Attack of the coil killer!

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4mulaSvaliant

4mulaSvaliant

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Hey guys whats up, I hope someone has some ifo because this is getting irritating!
I have killed 2 coils in a matter of 5 starts! The only thing that has changed recently is the addition of a new alternator. My old alt. had a bad diode, at idle speeeds. I have replaced it and man what a difference. Howeveer this is the only thing I can think of that will continue to kill the coil. Dont ask me how, I just figure thats the only thing that has changed.
I did have the coil mounted above the intake, so it may have gotten hot, but it was there for quite some time and much longer run times than when it seemed to fail. Also it was mounted on its side. This is the second coil that has "leaked". It has a small amount of oil, tha seemed to leak out.
I installed another coil, this time a good old factory spare, it was started only 2 times, and yesterday after stripping the quarter panel it wouldnt start again, and I have no spark again. The coil before the stock install was only several months old and it was an Accell "super coil" nothing special really.
Any ideas? Voltage reg? ballast resiter? what else can it be?
 
4mulaSvaliant said:
Hey guys whats up, I hope someone has some ifo because this is getting irritating!
I have killed 2 coils in a matter of 5 starts! The only thing that has changed recently is the addition of a new alternator. My old alt. had a bad diode, at idle speeeds. I have replaced it and man what a difference. Howeveer this is the only thing I can think of that will continue to kill the coil. Dont ask me how, I just figure thats the only thing that has changed.
I did have the coil mounted above the intake, so it may have gotten hot, but it was there for quite some time and much longer run times than when it seemed to fail. Also it was mounted on its side. This is the second coil that has "leaked". It has a small amount of oil, tha seemed to leak out.
I installed another coil, this time a good old factory spare, it was started only 2 times, and yesterday after stripping the quarter panel it wouldnt start again, and I have no spark again. The coil before the stock install was only several months old and it was an Accell "super coil" nothing special really.
Any ideas? Voltage reg? ballast resiter? what else can it be?
Click to expand...


two things kill coils. to much voltage or too much heat. and I don't think heat is your problem.
cheers
 
I'm guessing 2 bad coils in stock there. Put a new one on it .
 
As was said.. check the voltage at teh positive side of the coil with the engine running. Should be at least 8, but less than 10. What year car is it?
 
some coils need to be mounted verticle and others can go horizontal. Even the horizontal ones still have a top and bottom side. Check you paperwork and make sure it is correct.
 
make sure the ballast resistor is in line before the coil,and factory coils can be mounted either way hope this helps
 
Im going to check the input voltage and make sure the wiring is all good. Where do I look next if the voltage isnt getting to the coil? I dont think this is the case but, if this turns out to be intermitent, then Ill have to start looking for issues ahead of the coil.
 
When you turn the ignition key to the start position the ballast is by passed until the key is let go and goes back to the run position. With engine off you might want to check the + side of the coil to see if that is happening. Start position full 12 volts, run position around 8 volts.
 
I had a similar problem and it turned out the main wiring harness behing the instrument cluster was shorting out on the dash frame...
 
You may have purchased a "bad" alternator or if external, have a bad voltage regulator. If you have a voltmeter, place it across the battery terminals and read the voltage BEFORE starting the engine. It should read 12.60 volts if at full charge or very close to it.

If you can get another coil, start the engine and run at about 1500 rpm (a fast idle). You don't really need a tach-just guess. Place the voltmeter across the terminals now and see what it reads. It should be higher than the previous reading but not above 14.5. (high 13's would be great). If any higher than 14.5 volts, you probably have a bad voltage regulator. This could result in almost everything electrical lights, wiper motor, radio, blower motor, etc., being damaged or burning up. Good luck.
 
well I have checked the voltage and on BOTH sides of the coil I am reading 10.8 volts with the ignition in the run position. Dont have any help at the moment so I cant check the voltage when the key is in the start position. Anybody have any ideas from here? I checked and I have no spark coming out of the coil wire directly.
This is a 69 valiant but I converted it to electronic from a 73 valiant. I am sure that it isnt a wiring issue since I have had this car running for years the way it is wired. I am wondering if maybe it is a voltage regulator issue. Since the only thing that has changed recently is the Alt.
Lets see whatcha got guys?
 
10.8 is a little high for a street car. Not excessive, but high. The position of the coil should make little difference. If they are leaking, they are defective. Remember, factory coils on a few million mopars lived fine on the engine, on their side. I use MSD BlasterII coils for 90% of my stuff. I have not had any that failed, and none leaked. And, they seem to be stable to way past 6500rpm. I would recommend replacing the ballast resistor and check the voltage again. If you can get it down to 9, you should have no issues with any coil.
 
yeah I think thats the next thing Ill be doing is replacing the Ballast resister. Like everybody I hate searching for electrical gremlins. It especially bad when you have limited electrical knowledge. I think Ill go get a new ballast resister and new voltage regulator. They arent too expensive. We'll see what happens from there.

Anybody else have any input?
 
I think to have you monitor the voltage at the coil, at idle and above idle. See if its getting too much at idle. It should get only 6-9 volts at idle.

Just a thought...
 
whats the alternator voltage, It should allways be less than 15 volts with the engine running, the ballast resistor drops the voltage after the starter is disengaged. So the voltage across the ballast resistor +the coil voltage should equal the battery voltage. If it does than that verifies coil wireing ok, If the sorce voltage is high than you have an altornator/regulator problem'
 
Thx guys. Is there a way to check the Ballast resister? I hate to start replacing parts to find a problem. We all know how that goes. If I can find a way to test the B.R. then Ill go from there. I dunno why but I have a feeling it is either thaBR or the Voltage reg.
 
The BR should have about .9-1.2 ohms between the 2 posts. If the incoming voltage is higher than 13.7-14.4(while running), then check the VR.
 
you can check it with an ohm meter. It is very unlikely that it is the problem they are 99.9% of the time either open or ok. I checked one i had and it was 10 ohms.
 
And I thank both of you! Ill try to check it out tonight. I dont get to drive this on at the moment, but I hate knowing that it wont just start if I go out and hit the key!
 
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