Ignition switch/tumbler removal stalemate on a 1967 250SL

[AndyM1983]

Hi All

I have an ignition switch problem, were essentially when the car is started and key returned to the run position, the engine stops. Having checked/replaced coil, ballast resistor and gone back and forth testing various bits and bobs, the issue seems to be somewhere in the ignition switch. When i start the car and then carefully allow the key to move from the crank position back towards the run position, i can hear the starter motor switch off, but just when the key is at the run position and i take my fingers off the key, it cuts out. So thats the issue and so I have begun my odyssey of trying to replace the ignition switch. I have scoured the forums of this site and have followed as many instructions but seem to have fallen at the final hurdle and would be very grateful for any advice.
It's a left hand drive 1967 250SL, so i have removed the tach, the central instrument cluster and speedometer, I have removed the bolts holding the steering column strap which has intoduced some play into the steering column although it hasnt exactly dropped. I have removed the screw/bolt from the C clamp that holds the steering lock mechanism (attached to the tumbler) to the steering lock shaft attached to the steering column and removed the decorative chrome ring that fits around the tumbler on the dashboard side. I have moved the key to position 1 in the ignition to disengage the steering lock and there is now significant play in tumbler/ignition switch, but not enough to wiggle the unit out of the dashboard, seemingly because the chrome sleeve that sits around the barrel can not be manouvered out of the hole on the dashboard. So I am left in the situation shown in the photos below. I have tried detaching the ignition switch and leaving the tumbler mechnism in place but i just cant get to one of the screws without taking the whole lot out. Any advice or help would be much appreciated.

Cheers

[WRe]

Hi,
there could be a locking pin underneath the gripper clamp.
Did you read this: https://www.sl113.org/forums/index.php?topic=27823.0.
...WRe

[lpeterssen]

Dear Andy

You do not need to take out so many things to change the ignition switch tumbler.  Your problem is not on the mechanical /lock/ key part of the lock assembly. The problem resides only in the tumbler switch which can be taken out just by removing 3 flat drive screws which are on the back of the tumbler. Use a short flat drive screwdriver for that and you are done. Then take out the cables attached to each of the terminals and replace it.  The other terminal (cables) screws are Phillips head sometimes. Consult the mercedes pagoda wiring diagram to know which cables goes to what terminal.

Regards
L.peterssen

[AndyM1983]

Thanks both, I really appreciate the advice.

WRe, I did look at those procedures, but unfortunately I think my car is an old style 250SL (230SL style) as opposed to the 280SL so a different locking mechnism i believe.

L.peterssen, i managed to get one of those screws out but it is really tight around the back of the ignition switch and I was really struggling to get to the 2 of the 3 screws and hence was thinking about trying to remove the whole lot to make the job a bit easier (clearly the only bit that would be easier would be removing the ignition switch as removing the whole lot has been a head scratcher!). I will have another crack at the ignition switch screws.

Any further advice would be much appreciated just in case my sausage fingers fail to get the ignition switch out in the current position.

Thanks again all

Andy

[lpeterssen]

Dear Andy

Try something like this ultra thin screwdrivers from NEIKO

Neiko 01323A Ultra Low Profile Offset Screwdriver Set, 5Piece | Heavy Duty S2 Steel Construction https://www.amazon.com/dp/B07GNPRRVZ/ref=cm_sw_r_cp_tai_GMxgFbMN6CPMV

apply some wD40 on the screw heads to reduce the effort needed to take them out.

Best regards
Leonardo Peterssen

[AndyM1983]

Thanks v much for the advice. I have managed to remove the ignition switch. Hopefully a replacement will do the trick. Putting it all back together again and that screw round the back could be interesting!

[lpeterssen]

Andy:

Good to know you had success on that matter.

For sure it will work fine once the new ignition tumbler is installed

Best Regards
Leonardo Peterssen

[lpeterssen]

Andy:

If that doesn’t make the trick you will have to replace the red/black cable that goes from your ignition tumbler to the main fuse box Input port fuse #2, (that is the 15/54 feed wire) size 2.5mm2 which equals to AWG-14.  Also to be on the safe side change cable red/black going from fuse#2 input directly to ignition coil resistance (input side) size 1.5 mm2 == AWG 16.

On some pagodas the first cable from tumbler to fuse box input port 15/54 is changed from a single cable size 2.5 mm2 to two cables in size 1.5 mm2; having a total section of 3mm2.

[ja17]

There are two main mounting bolts near the instruments which hold the steering column tightly to the dash. Loosening these will allow the steering column to move slightly downward. Now if you turn the key to the first position, you can depress the small lock pin. Once the lock pin is depressed the steering lock and key assembly can be rotated for easier access or completely removed without removing the entire steering column.

[Charles 230SL]

Andy, fwiw, I replaced the ignition switch on my '64 230sl about 5 yrs ago without removing the steering column and the tool shown below really came in handy.

Once I installed the new (NOS) switch on the back of the lock assembly, I removed the wires one-at-a-time from the old ignition switch and reconnected each one to it's corresponding terminal on the new switch. Took some patience,,

[AndyM1983]

Thanks all, I am away at the moment, but will hope to have a chance to fit the new switch soon and will report back if successful. One thing i did notice as i was ferreting around under the dash was this wiring component (photo below) with what appears to be a a very degreaded/melted wire going into it. I am struggling to work out what it is though and whether it could be related to the starter issue. Does anyone know what this is? It is under the dash on the drivers side.

[cfm65@me.com]

Hi Andy,
Your photo seems to be of the back of the fuse box. If so, see if you can determine to which fuse the burnt wire goes. As you can see there are a few red wires coming to and from the fuse box. See if you can find a tracer colour on the remains of the burnt wire and where it comes from.
It is of course possible that the burnt wire has already been replaced and the charred remains were simply left behind because of the difficulty removing one wire, if the loom is still in the car.
Regards
Chris
Cape Town

[AndyM1983]

Thanks Chris, that is what it is and now you have said it seems obvious! I will investigate this wire further!

Thanks

Andy

[lpeterssen]

Dear Andy

That melted wire is for your ignition coil resistance feed wire.  As that is a not fuse protected power line taken from the port.no2 on your fuse box responsible for feeding all circuits that are active with the ignition on the acc on position.  I would not be so calm, that is not good at all.  Disconnect battery immediately, and proceed to trace the cause of the failure. At some point a bad insulation on that cable made direct contact to ground, and that caused the melted wire. As this is a not fused wire the damage is not only there but on cables around it which were exposed to high heat.

Disassemble the main fuse box by taking from the engine firewall side two 8 mm bolts in some cars or some Phillips screws on others, so that you can drop the fuse box inside the cabin and make a further assessment of damage caused.

The melted wire appear to be RED/BLACK and It is a thick wire around 2.5 mm.  So I am pretty sure that it is main T15/54 feed wire coming from ignition tumbler.  And.... that melted wire for sure was the responsible of damaging your ignition switch tumbler.  Check that I am correct or not by doing a continuity test between ignition tumbler switch port 15/54 and that melted wire.

If you need further assistance write me per PERSONAL MESSAGE and I will help you with joy.

But do not use more the car until we are clear on how damaged is the wiring harness. It could catch fire.

Best regards
L.peterssen