W123 ignition completely broken, what do? - PeachParts Mercedes-Benz Forum

dinman · #1 05-26-2018, 03:32 PM

So I started a thread a while back as to why my w123 would not start, out of nowhere.

After some help from you guys, I jumped the starter off and it fired up.

But I wanted to do some troubleshooting. So I tried jumping the NSS. no go. Wiggled the shifter around. No.

Tumbler was just replaced. So I figured no issues there.

But after turning the key a few times when testing my jump wire on the NSS, I noticed that the key was no longer going that extra bit to actually hit the starter. It was just stuck.

So I removed the tumbler, and proceeded to try and crank the car with a small screwdriver in the ignition.

Voila. It fired the starter off. So to recap- NSS plug was cleaned and reinstalled as usual, tumbler was removed, and starter fires from within the car when using a screwdriver.

Here's the big Problem- when I used the screwdriver to crank it, it "broke through".

What I mean is- the ignition now just spins and spins and spins freely. None of the electronics will turn off and the shut off valve is constantly pulling vacuum.

I disconnected the shut off valve vacuum, and the car is currently running.

I am scared that if I shut the car off with the emergency shut off, and then disconnect the battery, that I have absolutely have no way of turning the electronics back on until I replace the entire ignition assembly.

So that's my question- what do I need to do in order to remove the ignition for replacement, before shutting all electronics down.

I didn't even know the ignition could fail like this. It literally just spinning freely.

Any help would be greatly appreciated. Thanks

HarvAMG · #2 05-26-2018, 03:50 PM

Sounds like you broke something in the ignition. The screwdriver has too much torque and went too hard with it. My advice, drive the car somewhere where it can sit and you can work on it. Then shut off the car with the emergency shutoff. Then get to work pulling the ignition switch out. Just order the entire unit. It's not a tough job, I did mine in my driveway.

You need this:

Diesel911 · #3 05-26-2018, 10:30 PM

Ignition Switch not working due to problem inside of Steering Wheel Lock
removing ignition switch - PeachParts Mercedes ShopForum

Steering Wheel Lock Ignition switch removal
DIY Ignition Switch/Steering Lock R&R W124 - PeachParts Mercedes ShopForum

BillGrissom · #4 05-27-2018, 12:29 PM

Sounds like the problem is just in the ignition switch. That is a cheap part which attaches to the fwd side of the stalk w/ 3 screws (flat screwdriver). The problem is not much room to get a tool in there. Perhaps try a dollar store mini-ratchet tool.

In my 1984 300D, rotating the key would hang on something. It wasn't in the tumbler. I removed the flat steel plate from the stalk and found the spring detent had broken off and was jamming parts. I removed that. Don't have the detent, but the key has never rotated while driving (aka infamous GM switch problem). Wish I had left the steering lock out when I re-assembled since don't need that anti-theft.

dinman · #5 05-28-2018, 12:37 PM

Thanks guys, i ended up getting the whole ignition out. The ignition switch on the back side was loose, in fact one screw was backed all the way out and the other two close behind. I screwed it back together, and the ignition "feels" way better but it still doesn't hit that last detent to fire the starter. Also, no matter what, when i plug the ignition in, the radio fires up. But nothing else. Turning the key does nothing. My ignition had a ton of oil in it when i removed it and the little two pin connector on the ignition was missing. I'm guessing i just need a whole new ignition?

BillGrissom · #6 05-28-2018, 05:02 PM

Oil gets into the ignition switch from the vacuum switch that attaches to the side. That switches vacuum to the stop-valve on the rear of the injection pump. When the stop-valve's diaphragm tears, oil gets sucked up the vacuum tube to the switch, eventually dripping on your right foot (ugh). Install a tiny clear filter in that tube so you can monitor for oil before it gets everywhere, and know to change the stop-valve.