one.

If it were a ball joint, wouldn't I hear something (like typical ball joint creaking)? Or not necessarily?

In general, caster gives the steering its tendency to return to straight ahead. I go with those who suggest component wear or binding resists the self-centering force if it developed over time. Most MBs of that vintage should have the wheels aligned with the steering box locked. Too many shops align to the steering wheel which might have been repositioned during a previous alignment or other repair.

Sixto
87 300D

A binding ball joint probably won't bind with the front wheels off the ground but a steering gear or damper will. Don't count on a ball joint to make noise. Check for stiffness when returning to center with the front axle off the ground with the engine running and not running because a hydraulic issue in the gear could cause this in addition to gear mesh being adjusted too tight.

Caster does affect return-ability to center. More caster means more tendency to stay on center. 123's and 124's are spec'd with so much caster that the caster angles would have to be a mile off for return-ability to become an issue.

your car needs a correct mercedes alignment done with steering box lock and spreader bar on the wheels. The alignment on W124 seems voodoo to some sears type shops - change one setting and something else goes out.

I learned about steering issues on a diesel ram. Steering threads for those trucks are surpassed only by cracked dash and injection pump threads. Return to center issues can be either hardware or adjustment. The only way to differentiate is to go through the hardware then adjust. The $8/hr monkeys assigned to the machines can't think outside of the box & usually don't understand how the variables relate.

I never ask for an alignment. Instead, I say that the vehicle is doing xxx & ask them to diagnose and price the repairs. If they diagnose alignment as the problem, I won't pay unless it fixes the problem. In other words, buy the hole, not the drill bit.

What kind of container do I need to transport the hole when taking it home ?

I agree with that.... but sometimes it is easy to just set the toe in... that by itself can produce this symptom...

You need at least a 1 ton 4x4 straight shift - diesel of course, preferably with Cummins 12V. Anything else may have trouble climbing the hills.

One can set toe with strings, jack stands & propre drill bit used as a feeler gauge. Good enough for Gubmt work but better used when you know everything is in good shape else you'll be questioning your toe setting.

I opt for lifetime Firestone alignments so I can use their machine frequently with impunity.

I have seen an improperly adjusted steering box cause this too.

X2
An over tight steering box will do this.
Why was it over tightened? Normally because the worm is worn in the straight position & been tightened. when it is away from straight it is too tight.
I lean towards the castor being out being the more likely cause. Positive camber can also reduce return.

I agree. And with that said we do not have the information letting us know if an attempt was made to adjust it prior to the issue.

By way of an update, my indie is looking at it right now and is a bit perplexed. He says it looks like the steering box has never been adjusted....still has factory paint. Says all suspension components look good. Pump is fine. I think next he's going to look at the steering damper.

He doesn't do alignments, so if he continues to be stumped I think I'll get it aligned somewhere else and then see where things stand.

Does the steering box on its own have a tendency to center? If not, what's the point of the alignment locking pin?

Sixto
87 300D

unbolt the steering damper, throw it in the trunk and drive around to see if the problem goes away.

Interesting....that's exactly what my indie said he was going to do next.

Apparently steering damper is fine....I guess I'll go get the alignment done.

Not enough caster will cause this.

Haha....the authoritative young man at the alignment shop assures me that alignment being off could NOT cause my symptom. We shall see....

Interesting....the alignment shop found that when they disconnected the damper the problem went away and thus recommend replacing the damper (for an outrageous price, I might add). My indie, who took the damper off and inspected it, contends that removing the damper could simply be masking the cause of the problem, which he suspects to be the alignment. So, I'm just going to get it aligned; and, if that doesn't solve the problem, then I'll replace the damper.

Alignment shop wanted to charge me $117 for the damper...just for the part!

I want a lot of things. Don't always get them but it never hurts to ask - unless I get slapped.

The whole package.

If you brought the car this way. Checking the steering box for being set up too tight is important. They can fail in service if done that way. In your case I would loosen the adjustment nut and turn the screw inward a precise turn on the steering box .Tighten the locknut a little and go around the block. If it is centre returning somewhat better adjust the screw in a little further. If no change then return to the previous setting.

