1983 SC Overheat and now No Start

[ischmitz]

The whine of the CDI is a first good sign. It means the box is not completely dead and its DC/DC converter is working. Can you tell the pitch? It needs to be around 3.5kHz. If it is much higher it is a shorted box.

As you can tell a whine is not a 100% clean bill of health - there could still be a problem inside the CDI box. I recommend finding someone with another 6-pin CDI nearby for a quick swap-test:

Either you swap yours into the running car or get the good one - either way it is safe and won't cause any subsequent damage.

If problem doesn't follow your CDI box you should concentrate on the green trigger wire from the distributor to the . These have been known to go bad. It is a COAX cable and once the outer wire mesh shorts to the inner signal wire due to deterioration of the plastic insulation there is no spark.

Ingo

[1983Cabrio]

Hi - I just ordered and replaced my coil with a new one. I removed the BLACK coil (looks pretty original) and replaced it with a silver one made in Brazil (new) - and STILL NO SPARK. I tested the poles at the coil, and with the key on, the RED wire into the Bosch CDI is hot, the white out to the coil is not. So - no power to the coil. (Good earth on all) The CDI does whine when the key is on. What's next?

[1983Cabrio]

AAAAHHH yes, the Green wire to the distributor is very brittle from the heat. How do you get that stubborn plug out of the distributor?

[1983Cabrio]

...I guess my new coil was a bad choice huh?

[1983Cabrio]

What about the temperature switch? does that do anything?

[ischmitz]

A CDI doesn't supply permanent power to the coil so you cannot measure it the way you did. Once it whines you have confirmed it gets power. It can still have an internal issue or it doesnt receive a trigger impulse (green wire).

Try and find someone in your area with an SC and swap your box into that car. This is the only real test short of sending the CDI unit out for testing.

I would be suspicious about the green wire. If it is brittle chances are it has an internal short and that is what's causing your issue.

The temperature switch does nothing with regards to spark.

[theiceman]

Yeah the silver coil is nothing more than a paper weight, that's why I recommended the blaster coil. Probably as pointed out though the cdi is next thing to check.

[sf2oc911sc]

Same thing happened to me under the same circs too. Ended up replacing the CD box and was experiencing hot start probs so changed out the fuel accumulator and fuel filter while I was there. Runs great now.

[timmy2]

It is easy to check the green wire after removing it from the distributor (by removing the metal retaining clip first)...

Remove the 6 pin connector and see if the green wire and shield have proper continuity with an ohmmeter. Test them separately and then to each other. If the green wire is isolated from the shield and both have continuity overall the green wire is ok.

[1983Cabrio]

Thank you, I'll test the green trigger wire with my meter. Kinda sucks that it's a $79 wire!

[Vereeken]

Although I suspect a melted Green wire I would try to find an old working black coil.

The silvers ones can be DOA.

it happend to me. I could not get it to start with a silver bosch coil (brandnew delivered that day). Swapped in an old black one and presto.

It makes troubleshooting much more difficult. Bosch does not seem to care about QA.

Made in Brazil? Run.

[1983Cabrio]

So - update. The green wire has perfect continuity to the CDI plug. No cross talk, and good connection. CDI whines and is good. Next up is to switch out back to my old black coil and see if that works. I replaced the coil wire when I did the Brazil coil... if the coil doesn't work - I need to get a CD box, huh?

[1983Cabrio]

Put the black coil back in. Also replaced all of the spark plugs with Bosch Super Plus 7992. Still no pop.

[1983Cabrio]

I am CERTAIN that I did this during one of my tests. I could have blown both the CDI as well as both coils. Wicked learning curve.

[Vereeken]

Perhaps; but get a hold of a good secondhand black coil.

My way to troubleshooting these things is to go from cheap to expensive parts.

A black coil should cost you 25 dollar.

Do a search on how to test a coil with a multimeter. Mind you that will not help you with the Silver one as it can test out perfect.

Take a look at the ground strap under the car next to the transmission, just for good measure.

I agree with Tony. Even with bad compression you should be able to start.

So you are still looking for spark.

[boyt911sc]

1983cabrio,

Hook up an inductive timing light and find out if you are getting signal (sparks). If you don't have ignition sparks, no amount of perseverance and hard work could make your engine start or run. Focus on one subject at a time. You need 'ignition' first and foremost. You could not attain internal combustion without ignition sparks during compression. So something is causing your system to lose ignition sparks during cranking. Either component/s problem or wiring anomaly. If I were in your shoes, I'll try to find someone local with an SC car who would be willing to test your CIS components like CDI and coil.


I don't know how to test and evaluate a CDI aside from listening for the whining noise it makes when energized. So I used these known working CDI for my evaluation. There could be someone in your area that could help you test them. Post a 'Need Help' and if you could not find someone willing to help you, PM me and I'll test them for you. Keep us posted.

Tony

[1983Cabrio]

Thank you Tony - I just pulled the CDI and sent it out for a rebuild. worth $175 to me... when I get it back, I'll pop it in and see if I have spark. Yes, with so many options, it is hard to focus on one problem at a time... ug. I don't know anybody else with an SC in my area... Anyone?

[1983Cabrio]

Oh, in Woodland Hills, California

[1983Cabrio]

Originally Posted by theiceman

Yeah the silver coil is nothing more than a paper weight, that's why I recommended the blaster coil. Probably as pointed out though the cdi is next thing to check.

Thanks - If you have your model number that would be so great... I want to order a new coil....

[1983Cabrio]

HI Guys! I wanted to give you an update on the project! I FIXED IT! Turns out that yes, the heat from the engine melted the CDI. the C8 energy storage capacitor was failed open. (melted) - so I have a new Master Blaster coil as a spare, but the Black original coil is FINE! Green wire is FINE! And with an oil change (because of the heat) there were no metal fragments in the oil. A wicked catastrophe averted!!! I am SO RELIEVED!