Need help from ignition gurus

[jabar102]

Hello everyone! I've been through numerous threads on here related to ignition and I am still stumped. Car is a 1965 230 SL.

Here's the rundown: car was running fine. Take it into town to have lunch and wouldn't start afterwards. It cranks, starter works, but can't get anything to go. (got it to start one time and then it died). Had it trailered home.

Here's what I have done: seems like I have no spark at the plugs. Adjusted points, checked all leads. Nothing there, looks good. Checked coil, but here's where I am unsure: coil resistance seems in range. I have 12V when starting at the + side of the coil. I don't seem to have any voltage coming out of the HT side of the coil. I do get one spark when first turning the ignition, then nothing when cranking.

Tried the following: energized the coil directly from the battery, put a spark tester on the HT side, tapped the - side of the coil to ground. The spark I get is NOT on the spark tester, but on the - side when tapping the ground.

Does this indicate a short to ground somewhere else? Or is the coil bad? (coil is a "red coil" with a brand new 1.8 ohm ballast).

Any ideas on further troubleshooting?

Many thanks in advance (on this Thanksgiving day in the US!)

[roymil]

After the initial failure, the fact that you got it to start one time before it died again kind of says to me that you didn't have a hard failure in the ignition system.  Those don't usually get better.    It sounds more like a fuel delivery or mixture issue.   It's a classic scenario to for a well running car to be parked long enough for different bits of the engine to cool and cause incorrectly adjusted starting systems to skew enough to prevent starting.  I'd start by checking the cold start valve operation.

If you do still think its an ignition issue, then I didn't see that you checked out the points which must be the number one fail point in the ignition.

Good luck, and do checkout the starting aids section of this site which has excellent descriptions of all the starting systems and how to adjust them.

Otherwise have a great holiday!

[lpeterssen]

Hello Jabar:

Happy thanksgiving.  They way you described your ignition coil testing procedure was incorrect.

I subscribe the comments made by Roymil, that if the car ran perfectly and you parked it and had no success a time after to start it up again, it’s most probably not so bad.

The ignition coil operates this way:

1. Needs a positive feed on one side
2. The negative terminal is the trigger for spark.  Every time you connect to ground the coil charges, and every time you disconnect the ground circuit the coil is discharged through the central post which feeds the distributor cap.

Saying this, will let you to conclude that if you keep the ground connected all the time you will get no spark from it.  Precisely the function of the ignition points at the distributor shaft is to open and close that negative connection to the coil to let it discharge and charge the coil, getting the spark we need for the spark plugs on each cylinder.

So after checking that your coil is operational, go for the fuel delivery system and verify if your fuel pump beside the fuel tank is making noises (that will give you the indication that is spinning).  Then have someone to help you and while crank the engine touch with a positive cable the terminal of your CSV to make it open and have some fuel sprayed at your intake.

Another better option to discard that you have a fuel delivery problem, and not a spark related one is to buy at a car parts store, like Autozone, oRallyes or similar a can of SPRAY STARTER FLUID.  In that case have someone to crank the engine while you spray some STARTING FLUID at the intake butterfly (remove intake hose to Air filter housing).  If your engine try’s to start then your problem is fuel and not ignition related.

Have a happy weekend finding the root cause of your car illness.

Best regards
Leo Peterssen
Www.Wiredoktor.com

[Cees Klumper]

Maybe manually open the points, which if I understand others' posts correctly, should interrupt the '-' signal at the coil, and see if it is still grounded nevertheless, explaining why you have no spark. If yes, then either the '-' wire is grounding out somewhere, or I recall some earlier discussions about how a loose/compromised wire or contact inside the distributor can cause the short to ground.
If you have no spark, then I would fix that before spending any time on the fuel side of things.

[Benz Dr.]

Everything can look perfectly normal inside of the distributor but it will still not work. Any dirt or corrosion on the points will cause an interruption in the circuit and the coil will not fire. Dirty points are a common no start problem.

[jabar102]

Thank you all for taking the time to respond! Much appreciated.

Fuel pump is less than a year old and seems to be functioning as expected. Will check on the fuel delivery as suggested.