The correct way from my perspective is the sector should just present a small additional resistance when passing through the centre area of the steering. If you have heavy resistance in the centre and still fair resistance turning off centre with the wheels in the air something mechanical is amiss.

If you have a pitman arm puller or a way to disconnect the linkage from it the steering box. This can be checked out better. Also if the pitman arm is diconnected from the linkage you can check for binding easier usually.

Even tie rod ends will bind on occassion. With one guy turning the tire side to side. Another guy watching and examining joint movement might pick it up.

Of course it could also be alignment but it would have to be quite a long way off I imagine. Someone might have cranked the castor out or a really poor alignment shop perhaps. There are some real clowns working out there on cars for a living.

agree.

Since it looks like I'll have to get the alignment done at the dealer ($150), I'll just go ahead and replace the damper first just for the heck of it. At least rule that out as a possibility....can't hurt to have a nice new damper.

The thing I don't get about the steering damper explanation (and apparently the problem DID go away when it was removed) is how a bad damper would account for the symptom of not centering. When dampers go bad, don't they get "looser?" Do they ever tighten/stiffen with age? Maybe that's my problem.

Not normally but it could for example be binding. That would be unusual as normally they lose or reduce their shock absorber type action with wear over the years. As your logic suggests.

This basically is having hardly any resistance pushing it in or pulling it out. It almost sounds like yours has developed far too much resistance to movement. Like it somehow at one time jammed internally and bent the shaft enough to create problems. Or a valve internally is not opening when it should. So now the effort required to move it is excessive. An internal seal out of its groove or whatever for example is a sane possibility as well. The seal between piston and cylinder in there could be the culprit.

Replaced the damper this morning. Still won't self-center. But I guess, after 20 years, I'm happy to have a new damper.

So now it's off to the dealer for an alignment. It's a great dealer as dealers go....but I still feel like I need to brace myself for all sorts of recommenced repairs I don't need.

So here's my question: if it's not the damper (just replaced it) and it's not the alignment (we'll know soon enough), what could it be? If, when the damper is removed, the self-centering problem goes away, that would seem to indicated that something else is binding, but to such an extent that it's only symptomatic when the damper is installed.

What are some possible/likely candidates as to something else that's binding?

X2 on the ball joint... Mine broke off in the grocery store parking lot this past Friday. Had the same symptoms.

Hmmmm......I have wondered about ball joints (mine are original). About a year ago, I heard what sounded like ball joint creaking. But it went away. I took it to my indie anyway and he indicated that they were fine. He essentially had a blank check to repair them but said they were OK. I have not heard the noise since. But now I wonder....

Based on what everyone is saying, it could be most anything. But I would recommend having your indie (or someone you trust) re-check the ball joints just to be sure. Broken ball joints can ruin your day. See your other thread about ball joints.

That does make sense. This is really frustrating. I wonder if the ball joints can LOOK and FEEL fine, but nonetheless be causing a problem with the steering. When the steering damper is removed, the problem goes away. But it is NOT the steering damper; I just replaced it.

On two different occasions, my indie has looked at my ball joints; on both occasions, I've gotten a clean bill of health. I wonder if I should just replaced them on the ground that they're 20 yrs. old.

I was all set to take it to the dealer....I think I'll back out of that.

Yup, I discovered that this summer when my '79 wagon lurched over on a steep uphill curve and the car dragged to a halt as I quickly found a place to "pull over" ha! :eek::eek::eek::eek:
The RF wheel was cocked sideways, at about a 45 degree angle. Luckily there was no other traffic on the 2 lane road and it was a place that cars could pass without endangering each other.

The ball joint had been groaning, telling me hey! replace this thing before it kills you !!!
DDH

An update: had an alignment done at a local alignment shop. My theory was that, even if they couldn't do it perfectly due to the lack of a spacer bar, they should be able to get it close enough to reveal whether the alignment was the cause of the problem. Unfortunately, the self-centering problem persists.

