Smokin' hot ballast resistor

[Laldog]

Still sorting through the various loose wire, solenoid connections, etc related to a bogus ignition switch.

Newest problem is my ballast resistor is heating up to the point where it is smoking, and this after only 30 seconds or so of run time.

I tried a second ballast resistor and experienced the same red-hot results.

Any clues what may be the cause?

Also, does the igntion coil function only to start the car, or would a sub-par coil result in a very rough engine??

Is the coil a black and white either it works or it doesn't type of apparatus, or will it decline over time (like my backhand, jump shot and electrical skills?)

 

[MMercury]

Newest problem is my ballast resistor is heating up to the point where it is smoking, and this after only 30 seconds or so of run time.

I tried a second ballast resistor and experienced the same red-hot results.

Any clues what may be the cause?

The stock ballast resistor is made of ceramic/porcelain material capable of withstanding the heat created by the resistor material, which in this case is probably a wire. It is normal for it to heat up.

There is a vast amount of information posted regarding standard 12V ignition coils, including how they can be tested by the use of an ohmmeter. http://www.international-auto.com/a...m/alfa-romeo-how-to-test-an-ignition-coil.cfm

Most (but not all) 12V coils will work with any well tuned low compression street engine. Firing many cylinders at sustained high rpm tests the limits of many standard generic coils. As with most things, better coils are separated from their marginal counterparts by construction, materials, and design including windings. This is why some coils may continue to function adequately when other parts of the electrical system are compromised by a weak battery, deficient wiring, etc.

Coils typically fail when they are mistreated (dropping and heating) causing a break in the internal wiring or insulation material. They are often (but not always) encased in oil. Oil leakage may lead to an overheated coil and failure. Carbon tracking on, or near, the terminals, can lead to failure or suggests failure is likely. Extremely large spark plug gaps with high compression, substandard ignition leads or questionable cap and rotor equipment may exceed the limits of some coils. However, even the best coils will not function properly when other ignition and electrical components are in very bad shape.

http://www.youtube.com/watch?v=rJYJ3KvPhhY

http://www.youtube.com/watch?v=eKWsI2vNxPs&feature=relmfu

http://www.hotrod.com/techarticles/ignition_coil_tech/index.html

http://mgaguru.com/mgtech/ignition/ig108.htm

 

[61porsche]

Check you're running voltage to the resistor; should be about 13.5 v +-. If you're voltage regulator is wacky it could be putting out too much voltage and causing the resistor to be overloaded.

If you're putting out too much voltage a lot of things can go wrong besides that resistor.

 

[jmackro]

Check you're running voltage to the resistor; should be about 13.5 v +-. If you're voltage regulator is wacky it could be putting out too much voltage and causing the resistor to be overloaded.

If you're putting out too much voltage a lot of things can go wrong besides that resistor.

I agree with the above statements, but doubt that excess voltage is the issue. As 61porsche writes, if the voltage were that high, a LOT of accessories would be smoking. From experience, I can report that the load shedding relay, tach, and clock will fail if the voltage regulator allows the alternator output to rise into the upper teens.

My guess would be that either the coil has an internal short, resulting in too little resistance. Or something is mis-wired - e.g., the ballast resistor is connected to the points side of the coil, so it goes straight to ground when the points are closed.

does the igntion coil function only to start the car, or would a sub-par coil result in a very rough engine??

The coil is needed both for starting and running. The resistor is bypassed during starting, but is in the circuit while the engine is running. Are you saying that the car does start and run, but runs roughly?

Is the coil a black and white either it works or it doesn't type of apparatus, or will it decline over time

A coil can fail in any number of ways - it isn't "black or white".

I'd start by measuring the coil resistance with all wires to the coil disconnected as per the webpage that MMercury referenced. I'd also check that the coil is wired properly: "+" side to the resistor, "-" side to the points.

 

[Laldog]

Thanks for the reply

If it wasn't pouring rain, I'd be checking now.

It gives me a few good places to start.

I'm a little puzzled. I thought I read in previous posts that the Ballast resistor could be wired either way, more or less that it didn't have a positive and negative side.

