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Chry 318 Ign. coil burning up
I have an early 1980's modle 318 Chrysler engine installed in a
mudboat. About 2 years ago I developed a problem with the Ignition coil burning up. The engine has the original electronic ignition system installed, but has been completely rewired by a Dodge dealership, the control module, ballast resistor, and the distributor pick-up assy. have been replaced. However, I continue to have the problem. The engine runs perfectly for about 3 months and then without any warning, will backfire and die. There will be no ignition fire until the coil is replace, then the engine will start up and run fine for another few months. Any help or suggestions with this problem would be GREATLY appreciated. Thanks Ronnie |
Check to make sure there is a good ground to the coil case.
wrote in message ps.com... I have an early 1980's modle 318 Chrysler engine installed in a mudboat. About 2 years ago I developed a problem with the Ignition coil burning up. The engine has the original electronic ignition system installed, but has been completely rewired by a Dodge dealership, the control module, ballast resistor, and the distributor pick-up assy. have been replaced. However, I continue to have the problem. The engine runs perfectly for about 3 months and then without any warning, will backfire and die. There will be no ignition fire until the coil is replace, then the engine will start up and run fine for another few months. Any help or suggestions with this problem would be GREATLY appreciated. Thanks Ronnie |
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Dave Hall wrote: On 19 Dec 2004 19:24:09 -0800, wrote: I have an early 1980's modle 318 Chrysler engine installed in a mudboat. About 2 years ago I developed a problem with the Ignition coil burning up. The engine has the original electronic ignition system installed, but has been completely rewired by a Dodge dealership, the control module, ballast resistor, and the distributor pick-up assy. have been replaced. However, I continue to have the problem. The engine runs perfectly for about 3 months and then without any warning, will backfire and die. There will be no ignition fire until the coil is replace, then the engine will start up and run fine for another few months. Any help or suggestions with this problem would be GREATLY appreciated. Sounds to me like your coil is being "fried" because there is too much voltage being run through it. Most coils are designed to run at the full 12V when starting, but then switch in a dropping resistor which drops the voltage down to about 8V when running. If this dropping resistor is absent, the coil will get the full charge at all times. Another thing to check is your charging voltage. If your alternator regulator is acting up, and the charge voltage runs up to 16 or 17 V the same thing could happen. Although, you'd probably notice your batteries boiling over and very bright lights as well. Dave I appreciate all the responses very much. The resistor resistance is app. 1.2 ohms and running voltage is 8.2 volts. Alternator output is 14.4 volts. The coil is mounted directly to the block and the bracket seems to be tight and clean, no signs of corrision. I tried install a higher resistance resistor and dropped the running voltage to 7 volts, but that made the ign. fire too weak. I have tried using Mopar coils as well as aftermarket coils with no noticeable differance. Someone suggested using a HEAVY DUTY coil, where can I buy one and what do I ask for? This problem certainly has myself, the Dodge dealership and several local independent mechanics scratching our heads. Thanks again Ronnie |
On 20 Dec 2004 16:52:07 -0800, "wtbuck12"
wrote: ~~ snippage ~~ I appreciate all the responses very much. The resistor resistance is app. 1.2 ohms and running voltage is 8.2 volts. Alternator output is 14.4 volts. The coil is mounted directly to the block and the bracket seems to be tight and clean, no signs of corrision. I tried install a higher resistance resistor and dropped the running voltage to 7 volts, but that made the ign. fire too weak. I have tried using Mopar coils as well as aftermarket coils with no noticeable differance. Someone suggested using a HEAVY DUTY coil, where can I buy one and what do I ask for? This problem certainly has myself, the Dodge dealership and several local independent mechanics scratching our heads. Auto parts places can come up with a heavier duty coil. Might want to try a speed shop also. BUT..... I wonder if this is a heat related problem. Based on what you just posted, it all sounds normal. Which makes me wonder what is breaking down the insulation (which is what normally happens with a coil). There is a lot of internal heat in a coil from it's normal functioning, but perhaps it's located close to a heat source like exhaust manifold? The only other thing I can think of is that the coil is inducting a external charge by being located too close to a EM source - perhaps a generator or something? Just shots in the dark. Later, Tom |
On Tue, 21 Dec 2004 01:02:20 GMT, Short Wave Sportfishing