What still makes me think it is a spark related issue is when using a spark tester at the plugs, I see nothing. When I take the HT lead from the coil (normally leading to the distributor) and put it a few mm above the engine block and crank, I get no spark.

But from the answers above I think I understand that since the - side of the coil is connected to the distributor, if there is a grounding issue in the distributor, it could generate this situation. Will take the distributor out again and check all components.

Again, thanks for the advice.

[jabar102]

So it was indeed the distributor! I took it apart (at least the points and the contact plate), cleaned everything (lot of oil in there that shouldn't have been), cleaned the points, etc...

Started right up.

Upon further inspection of the points, they were quite pitted and will be replaced. Probably because the previous owner had a 0.9 ohm ballast ahead of the higher voltage "red coil", which requires a 1.8 ohm. Probably too hot of a spark deteriorating the points.

Thanks again for all the pointers. Learned a lot about the ignition system!

[Bshaunessy]

JABAR102
  Congrats at finding the no start gremlin.   Well sleuthed!  Now that you have it narrowed down to the distributor / points set up, i would recommend converting to a "123 ELECTRONIC DISTRIBUTOR" ….no more hassle cleaning/ replacing / re-setting points and condenser.
  They are European designed and made but have an American division that you can on line buy direct from.
   I initially converted my 1970 280 SL ( 30 min DIY job) and liked the ease of install and reliability so much i converted my 1957 190 SL and my 1975 450 SL. ( i have no association with 123 DISTRIBUTORS…..im just a satisfied user).
 

[franjo_66]

I totally endorse the recommendation for converting to the "123 ELECTRONIC DISTRIBUTOR". My 230SL has had this installed 10 years ago. Still running great with no problems or issues !

[ja17]

Try to use original Bosch brand ignition points. I noticed most after-market brand points do not last. One exception is Ikar ventilated points which seem to be fine. Also the metal terminal bolt which passes through the iron distributor body  and connects the ignition points and coil wire, should have a tiny insulating sleeve around it. Often times has degraded and fallen apart or missing all together.

[jabar102]

Thank you for the advice on the 123 distributor. I’ve definitely seen a lot of people refer to it in many threads I’ve browsed.

A bit of a neophyte question then: in addition to replacing points/condenser setup, does it also relieve you of setting the timing manually? Timing strobe and adjustment on this car is less than ideal given the location of timing marks, etc.

[ctaylor738]

I am also a big fan of the 123 distributor.

You will have to set the timing when you install the 123.  But you should not have to mess with it again, unlike points where the timing should be checked when they are replaced or adjusted.

Cheers,

CT

[Pinder]

I installed the 123 ignition with the blue tooth last year (maybe it was 2 years ago). Best choice I made on a 1970 280SL. It is simple to install and came with  a new bracket. It can pair with your iphone and you can try out different timing curves. its a really nice setup. My car runs so much smoother with it. Also i made a sligth modifcation to my throttle body so I could by pass the emission control relays which I was not 100% sure were working on my car. I think I did have it all working right but its unessary complexity. I can easily switch between using them or switching the vaccum line at the to the throttle body and running it as if it were a 1969 without emissions relays. I currently run it as a 1969. 

You will have to set the initial timing if you put this system in. I cant see how you wont do that. It is worth the investment. Just keep your old distrib.   I also replaced the coil to match.

Good luck.

[UJJ]

Hi Pinder
What coil did you install?
I also installed the 123 Ignition distributor, but I left the coil untouched. It is the red Bosch coil.
The car runs fine, however, you say that you matched the coil?

Thanks, Urban

[Pinder]

from 123 iginition, I ordered it with the coil. Which is item BOS-0221119021 Bosch Coil 1.9 ohm recommended for 4,6 and 8cyl applications, Bosch Red.

Hope that help. My old coil I bought new back in 2018. It would proably work with my old coil but I thought go new.

Hope that helps.

Pinder

[Pawel66]

Hi Pinder
What coil did you install?
I also installed the 123 Ignition distributor, but I left the coil untouched. It is the red Bosch coil.
The car runs fine, however, you say that you matched the coil?

Thanks, Urban

If memory serves me well, there is a minimum resistance requirement for 123, you may want to check if your coil is at or above that parameter.