In any case, I'm suspecting it's my coil, and seeing that the 2 I've used are pretty old- and ratty looking, it's time for a nre one.

Thanks again.

 

[jmackro]

I'm a little puzzled. I thought I read in previous posts that the Ballast resistor could be wired either way, more or less that it didn't have a positive and negative side.

Right, the resistor doesn't have a positive or negative orientation - you can swap its leads with no issues. But a coil definitely has positive - negative orientation. The resistor needs to go to the "+" side of the coil (might be labeled "16" on a German coil). And the lead from the distributor needs to go to the "-" side of the coil (might be labeled "1"). There will be a couple of other wires connected to the coil - there's a lead from the starter that bypasses the resistor during starter to the "+", and one from the tach to the "-".

 

[Tierfreund]

If it wasn't pouring rain, I'd be checking now.

Please don´t tel us your coupe is standing outside in the rain...

 

[teahead]

My resistor fell apart. Can I just use ANY universal one?

The OEM one is $70! This is just temporary anyways until I drop in my 3.5L.

Can someone check the resistance of their's?

Autozone sells this one for $11.00 that has .8Ohms resistance.


http://www.autozone.com/batteries-s...last-resistor/msd-ballast-resistor/139539_0_0

 

[Stevehose]

Your existing one should say the Ohm rating on it, needs to be matched with the coil. If it's .8 ohm then yes the AZ one will work.

 

[61porsche]

bad ground. loose connection.

 

[teahead]

Can't find the ohm markings, but the old one measured 1.4

 

[Wladek]

Take a good look at marked areas, treat them with wire brush - they should show up. In mine for the first i also thought that there is nothing.

 

[jmackro]

My resistor fell apart.

The 1.4 ohms that your meter shows may not reflect the resistance when it was new. Given how messed-up that thing looks, it may well have had less resistance (e.g., been closer to .8 ohm) when new. It is also difficult to measure low resistances with a meter. Heck, the oxidation on the connections is probably adding a few tenths to your reading. So if you can read anything on the bracket, that would be a better indication than the meter's reading.

Autozone sells this one for $11.00 that has .8Ohms resistance.

To save $(70 - 11), I'd probably give the AZ resistor a try. What's the worst thing that could happen? OK, you might melt your wiring harness, set your car on fire, and burn down your garage, but hey, you've saved $59.

 

[sfdon]

Remove the red/black wire from the starter

 

[teahead]

Remove the red/black wire from the starter

Don't understand. Car won't start without that connected

 

[sfdon]

You tested that?

 

[teahead]

If I remove that wire, turning the ignition key will then do nothing. Not even a crank of the engine

 

[sfdon]

The black/red wire ?
At 12:00 position?
The wire that delivers voltage to the coil when you crank?
http://www.e9coupe.com/tech/autobooks/appendix/autobooks_manual_154.htm

 

[teahead]

The black/red wire ?
At 12:00 position?
The wire that delivers voltage to the coil when you crank?
http://www.e9coupe.com/tech/autobooks/appendix/autobooks_manual_154.htm

Oh sorry, someone replaced that wire on my car w/a green wire. I thought you were referring to the black wire going from ignition to the starter.

Interestingly enough, that black/red wire you're referring to (from starter to coil) has only .5v coming out of w/the ignition in the run position. So instead of using that wire from the starter, I used a jumper wire from one of the carb choke wires to get 12v to the coil.

And I still can't get spark coming out of the coil!!! Must have a bad coil I guess.


BTW, I found a never-used 1.4Ohm ballast resistor in my drawer. Still no help w/the starting issue.

 

[dp]

My resistor fell apart. Can I just use ANY universal one?

My recommend: Get a Bosch Blue Coil, and at the same time get rid of the ballast resistor.

Note: you can run a blue coil with the resistor but it will limit the spark, i.e. you do not need a ballast resistor with a blue coil. Since you're looking at both the resistor AND your old coil, just get a new Bosch Blue Coil and be done with it...hope this helps