Possible coil failure - which other parts do I replace at the same time?

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Old Aug 25, 2013 | 09:40 AM
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Possible coil failure - which other parts do I replace at the same time?

Hi!

My 72' CS was a bit hard to start earlier today, and when I was going to take another ride with a "not cold" engine this afternoon, it wouldn't start at all.

I pulled a spark plug, and there was no spark. Pulled the wire from the coil to the dizzie, and there was no spark as far as I could see there either.

So, I'm looking at buying a new coil right now. And I think I should buy new ign.wires aswell, since they're OLD, or looks that way. But should I also replace the dizzie cap? And what about the capacitor? Where is that located on the car? There's a pic in my webshop, but it's so bad I almost can't tell it's even a cap!

Is there a mileage limit or are these parts just "swap when broken"?

All tips and experiences are most welcome!

Thanks!
Old Aug 25, 2013 | 09:55 AM
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What about the points, condenser, rotor, cap, and electrical supply?

Have you checked those?

Just because there's no spark doesn't mean the coil is bad - it could be lots of things.

Consider doing some diagnosis before replacing parts that you don't know are bad.

- Eric
Old Aug 25, 2013 | 10:03 AM
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First, check for voltage at the coil (+) terminal with the ignition on - should be 12V with the points open, about 9V with the points closed.

Next, connect a spark plug wire with a spark plug on it to the coil, disconnect the (-) coli wires, and connect a jumper wire to the (-) coil terminal.
Ground the spark plug, turn on the ignition, touch the jumper to a good ground, then quickly pull it away - you should get a good spark.
Do it again a few times, because it's fun.
No spark = bad coil.
Spark = good coil.

Next, pull the distributor cap and rotor.
Inspect them for damage or carbon trails.
Check resistance between the distributor wire (that used to be connected to the coil) and ground while opening and closing the points - should be 0Ω closed, ∞Ω open.
If you have resistance, the points are bad.

If the cap, rotor, points, and coil are all good, and you've got a good supply voltage, then the condenser is probably bad.

- Eric
Old Aug 25, 2013 | 01:29 PM
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Didn't try "rewiring" the - on the coil-trick do get a spark, but didn't get a spark with the method we did try. Not sure if it would be correct though, so it may not have given a spark anyway.

Had a mechanic over, he checked the distributor and point, he couldn't find anything wrong, except a little carbon that he removed. Measured good contact with ohm meter after, so we hope it's OK.

We're kind of back to the coil again, and with the low cost of parts and the high cost of shipping, I just ordered coil, rotor, spark plugs, and condenser, just in case.

The coil looks really, really old, while the cap and wires seem at least only a few years old. Or maybe 10 at most.

Thanks for the tips though, I guess we partly did try some of them out before I read your response just now!
Old Aug 25, 2013 | 04:37 PM
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You're welcome.

Originally Posted by Miniboom
... with the low cost of parts and the high cost of shipping, I just ordered coil, rotor, spark plugs, and condenser, just in case.
Where do you live? Can't you just go to the auto parts store and get them?

- Eric
Old Aug 25, 2013 | 04:43 PM
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Replace one at a time, you will learn something and have some spare parts once you find the bad component.
Old Aug 26, 2013 | 10:13 AM
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Originally Posted by MDchanic
You're welcome.


Where do you live? Can't you just go to the auto parts store and get them?

- Eric

I live in Norway, we have ONE auto parts store for American cars in my COUNTY. It's open 8-4. And I don't work anywhere near it.

Getting it by mail is far better (half the gasoline cost to the shop).
Old Aug 26, 2013 | 10:14 AM
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Originally Posted by m371961
Replace one at a time, you will learn something and have some spare parts once you find the bad component.
Sounds like good advice, will do that. Thanks!
Old Aug 26, 2013 | 10:19 AM
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Originally Posted by Miniboom
I live in Norway,
Oh. That explains it.

Never mind.

Good English, by the way.

- Eric
Old Sep 1, 2013 | 06:24 AM
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Sooo, I'm back again! Go figure... If it wasn't evident before, I'd like to point out that I'm about as good a mechanic as the average hedgehog.

I have progress (from "nothing" to "coughing and almost firing"), but still, no starting engine!

I changed the points, and adjusted to 0.016", and then I got some coughs and voltage drop across the coil, hence primary side gets current.

I then replaced the spark plugs, since they were rusty, black on the porcelain, some were a little black from soot, and a few were tan. I'm not sure if it's normal or a really bad sign they show different signs of wear, but...