wrote: I wonder if this is a heat related problem. Based on what you just posted, it all sounds normal. Which makes me wonder what is breaking down the insulation (which is what normally happens with a coil). There is a lot of internal heat in a coil from it's normal functioning, but perhaps it's located close to a heat source like exhaust manifold? The only other thing I can think of is that the coil is inducting a external charge by being located too close to a EM source - perhaps a generator or something? ====================================== All of that, plus you should also check your alternator and voltage regulator. 14.4 volts is a bit on the high side and may be contributing to the problem. 13.8 is a more normal "float" voltage after the batteries are fully charged. |
Maybe wrong coil. Maybe should be an internal resister coil and you are
putting in a no resister coil. They both need external ballast resistors. Petronic's makes a coil that will work with electronic ignition with no ballast resistor. The ballast resistor is to reduce peak current flow through the points, adding a lot of lifespan to them. "Short Wave Sportfishing" wrote in message ... On 20 Dec 2004 16:52:07 -0800, "wtbuck12" wrote: ~~ snippage ~~ I appreciate all the responses very much. The resistor resistance is app. 1.2 ohms and running voltage is 8.2 volts. Alternator output is 14.4 volts. The coil is mounted directly to the block and the bracket seems to be tight and clean, no signs of corrision. I tried install a higher resistance resistor and dropped the running voltage to 7 volts, but that made the ign. fire too weak. I have tried using Mopar coils as well as aftermarket coils with no noticeable differance. Someone suggested using a HEAVY DUTY coil, where can I buy one and what do I ask for? This problem certainly has myself, the Dodge dealership and several local independent mechanics scratching our heads. Auto parts places can come up with a heavier duty coil. Might want to try a speed shop also. BUT..... I wonder if this is a heat related problem. Based on what you just posted, it all sounds normal. Which makes me wonder what is breaking down the insulation (which is what normally happens with a coil). There is a lot of internal heat in a coil from it's normal functioning, but perhaps it's located close to a heat source like exhaust manifold? The only other thing I can think of is that the coil is inducting a external charge by being located too close to a EM source - perhaps a generator or something? Just shots in the dark. Later, Tom |
wtbuck12 wrote:
You say it's a "mud" boat can we assume the engine works hard at high revs & power??? Do you still have a failed coil??? how have the coils failed?? Primary open circuit?? leaks to case (ground)?? High internal resistance??? Any cracks or physical signs ?? If it "appears" fine with a multimeter & has no outward signs, then open it up (it's junk anyway yes??) & have a look for signs of a breakdown in the secondary windings, the backfire on dying might be a good clue that high resistance & heat buildup has caused a high voltage leak which kills the coil at the same time. If you see such signs of over heating inside, shorts or open circuit when hot then maybe consider; Position on the engine; does it get overly hot near a manifold exhaust EGR heat path?? or an exhaust manifold?? Are the plugs, all leads (incl coil lead) cap, rotor etc all OK with a standard plug gap?? Some people like larger than usual plug gap. However anything that offers resistance (which should show on a multimeter or much better an engine analyser, will even tell you which lead or plug is to blame:-)) can firstly make the coil run hotter & if the resistance is too high the coil's internal insulation can fail. i.e. never run engine with lead disconnected the spark will try to escape anywhere it can, including inside the coil itself. So make sure the rest of the system is up to snuff. You say the dist. "pickup" has been replaced?? but is the low voltage switching system correct for the coil(s), most are expecting a capacitor discharge type of primary supply (no dwell) but if you have an old system it's worth investigating if the type of primary supplied is OK for the coil, assuming the pickup does nothing more than what an old set of points/condenser did. Getting desperate now:-) Sorry. K Dave Hall wrote: On 19 Dec 2004 19:24:09 -0800, wrote: I have an early 1980's modle 318 Chrysler engine installed in a mudboat. About 2 years ago I developed a problem with the Ignition coil burning up. The engine has the original electronic ignition system installed, but has been completely rewired by a Dodge dealership, the control module, ballast resistor, and the distributor pick-up assy. have been replaced. However, I continue to have the problem. The engine runs perfectly for about 3 months and then without any warning, will backfire and die. There will be no ignition fire until the coil is replace, then the engine will start up and run fine for another few months. Any help or suggestions with this problem would be GREATLY appreciated. Sounds to me like your coil is being "fried" because there is too much voltage being run through