While it's possible that the problem is still related to alignment and that I'll have to get the dealer to do it, my current suspicion is that there's something in the steering system that is binding. My next stop, wanting at all costs to avoid the dealer if possible, is the best independent MB tech in the area....it's a bit of a drive which is why I don't usually go to him.

That's all for now.

Yes, they can.

That's what I'm betting on, then.

Disconnect the drag arm from the pitman arm. It could easily be a steering box where an owner overtorqued the adjustment in an attempt to cover slop. Does the adjustment screw area look like it has been bothered before?

This enables you to move the steering parts from side to side to attempt to identify or establish if there is a bind somewhere else as well. Changing parts just on suspicion usually is not too productive.

Adjustment screw has never been touched....still has factory paint.

I do not see how the independant mechanic could have determined if you had a seized ball joint or whatever with the pitman arm hooked up to the linkage. By nature a seized ball joint or tie rod end type of joint will usually test tight. Even tie rod ends and others can seize remember.

With the disconnection you can find it if it is there. With the wheels off the ground the system should traverse fairly easy without the steering box hooked up. If not close observation might identify the fault. Technically even if the steering box has not actually been adjusted it may have a form of failure as well. This you would notice when it was disconnected .Hard to turn. It is simply a divide and hopefully conquer method as well.

If the alignment shop gave you a printout you want to see if the castor angles where not a long way off what they should be. They are the principal drivers of aiding the return centering. Adjusting the lower bars length determines the castor. Again on many newer cars the only real adjustment left for alignment shops is basically the toe in unless they change parts. The three axis adjustments are still there on mercedes older cars.

Since many alignment guys do not deal with castor on newer cars he may not understand this. For example if someone changed those two bars at one time and did not adjust them properly could do it but the car would have a difficult time steering straight requiring too many corrections constantly if way off.

So if you know the recommended castor check it against his printout. I noticed even my alignment guy ignored the castor readings on his machine. Technically one side was out enough it should have been corrected. I suspected he did not realise that mercedes had an adjustment for it. Or was just too lazy to do it.

In terms of the indie inspection, I'm beginning to suspect that he too quickly concluded it was an alignment issue....although it still may be.

I don't have a high degree of confidence in the alignment....caster angle is 9.8 left and 10.7 right both before and after, both within range I'm not even sure they did or could adjust it. But in fairness to them, they acknowledged at the outset that they weren't confident that they could do it exactly as it needed to be done.

But it seems like disconnecting things is certainly in order.

Here's a scary story: in researching this, I talked to a first-rate MB tech in PA (Fred's Foreign Cars in Kennett Square). When I told him I was becoming more and more suspicious of the ball joints, he said one time he had his daughter's car....he had looked at the ball joints and they seemed fine. He was driving down an alley at 5 mph and one completely fell apart. So he, even as an experienced professional, missed it...thankfully he was only going 5 mph.

the way I see it is you have either a :

- steering box failure
- ball joint / suspension aged too much

I dont see an easy or inexpensive way to diagnose this from here - the springs have to be compressed and removed and the UCA needs to be released from the spindle. Then you could really feel the lower ball joint and see if it is seized, or loose or what have you.

At that juncture, you might as well replaced the lower ball joint and everything else around that looks worn, whether it is showing signs of wear or not.

I believe lower ball joints are 3 hours of time at the shop each.

Makes sense....with a 20 yr. old suspension, I just want to replace anything even questionable. I'm cheap, but there's just no sense in pushing suspension items to the outer limits of their useable life.

FWIW, I got my car back from my indie & went on two 200+ mile round trips in the last two days. My steering problem vanished with the new ball joint. The car handles a lot better, too.

Indie said I will need to replace the other one soon. This one was $90 for the part & about 2 hours labor. He said there is a way to check the joints, but it involved getting the car on the lift & taking the pressure off the springs. He didn't go into any details, but he's been doing this for over 20 years & knows what he's doing.

I still have one of the rear bearings screaming at me, which needs to be replaced soon. Then I'll see about the other ball joint.

Good luck with your issue.

FINALLY, a definitive diagnosis: BALL JOINTS. Being replaced today.

Struts are weeping but not leaking. Will hold off on that for the time being.