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Hello all! We’ve got an 85 300D. A few months ago, out of the blue, the key wouldn’t turn. After looking online, I found that this is common on the older Mercedes. I got it to finally start and took it straight to the shop. They replaced the ignition cylinder. So now it has a new key for the ignition. It was fine for a few weeks but now it does it again from time to time. So far, I’m able to wiggle the key and force the wheel lock back and forth and it’ll start. It’s my girlfriends primary transportation. She doesn’t feel she can rely on it. It seems it’s not so much the ignition cylinder but the steering wheel lock. Could this be disabled? Anyone else go through this? Thanks!
 

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1985 300 TD 1981 300 SD
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The actual problem is likely to be the ignition lock sticking itself, any pressure on it from the steering wheel will make it feel like it's jammed. Try to pull move the wheel a bit left or right ( depending which way the wheel is turned) to take the pressure off of the lock pin and see if the key turns freely. If it works then you should plan on pulling the whole lock assembly for a tear down and clean, or leave the lock pin out when you reassemble.
There are plenty of threads here and on the 126 sub forum to help you .
 

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Discussion Starter #3
The actual problem is likely to be the ignition lock sticking itself, any pressure on it from the steering wheel will make it feel like it's jammed. Try to pull move the wheel a bit left or right ( depending which way the wheel is turned) to take the pressure off of the lock pin and see if the key turns freely. If it works then you should plan on pulling the whole lock assembly for a tear down and clean, or leave the lock pin out when you reassemble.
There are plenty of threads here and on the 126 sub forum to help you .
Thanks!
 

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1985 300 TD 1981 300 SD
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348 Posts
Something else, there are a number of videos on YT that will help you with your Benz, Pierre Hedary's is the first channel that comes to mind.
 

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1984 300D
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When it happened to me it turned out my Steering Colum Lock was broken internally.

There is sort of a bonus when you purchase a new Steering Colum Lock Assembly and that is you get a new Ignition Switch with it (it turned out there was a nearly burned off contact on the old Ignition switch) and you get a new Vacuum Valve.

The picture is of parts of the inside of the steering colum lock. Note there is a broken off shaft that would have gone down to the Ignition Switch and anther area where a detent ball was. It turned out my Key Lock Tumbler was still good and I reused it.
Others have had other parts of the Steering Colum Lock break inside. And it has similar symptoms to the bad Lock Tumbler issue.
Inside of Sterring Colum Lock broken 2019.jpg


If you remove the Steering Colum Lock Assembly you have to remover the Safety Belt Switch. If you can find any of those old cheap flat wire bobby pins you can slide them into where the red arrows point and depress the plastic hooks inside to slide the switch out. Before you do that you need to rotated the innards so that the little plunger on the Safety Belt Switch is depressed otherwise it won't slide out.
Or when I did mine I carefully sawed off the outer aluminum Safety Belt Switch retaining lip and freed it up that way but I knew I was going to replace Steering Colum Lock.
Steering Colum Lock Seat Belt Switch 2019 z.jpg


This is a pic of the Steering Colum Lock Assembly and I identified some of the components. In that area where it has the Lock Tumbler going there is a metal finger. Some have had that metal finger get broke or the 2 indentations that the back of the lock tumbler goes into become broken or elongated.
Steering Colum Locking Pin 2018.jpg
 
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