it. Most coils are designed to run at the full 12V when starting, but then switch in a dropping resistor which drops the voltage down to about 8V when running. If this dropping resistor is absent, the coil will get the full charge at all times. Another thing to check is your charging voltage. If your alternator regulator is acting up, and the charge voltage runs up to 16 or 17 V the same thing could happen. Although, you'd probably notice your batteries boiling over and very bright lights as well. Dave I appreciate all the responses very much. The resistor resistance is app. 1.2 ohms and running voltage is 8.2 volts. Alternator output is 14.4 volts. The coil is mounted directly to the block and the bracket seems to be tight and clean, no signs of corrision. I tried install a higher resistance resistor and dropped the running voltage to 7 volts, but that made the ign. fire too weak. I have tried using Mopar coils as well as aftermarket coils with no noticeable differance. Someone suggested using a HEAVY DUTY coil, where can I buy one and what do I ask for? This problem certainly has myself, the Dodge dealership and several local independent mechanics scratching our heads. Thanks again Ronnie |
On 20 Dec 2004 16:52:07 -0800, "wtbuck12"
wrote: Dave Hall wrote: On 19 Dec 2004 19:24:09 -0800, wrote: I have an early 1980's modle 318 Chrysler engine installed in a mudboat. About 2 years ago I developed a problem with the Ignition coil burning up. The engine has the original electronic ignition system installed, but has been completely rewired by a Dodge dealership, the control module, ballast resistor, and the distributor pick-up assy. have been replaced. However, I continue to have the problem. The engine runs perfectly for about 3 months and then without any warning, will backfire and die. There will be no ignition fire until the coil is replace, then the engine will start up and run fine for another few months. Any help or suggestions with this problem would be GREATLY appreciated. Sounds to me like your coil is being "fried" because there is too much voltage being run through it. Most coils are designed to run at the full 12V when starting, but then switch in a dropping resistor which drops the voltage down to about 8V when running. If this dropping resistor is absent, the coil will get the full charge at all times. Another thing to check is your charging voltage. If your alternator regulator is acting up, and the charge voltage runs up to 16 or 17 V the same thing could happen. Although, you'd probably notice your batteries boiling over and very bright lights as well. Dave I appreciate all the responses very much. The resistor resistance is app. 1.2 ohms and running voltage is 8.2 volts. Alternator output is 14.4 volts. The coil is mounted directly to the block and the bracket seems to be tight and clean, no signs of corrision. I tried install a higher resistance resistor and dropped the running voltage to 7 volts, but that made the ign. fire too weak. I have tried using Mopar coils as well as aftermarket coils with no noticeable differance. Someone suggested using a HEAVY DUTY coil, where can I buy one and what do I ask for? This problem certainly has myself, the Dodge dealership and several local independent mechanics scratching our heads. Well, Sherlock Holmes once said something along the lines that when you eliminate the obvious, what's left, no matter how improbable, must be the answer. If your operating voltage is correct, and the coil is mounted properly and not exposed to the corrosive effects of water then I have to think that perhaps the shape of the ignition pulse is too sharp. If there is a sharp spike, which exceeds the operating voltage, over a period of time, it could cause the insulation in the coil to break down. The only way to see this is with an oscilloscope. The cure is simple though, a capacitor from the "cold" side of the coil to ground, somewhere around .1uF should do it. Dave |
Dave Hall wrote in message ... On 20 Dec 2004 16:52:07 -0800, "wtbuck12" wrote: Dave Hall wrote: On 19 Dec 2004 19:24:09 -0800, wrote: I have an early 1980's modle 318 Chrysler engine installed in a mudboat. About 2 years ago I developed a problem with the Ignition coil burning up. The engine has the original electronic ignition system installed, but has been completely rewired by a Dodge dealership, the control module, ballast resistor, and the distributor pick-up assy. have been replaced. However, I continue to have the problem. The engine runs perfectly for about 3 months and then without any warning, will backfire and die. There will be no ignition fire until the coil is replace, then the engine will start up and run fine for another few months. Any help or suggestions with this problem would be GREATLY appreciated. Sounds to me like your coil is being "fried" because there is too much voltage being run through it. Most coils are designed to run at the full 12V when starting, but then switch in a dropping resistor which drops the voltage down to about 8V when running. If this dropping resistor is absent, the coil will get the full charge at all times. Another thing to check is your charging