Intermittent complete power failure in 1967 230Sl

[David N Osborne]

Listmates —

I have a vexing problem with my 230SL.  Most of the time the car runs perfectly well but it will from time to time suddenly have complete interruption of power supply.  No ignition, no lights.  Battery and alternator are fine.  Radio will sometimes have power but even that will fail if I try to test lights or ignition.  No red ignition light in dash.  Then all power will miraculously return to normal and car will run fine before, at some point, going completely dead again after turning off ignition.  Logic suggests some loose connection but car doesn’t fail while driving and with normal road vibration so loose connection seems unlikely.  Have replaced the voltage regulator with the recommended solid state version.  Hasn’t solved the problem.
Any ideas what needs to be looked at?
Thanks in advance for any input.  Much appreciated.
David

[WRe]

Hi,
did you check your ground cables and connections to and at ignition switch or the switch itself?
...WRe

[lpeterssen]

Dear friends

I Agree with Member called WRE , the culprit is the ignition tumbler switch or main ground post on the right side behind the instrument cluster is loose.

Remove instrument round dial on the right side (speedometer) since you need to take it out to check the connections behind the ignition tumbler switch, and at the same time, visual inspect how tight are the grounds terminals there.  Take the chance to disconnect those grounds terminals by removing  the hex 10 nut which holds them, sand the surface where the grounds are fixed until you have shiny metal surface. Reconnects them after you sand and polish each “O” shaped connector as well.  You may use conductive grease in that post if wanted.  (Carbon grease, look on Amazon, is not Dielectric grease, because that would cause the opposite effect, less electrical conductivity)

Grit 240 is great for polishing the post terminals.

Replace the ignition tumbler switch for a brand new one if you find that grounds terminals were well connected, as it is the most probable culprit .

Nevertheless, as explained before, is a good practice to polish those ground connections to have better electrical performance in all the car accessories.

Best regards
L.peterssen

[lpeterssen]

Here the link for the conductive grease at AMAZON

MG Chemicals - 846-80G Carbon Conductive Grease, 80g Tube
by Amazon.com
Learn more: https://www.amazon.com/dp/B005T8ROWA/ref=cm_sw_em_r_mt_dp_V9J48MY64ZRH29Y0PTDA?_encoding=UTF8&psc=1

[lpeterssen]

Indicate if your cabin lights are still powered or lit when this failure occurs

[David N Osborne]

Excellent.  Will do and will then report.

Thanks everyone!!

David

[dirkbalter]

If it is the  ignition tumbler switch, as suggested above, these are not easy to remove. They are crimped in three places along the OD. The crimps tend to get loose over time (50+ years). The cap separates from the base a bit and the contacts no longer engage. It may be wise to get a new one but they are not difficult to restore / re-crimp, assuming all the internal parts are ok. I did mine and my neighbors. At the time they were NLA from Mercedes. You would have to buy an aftermarket one SLS or Buds or so.
If needed, I have a series of pictures as well as repair instructions from ze German SL side.   

[Larry & Norma]

Just in case you have not tried the obvious, I had a similar problem always let me down at the wrong time like preparing to leave a ferry! Total power loss. Turned out to be nothing more complicated than
the positive cable had come loose in the battery connector, the connector was tight to the battery but the cable had come loose within the connector. Replaced the connector no further problem.

[Tyler S]

Power goes to the headlight switch before it travels to the ignition switch. Check B+ connections at the headlight switch, alternator B+ post, starter, and as stated above the battery connection.

[waltklatt]

David,
Check the cable connection terminal at the bottom of the oil pan on Passenger side.  You will see a terminal connection there.  remove and clean all connections and put back together.
Had a customers car that was faulty at that point.
Walter