No Current to Distributor & No Spark to Plugs.

[Mike K]

A few weeks ago I posted a thread regarding my 1971 280SL Pagoda and problems I was encountering with a rusting fuel tank: http://www.sl113.org/forums/index.php?topic=19421.0

Thanks to great input from this Forum, I temporarily sorted out the problem by flushing out the fuel tank, new filter and unblocking the passage into the flower pot. The car ran perfectly while I waited for my new fuel tank to arrive. BYTW I had also removed and checked the fuel pump which my electrician said was hanging on by a thread and beyond repair, so I ordered a new fuel pump as well.

To cut a long story short, yesterday the new fuel tank and new fuel pump arrived and I replaced both. This was relatively straight forward and job done in about 3 hours.
Prior to starting the car I bled the system by  loosening the injectors until I could see fuel flowing through.

Now onto the new problem: in turning the ignition over 6 or 7 times and trying to start the car, and as it was about to start I noticed a bit of smoke coming from under the battery-side of the car. The engine was turning over but not starting. I figured there was no charge flowing through to the spark plugs.

Following Haynes Manual pg.98, in sequence, I ran a check with spark plugs removed and held against engine block, no spark, then ran a check with centre HT lead from distributor against engine block again no sparks, the coil is new, l did a voltage check on the coil, again no current.

I figured that the problem therefore has to be before the coil.

So I then followed the wire from the distributor/condenser down to under the battery compartment, and crawled underneath the car and found the switch gear.
On closer inspection there are 3 or 4 wires coming out of the switch gear all intertwined and covered in grease and muck.
On cleaning these wires they look burnt/shorted, the smoke I saw must have been from here, maybe burning grease and crud?
One of these wires goes to the distributor.

Is it possible that the switch gear is cooked and hence no current to distributor?
Would a burnt out switch gear stop the current from flowing to the distributor and hence no start- I have read here that the car will still start but die after a few seconds.
Possibly the condenser on the distributor is also cooked?

What should be my next step?
Try and repair the wires and try again, or?

I’m really stuck now!
Input and advice will be greatly appreciated.

Many thanks,
Mike

 

[mdsalemi]

Mike,

Just a guess, but it sounds like your Bosch electronic unit--which I believe was on 1970/71 models--may have fried.

Your best solution would not be to replace this--probably very costly if you could find one, but to replace it with something like a Pertronix (or HotSpark or Crane or any number of others) or if you are so inclined, a 123 unit.  This will simplify things quite a bit.

Others will have to weigh in here on how best to wire this up with the later distributors.  I have the cast iron -050 and you probably have an aluminum bodied unit which is a bit different.  The wiring will be simplified over what you have.

[Cees Klumper]

I'm with Michael on the diagnosis (in fact when I read about the smoke from underneath the battery the first thing that came to my mind was that the old switchgear must have died) and wil put in a good word for the 123 electronic ignition-complete-with-distributor, as it will address any possible issues with your old distributor and compatibility of that with any other electronic solution. There's lots of information on modern ignitions on the site and a special article I believe in a Pagoda Notes issue on the 123.

Good luck with this new issue and if it's any consolation, once sorted, these cars stay sorted for a long period of time, so there is light at the end of the tunnel!

[mdsalemi]

Mike K--

I should have been a bit more clear; the 123 is a complete, new "distributor and electronic ignition system" that has very favorable reviews here.  Somewhere in the USD $500 range, approximately.

The Crane/Pertronix/HotSpark etc. solutions are add-ins to your existing distributor and coil (though some like a different coil) and in some cases, your ballast resistor too. Give or take, about $100.

However--as a point of advice it pays to be real sure you don't have any issues with your distributor before you start. If you have worn bushings, play in the shaft, or any number of other issues internal to a distributor, best to have it rebuilt before you go installing an add-on.

[Mike K]

Michael and Cees- Thank you very much for your replies, greatly appreciated. It sounds like it's best to replace the current system with a 123 system.
I've already started doing some research into this. At approx. EUR300- the cost for the 123 system is not excessive, I just need to understand how to bypass the existing set up and install the 123.

I'm sure I'll have many more questions in the next couple of days, please bear with me.

Many thanks and best,
Mike

[Flyair]

Mike,
the Dutch producer of 123 is also able to advise on local installation shops who will do it correctly.

http://www.123ignition.nl/id/25.html

most of the info is here
http://www.123ignition.nl/downloads/

the closest reseller to you would be probably:
PRESTIGE GARAGE
Jean-Luc et Nanda
1330 ch. de Vosgelade
06140 Vence
tel: +33 (0)493581187
fax: +33 (0)493581177
prestigegarage@bbox.fr
www.prestigegaragevence.com

[Mike K]

Flyair- Thank you very much for your reply and info. I've made contact with Prestige Garage they're about an hour away from me.
I'll have the car delivered to them next week to fit and tune the 123 system.

Thanks Michael and Cees as well for your input, very much appreciated.

Best,
Mike

[Flyair]

Mike,

Good luck. Please let us know once you get that installed about the result and your impressions.

I am myself split about fighting to restore the original set up or rather going for something like 123. In my car, which is among the last ones producers in Feb 1971, the ignition is a kind of basic system with two adds-on, one acting at the start and another one supposedly keying in after the engine gets around 2400 revs. The previous owner, probably fed up with this complicated and delicate system, had installed a version that my mechanic dates at being installed in 1969 cars. So I am still hesitating, as getting it to 1971 set up would be even more costly than getting a new and dedicated 123. 

[Peter van Es]

And check our own technical manual: http://www.sl113.org/wiki/Electrical/123Ignition

And search the forums… there are many, many reports on it.

[ja17]

Yes, Stan, the original components for the factory electronic ignition are much more costly than the 123 system.  The main electronic control box is the same as the MB 6cyl sedans of the era. So some good used boxes may be available. However, I believe that RPM relay is unique to the SL. The sedan RPM relay has a different range.

[garymand]

Nice info on the 123.  Is the 10mm spring standard on all the models, 230, 250, 280?  I have never noticed a 10mm spring on my 250 or 280 distributors.  It might stay behind when you pull the disty?  Or more probable: sitting in someone's Extra parts bin? 

I'm guessing it minimizes backlash in the disty drive gear down below?

[Jonny B]

Under the "General Discussion" forum, check the sticky for Pagoda Notes, Issue Volume 3 No. 4 has a detailed article about the 123 installation.

[Mike K]

Update on the problem:
I dropped the car at Prestige Garage in Vence outside of Nice yesterday to have the 123 Ignition System fitted. They called me later in the afternoon to say the car was ready and I picked it up this morning. As suspected, it turns out that the Electrical Switch gear was totally cooked.

Jean-Luc who owns the garage said to me it's a no brainer, he fits the 123 system to all the classic cars that he services, including Mercedes, Ferrraris, Jaguars, Aston Martins etc.

The car started right away at the garage and I also immediately noticed that she was idling less roughly. I decided to give it a good test run, so instead of the taking the motorway back home, I took the scenic route through the backroads, mountain passes and forests, about 220kms in total. What an amazing difference in performance! I'm really pleased with the outcome.
Overall a fairly expensive month, new fuel tank (thankfully paid for by the seller), new fuel pump, new ignition system and coil. In the long run it's all worth it for peace of mind.

Thanks to everyone who responded to this thread and for the invaluable advice, all greatly appreciated! This just reconfirms what an amazing resource this Group is.

Best wishes for the Festive Season.