voltage. If your alternator regulator is acting up, and the charge voltage runs up to 16 or 17 V the same thing could happen. Although, you'd probably notice your batteries boiling over and very bright lights as well. Dave I appreciate all the responses very much. The resistor resistance is app. 1.2 ohms and running voltage is 8.2 volts. Alternator output is 14.4 volts. The coil is mounted directly to the block and the bracket seems to be tight and clean, no signs of corrision. I tried install a higher resistance resistor and dropped the running voltage to 7 volts, but that made the ign. fire too weak. I have tried using Mopar coils as well as aftermarket coils with no noticeable differance. Someone suggested using a HEAVY DUTY coil, where can I buy one and what do I ask for? This problem certainly has myself, the Dodge dealership and several local independent mechanics scratching our heads. Well, Sherlock Holmes once said something along the lines that when you eliminate the obvious, what's left, no matter how improbable, must be the answer. If your operating voltage is correct, and the coil is mounted properly and not exposed to the corrosive effects of water then I have to think that perhaps the shape of the ignition pulse is too sharp. If there is a sharp spike, which exceeds the operating voltage, over a period of time, it could cause the insulation in the coil to break down. The only way to see this is with an oscilloscope. The cure is simple though, a capacitor from the "cold" side of the coil to ground, somewhere around .1uF should do it. Dave Dave's response rang a dusty old bell in my head. I seem to recall an issue with electronic ignition systems for cars, particularly when they first came out and were being retro-fitted to the older points and condenser systems. Coils were dying a quick death due to the sharper pulse of the electronic ignition. A higher performance coil was required to cure the problem. Eisboch |
On Tue, 21 Dec 2004 12:16:55 GMT, "Eisboch"
wrote: ~~ snippage ~~ Dave's response rang a dusty old bell in my head. I seem to recall an issue with electronic ignition systems for cars, particularly when they first came out and were being retro-fitted to the older points and condenser systems. Coils were dying a quick death due to the sharper pulse of the electronic ignition. A higher performance coil was required to cure the problem. The man is hot today. Another good point. Later, Tom |
Thanks again for the input. The coil is mounted exactly where and how
it has been mounted for the last ten years, and nothing has changed with the engine. So I think, since the problem has developed in the last two years, we can eliminate mounting or external heat induction. I will check with a local speed shop and see what I can find out about a high performance coil, at this point I will try anything! I will also try cutting open an old coil if I still have one of the burned out ones, if not I will check the next one that burns. Hopefully, since I just had to change it, it will not be for a while!! LOL. Thanks Ronnie |
On Tue, 21 Dec 2004 16:07:58 GMT, Short Wave Sportfishing
wrote: On Tue, 21 Dec 2004 12:16:55 GMT, "Eisboch" wrote: ~~ snippage ~~ Dave's response rang a dusty old bell in my head. I seem to recall an issue with electronic ignition systems for cars, particularly when they first came out and were being retro-fitted to the older points and condenser systems. Coils were dying a quick death due to the sharper pulse of the electronic ignition. A higher performance coil was required to cure the problem. The man is hot today. Another good point. I try...... Life is a series of puzzles looking to be solved. Dave |
I'm sorry, but I haven't been following this thread. Here's my 2 cents.
The older Chrysler automotive ignition systems with points and condenser had a resistor in series with the coil. This resistor was bypassed when the ignition key was in the start position, but placed in series with the coil with the ignition switch in the run position. If the ignition switch was bad or if someone had done something to the resistor (like jumpering it out) then the coil would not last long. It was common for these resistors to go bad causing the engine to run with the ignition switch in the start position but not in the run position. The quick fix was to jumper out the resistor, but if you didn't replace it, then the coil would go bad. I used to keep a spare resistor in my glove compartment after this happened to me the second time. I think I used about 5 of them in the life of the car. -- Charley "Short Wave Sportfishing" wrote in message ... On Tue, 21 Dec 2004 12:16:55 GMT, "Eisboch" wrote: ~~ snippage ~~ Dave's response rang a dusty old bell in my head. I seem to recall an issue with electronic ignition systems for cars, particularly when they first came out and were being retro-fitted to the older points and condenser systems. Coils were dying a quick death due to the sharper pulse of the electronic ignition. A higher performance coil was required to cure the problem. The man is hot today. Another good point. Later, Tom |
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