Lower ball joints in the CDI (MB branded) had been in there for 100k miles. One of them started making noise so I had my mechanic replace both of them....Lemforder.

As I'm driving the car, the steering somehow seems to be slightly stiffer than it was before. Nothing dramatic, but I notice that the car doesn't seem to be as quick to self center after a 90 degree turn as it was before.

Any idea what to make of this? Is this just par for the course with new vs. old ball joints? Could it take a little while for them to "loosen up" a bit?

From my W124, I know there's relationship between ball joints and self-centering. In that case ball joints weren't making any noise at all and seemed to be intact. But the car wouldn't self-center properly. Replacing ball joints solved the problem.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Did the mechanic perform a front end alignment after replacing said ball joints? If not, he needs to do one. Self-centering is a function of alignment.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

No...he doesn't have a machine. While it could certainly be the case that the car could use an alignment (although it doesn't pull one way or the other), I wasn't under the impression that an alignment was needed after ball joint replacement. But perhaps I should get the alignment done anyway.

In the case of my W124, the self-centering problem was SOLELY a matter of the ball joints binding. Here's the thread from seven years ago when I was trying to figure that one out. http://www.peachparts.com/shopforum/diesel-discussion/306774-what-would-account-steering-having-difficulty-returning-straight-position.html

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Most ball joints have a rubber o ring under the socket to preload the joint. As the joint wears, the rubber expands to take up the space. At some point joint wear / aging of rubber causes the joint to loosen up.

Fresh ball joints have higher friction than worn out ones so centering might not be as rapid. As long as you are not having to steer back to center and car does not dart when wheel is straight, I'd call it good however an alignment check is always a good idea.

Get actual pre and post alignment numbers and be sure to tell _the_ alignment tech you have no problem paying for an alignment even if everything is in spec and no adjustments are needed. The tech needs to feel comfortable that customer isn't going to scream at the service writer " I'm not paying _anything_ because your tech _didn't do anything_ " ( . . . to adjust the car ) .

That makes sense....sounds like most likely explanation of what I'm experiencing.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

My 2006 CDI started to squeak, replaced with MOOG Problem Solver ball joints with zerk grease fittings. Did an alignment and it feels exactly as before.,no difference.

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

One forum member noted that, when he rebuilt his W211 front end, the steering was noticeably tighter until he put some miles on the car. I'll be putting a lot of miles on the car over the next week...so we'll see.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

Interestingly, lots and lots of people out there on automotive forums who've experienced the same thing (stiff steering after ball joint replacement). So at least I'm not alone.

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14 E250 Bluetec "Sinclair", Palladium Silver on Black, 153k miles
06 E320 CDI "Rutherford", Black on Tan, 171k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver, 142k mi, wastegate conversion

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

The 211 that my neighbor used to have, had a radius rod with a ball joint on the steering knuckle. If I had a stiff steering problem I would check that ball joint, and probably inject grease into it with a grease needle.

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'97 E 300 D