Author Topic: Quick symptoms check please - ignition switch? Which one for 280 SL? SOLVED  (Read 2087 times)

Cees Klumper

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Yesterday I was going for a short-ish drive (about 7 miles each way) to put fresh gas into my Pagoda that had sat idle for 1.5 years, with gas stabilizer in its tank. The car ran great and strong. Then, on the way back from the gas station, after about 10 miles total driving, the engine died very suddenly, as if I turned the key off. It stayed off for about 2 seconds, then started again as if nothing had happened. About 2 miles later it happened again, this time it did not restart and after pulling over I could not start it back up either. The starter did its best, but nothing. After I let it sit for maybe 2-3 minutes, it started up straight away as if nothing had happened, and I was able to ride the remaining mile or so home without a hitch.
A few years back, my ignition switch started to act up, and starting became more and more 'hit and miss', until it would no longer start the car at all. I hotwired a starting button as a temporary solution.
So now my theory is that the switch is failing further and now the normal 'position 2' that activates the ignition system,  fuel pump etc, is also on its way out. My issue yesterday could be fuel related, but it was so abrupt that I most suspect an electrical issue. It could also be a fuse that isn't making good contact so I will clean those up as well, but I would like your opinion on these symptoms. And as I need to replace my ignition switch anyway, I started looking for a  new one.
There seem to be two types offered for the 1969 280 SL: one with screw on terminals (€280) and one for a multi-prong connector (€70) that purports to work for all W113. Does Anyone know which type I should order? I know I need to disassemble the dash to get to it so will find out soon enough, but was just wondering if I can order one or the other safely now already.

UPDATE - last night I installed the new switch. That was an involved job, all gauges had to be removed. Anyway, because of the new switch I can now start the car normally again, whuch is nice, however on a test drive this morning the car stalled once again, proving the switch was not the culprit. I then swapped the coil, but that too made no difference. Still erratic stalling once the engine warmed up. Finally I was able to replicate the problem by manipulating the thin wires going from the coil to the 123 distributor when the engine was running. On closer inspection, I saw the negative wire's spade terminal was not crimped on properly and was a bit loose. Replaced that connection, and now no more stalling. I knew it had to be in the ignition circuit, and am very happy I was able to track down the cause.
« Last Edit: July 28, 2019, 20:17:21 by Cees Klumper »
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

Benz Dr.

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You should get the switch with plug on terminals.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

Cees Klumper

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Thanks Dan, I took a leap of faith this morning and ordered that one, it's on its way from Germany. Sure hope that addresses this issue, nothing worse than a mystery fault that can leave you stranded at any moment, anywhere!
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

stickandrudderman

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A simple test light at the ignition coil will tell you whether the ignition switch is at fault or not.
If your ignition is "on" but your test light doesn't illuminate when connected to the "+" at the coil then your switch or wiring is faulty.

Cees Klumper

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Thanks Stick, very practical suggestion. After replacing the switch, I will wire the test light into the cabin so I can see if, if it happens again, the light indeed goes off in tandem. At least it will rule out other possible causes.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

Cees Klumper

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UPDATE - last night I installed the new switch. That was an involved job, all gauges had to be removed. Anyway, because of the new switch I can now start the car normally again, whuch is nice, however on a test drive this morning the car stalled once again, proving the switch was not the culprit. I then swapped the coil, but that too made no difference. Still erratic stalling once the engine warmed up. Finally I was able to replicate the problem by manipulating the thin wires going from the coil to the 123 distributor when the engine was running. On closer inspection, I saw the negative wire's spade terminal was not crimped on properly and was a bit loose. Replaced that connection, and now no more stalling. I knew it had to be in the ignition circuit, and am very happy I was able to track down the cause.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II

teahead

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Awesome!

Seriously thinking of going 123 ignition too!
1970 280SL auto, AC - aka "Edelweiss"

Cees Klumper

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Thanks Rob. The 123 ignition is a worthwhile improvement over the original distributor. When I installed mine years ago,  I could tell the engine runs smoother. Despite me having already rebuilt my original distributor with new bearings, springs etc. Also no more points means less to go out of tune or wear out (points gap, dwell). The poor crimp connection on the negative wire to the distributor was my own doing. I am still learning.
Went for a 20 mile tour around our countryside here in France, top-down, and the drive was glorious.
Cees Klumper
1969 Mercedes 280 SL automatic
1968 Ford Mustang 302 V8
1961 Alfa Romeo Giulietta Sprint Coupe 1600
1962 FIAT 1500S OSCA convertible
1972 Lancia Fulvia Coupe 1.3
1983 Porsche 944 2.5
1990 Ford Bronco II