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1990 560SEL
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314 Posts
Discussion Starter #1
So I've got a 1990 560SEL with just 104,000km ( 65,000 miles or so ) and cosmetically it almost looks like new

DSC_4042.JPG (image)

however, while it looks like it rolled off the assembly line a short while ago, it doesn't really run like it. I have the rough idle issue, so I'm sure someone can link a good article on how to solve it, however perhaps my problem is a little more complex. When I rev the engine, even up to 2000rpm it's better, but still not quite smooth, it's not shaking dramatically and you don't notice it much while driving, but it's there when parked. It will also idle very roughly for about two seconds when first starting the car, after that it goes away. It's when the engine warms up that the rough idle gets worse again. I've tried two bottles of techron as I've heard a few people suggest that. It may have made a difference, but hasn't been an outright solution. The rough idle is sometimes embarrassing, especially when the car looks like it should run perfectly.

The other annoying issue I have is with squeaking and creaking in the interior. It drives me up the wall. Not only do I hear it when I drive over a rough patch of road, but when ever the car changes direction, accelerates, brakes etc... I've tried silicone in a few panel gaps, but have many people had this issue?

anyway, I'd like to have my car running as it should. I had the 96,000km service performed last year by the book and just recently had the 108,000km service by the book as well. The problem hasn't changed with either services.
 

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CH4S Admin , Outstanding Contributor
1985 500SEC, 1991 190E 2.6.
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40,108 Posts
Have you tried a forum search? The archive has a wealth of information.

Welcome, to take advantage of all the forum features, please re visit the 'Welcome to the Forum' tutorial sticky on top of the W126 page, as well as the two DIY stickies.
It will show how to search the forum (3 words min.), and has a link to the Russian MB site where you can run a VIN#.
Cheers
 

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Registered
1987 420SEL, 1976 240D, 1997 LR DISCO SE, 2006 Triumph Bonneville America
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68 Posts
May I suggest replacing the spark plug wires? This cured a rough idle issue I had with my 420... old wires arc'ing out everywhere. My $.02.
Cheers
 

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Premium Member
1990 SEC
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4,137 Posts
Congratulations on your purchase! :)

I'm sure you'll get lots of great miles out of the car once you've sorted the niggles.

Your car may not have a lot of miles on it, but it is getting close to 20 years old an some stuff just ages, whether it is used or not.

Rough or high idle can have a lot of causes. Some are easy and inexpensive to fix, other causes can be more expensive. Start by going over your ignition components (plugs, cap, rotor, wires) and chase down vacuum leaks. For further tips do searches on this site.

You may want to have the condition of you timing chain and guides checked out. These are interference engines, which means that if the timing chain skips a tooth on the sprocket, the piston will hit the valves and you'll have a $5,000 + bill for an engine rebuild. The chain itself is not the weakest link, it is usually the guides that will break. This is not just a mileage issue, age will dry out the guides causing them to become brittle.

As for the interior, do a Leatherique rejuvenator treatment of all the seats and something like 303 or Griot's rubber and vinyl conditioner on the vinyl and plastic parts (no Armorall, ever....). Once you've gone over all the surfaces, I'm sure you'll have a better idea which panel/part is loose and causing the rattle that drives you up the wall.
 

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W126 420SE & W126 300SE
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389 Posts
I had a noisy interior when I bought the car as well. I found it was the bottom of the door rubbing against the kick plate. So I just put some grease on the very bottom lip of the door panel and it sorted it out totally. The way to test is to open the door while the car is just rolling at low speed and if it stops making the noise you know what it is!

Good luck

Norm
 

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500E, E320, 190E, E55
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1,006 Posts
Good advice from axel wulff. thoroghly inspect ALL ignition components. 8 out of 10 times poor or uneven idling is due to worn ignition components.
 

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1990 560SEL
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314 Posts
Discussion Starter #8 (Edited)
Thanks all for the advice...

I've actually already had the timing chain and rails done. About 1000km ago I went to start my car and heard a terrible rattling sound. I thought surely it can't be the timing chain as it shouldn't need attention until 160,000km. I had to the car towed to the dealership as a precaution and it turned out the tensioner had gone and the chain was just slapping around. Had I tried to drive the car to the dealership I would have never made it...

I'll have a look at my ignition components and such, I should also have a look at the vacuum lines.

As for the creaking I'll take a closer look at the doors. I also hear it in the sunvisors. I don't want to have any visible felt but I'll try the other ideas including leatherique and such.
 

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Registered
500E, E320, 190E, E55
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1,006 Posts
seatbelt receivers are also a very common source of annoying creaks both on 124 and 126 chassis.
 

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Registered
1990 560SEL
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314 Posts
Discussion Starter #10
I tried some silicone around the bottom of the doors and the door sills and it made a huge difference. It's still not completely gone but much improved. The front passenger's door seems to be the source of most of the squeaks. I'll give the seatbelt receivers a try as well.
 
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