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1992 300E 2.6
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Discussion Starter #1
So I have a weird vibration at speed that only occurs in the mornings when the car is cold. It does not occur at any other time of day or condition. It feels like a wheel vibration/a heavier weight being thrown around that dissipates after a few minutes of highway driving.

I just put new tires on yesterday thinking that was the cause since they were old and had dry rot. Could it just be flat spots in the tires? Never had this issue in any of my other cars before and not sure if it’s something that maybe known to the forum.

Any help is appreciated.


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W124
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Good move replacing the tires and eliminating them as a cause. Overnight is too short a time for new tires to develop a flat spot. Have you gone through the flex discs on each end of the driveshaft, looking for cracks in the rubber or other indications of age?
 

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1992 300E 2.6
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Discussion Starter #3
Good move replacing the tires and eliminating them as a cause. Overnight is too short a time for new tires to develop a flat spot. Have you gone through the flex discs on each end of the driveshaft, looking for cracks in the rubber or other indications of age?
I know at least one of the flex discs was replaced before I got the car, at a MB dealership if I’m not mistaken. I’ll look at the service record when I get off of work. It’s just odd that it’s only when it’s cold out and the car is cold in the mornings.


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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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When you say "only when it's cold out" what sort of ambient temps are we talking about? If it is really cold, the engine will spray extra fuel into the engine by way of the cold start injector.
 

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1992 300E 2.6
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Discussion Starter #5
When you say "only when it's cold out" what sort of ambient temps are we talking about? If it is really cold, the engine will spray extra fuel into the engine by way of the cold start injector.
The cold start is working fine and is not the issue. It’s only when I get up to 50 MPH or better that this vibration exists, after about 5 minutes at speed, the vibration goes away. Temps ~35 or lower.


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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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What kind of tires are currently on it and how old are they? These cars tend to work best with Michelin tires or similar premium tires. No Wan-Li or LandSail garbage.

Edit: Just reread the thread and see you have new tires. Unless the tires are defective, it is possible that they aren't balanced properly.
 

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1992 300E 2.6
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124 Posts
Discussion Starter #7
What kind of tires are currently on it and how old are they? These cars tend to work best with Michelin tires or similar premium tires. No Wan-Li or LandSail garbage.

Edit: Just reread the thread and see you have new tires. Unless the tires are defective, it is possible that they aren't balanced properly.
The thing is, I replaced the old tires because I figured they we’re the cause....about 9 years old and dry rotting.


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1995 e320ce. 1993 230 TE. 1987 Kit car with 260e running gear.
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When did you last clean and gap your spark plugs?
Have a look inside your distributor cap for condensation.
 

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1992 300E 2.6
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124 Posts
Discussion Starter #9
When did you last clean and gap your spark plugs?
Have a look inside your distributor cap for condensation.
All brand new about 4K miles ago, but it’s not an engine issue. Runs great and has the right power. It’s only when I get up to speed for 5-10 minutes first thing in the morning if it was cold overnight. It is not present after that.


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1995 e320ce. 1993 230 TE. 1987 Kit car with 260e running gear.
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Any issues with wheel bearings, particularly the front?
 

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2003 G500, 2000 SL500, 1995 E320 Cabriolet, 1980 TR8
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I had an issue similar to yours. Turned out to be an issue with one of my new tires (it was out of round - the tech showed me on the balancing machine). They were Hankook which is certainly not Michelin. My best guess is that the out-of-round was more pronounced when the rubber was cold and less pliable but as tire rubber warmed up, the increased pliability allowed the high spot to give as it went under load. Tire dealer replaced that tire and all was well.

Addendum - These days I think the manufacturing quality for tires in general has declined, so at a minimum, I think it's always best to invest in a good road force balance.
 

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1992 300E 2.6
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Discussion Starter #14
One flex disc was replaced at 136k, car has 216k right now. I do not know which one was replaced but both look to be in good condition.

Most likely I’ll go find a road force balancer to be sure it’s not the tires, but like I said, it was the same prior to the tire replacement.


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Discussion Starter #15
Any issues with wheel bearings, particularly the front?
No issues with any of the wheel bearings that I’m aware of that I can tell. No typical grinding/humming/vibrations typical of a bad bearing.


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If you have the ability, shift the front tires to the rear and visa versa. This might cure it. If it does, you have a balance issue but honestly, balance issues don't "care" about hot or cold so this is a longshot.

How about the struts/shocks. How much time do you have on them? A weak strut will exagerate the effect of a bent wheel rim or out of balance tire.
 

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1992 300E 2.6
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124 Posts
Discussion Starter #17
If you have the ability, shift the front tires to the rear and visa versa. This might cure it. If it does, you have a balance issue but honestly, balance issues don't "care" about hot or cold so this is a longshot.

How about the struts/shocks. How much time do you have on them? A weak strut will exagerate the effect of a bent wheel rim or out of balance tire.
So far as I know, they’re all original but ride fine and don’t make any typical symptoms of bad shocks.

It’s just weird that it stops and is very conditional.


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89 190E2.6- 5-speed Manual, 95 E320 Sportsline-sold, 2001 E320 4matic Wagon-sold
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The one thing involving the drive train that warms up after a few minutes of highway driving would be the transmission.
Could this be a torque converter or other transmission issue when cold? Was this already discussed?
 

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Couple of things:
  • can you isolate where the vibration comes from? Ex: right front wheel, left rear, engine area, etc?
  • if by "they are original" you mean your struts and shocks are 28 years old and have (fill in the blank) miles on them, then you might be very surprised at how well the car will perform with new ones.
 

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1992 300E 2.6
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Discussion Starter #20
Couple of things:
  • can you isolate where the vibration comes from? Ex: right front wheel, left rear, engine area, etc?
  • if by "they are original" you mean your struts and shocks are 28 years old and have (fill in the blank) miles on them, then you might be very surprised at how well the car will perform with new ones.
I’ll see what I can do, this one is pretty difficult to pinpoint since it doesn’t last long.

As far as shocks, I’m contemplating new ones just to do it-but the car handles and rides fairly well as is. The only thing that gets me is crosswinds on the highway-the car gets pushed about pretty well.

I know there’s a few brands of comfort-tuned shocks. Dunno if Bilstein, MB, or what would be the best ride.


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