No change after change of plugs. I changed the coil too - same story.

Is adjusting the points THAT hard? Since that's what changed the symptoms from "nothing" to "coughing", I'm kind of guessing that's where the main problem is still.

Also, I'm wondering if my shop has sent the wrong set of points? They don't have the capacitor (condenser) that the old points breaker arm had fitted, which I find a little weird. I mean, there's not even a hole or anything for a condenser to be fitted to the points whatsoever.

Also, the whole points assembly is made from what appears to be copper - and the distributor is alloy? If I remember correctly, that mix will corrode?

Getting a little tired of this crap, I'm seriously leaning towards electronic ignition conversion, which should fit a dumbass like me a little better. Maybe.


Any tips?
Old Sep 1, 2013 | 06:55 AM
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Since your new points are not a Uniset, you are going to need a condenser. It would mount with one screw on the other side of your distributor. The wire would run to the same connection as the black wire on the points.

Since you changed your point gap, your timing has also changed, so you may have to rotate the distributor a little one way or the other to get your engine to start.
Old Sep 1, 2013 | 07:13 AM
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Oh! Holy...In fact, I did order a capacitor, but I though it was for the coil? It looks identical to the one on the old coil, and bigger than the one on the old points, so I fitted it to the coil like the old one.

Should I try to reuse the old capacitor for the coil, and try the new one in the distr.?

Is it supposed to be of a certain value? I mean, the condenser - in Farads?
Old Sep 1, 2013 | 07:25 AM
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You can put the old one on the coil where it was, that one is for radio noise filtering. You have to have the one in the distributor as the car will not run without it. Sorry I don't know what the value is for them.
Old Sep 1, 2013 | 04:40 PM
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Yes, put the old condensor on the coil. The new one attached to the points as OC says.
I always thought the one inside the distributor was there for longer point life as it absorbs the voltage when the points open. Yes when they short out the car will not run. I was taught that if one malfunctions, you will see a build up on one of the point contacts from the contacts arcing material from one to the other. If you tried starting your car without one, you may have ruined the points. Check the contact surfaces and re-gap them.Never tried to run a car without the condensor, would think it would fire until the points were ruined.
Old Sep 1, 2013 | 05:28 PM
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It will spit and backfire and run like crap because the spark would be long on some cylinders and fire short on others intermittently.
Old Sep 1, 2013 | 08:46 PM
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Nice looking Cutlass by the way.
Old Sep 1, 2013 | 09:24 PM
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Note that, if you are troubleshooting, the physical location of the condenser does not matter, only the electrical location.
So long as the condenser is connected in parallel with the points, between the (-) coil terminal and ground, it will work fine.

If you need to experiment, connecting it directly to the (-) terminal is completely acceptable.

- Eric
Old Sep 2, 2013 | 01:05 AM
  #18  
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possible coil failure

Originally Posted by Miniboom
Hi!

My 72' CS was a bit hard to start earlier today, and when I was going to take another ride with a "not cold" engine this afternoon, it wouldn't start at all.

I pulled a spark plug, and there was no spark. Pulled the wire from the coil to the dizzie, and there was no spark as far as I could see there either.

So, I'm looking at buying a new coil right now. And I think I should buy new ign.wires aswell, since they're OLD, or looks that way. But should I also replace the dizzie cap? And what about the capacitor? Where is that located on the car? There's a pic in my webshop, but it's so bad I almost can't tell it's even a cap!

Is there a mileage limit or are these parts just "swap when broken"?

All tips and experiences are most welcome!

Thanks!
This may be off topic but,does it have fuel an compression?
Old Sep 2, 2013 | 11:29 AM
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Thanks for all the good tips, and I will test out with relocating and fitting the condenser if I don't have to work overtime every night until the Ignitor-kit arrives. Yeah... I saw multiple users here had upgraded to the one that fits in the distributor, and seemed very pleased with the kit, so I ordered one last night from a US eBay dealer.

I think my spare time (not to say my forehead, because if I'll stop by the road from non-working points some time, I'll be using it to bend my steering wheel), is worth more than the $75 spent on the upgrade/modernization.

Thanks for the comment on the car - a Cutlass isn't (wasn't) my dream car per sé, I took it in as a trade a couple of years ago, but I think I have to reconsider my preferences after fitting the new wheels on it recently. It's another car now, both to drive and to look at.

After trying to sell the car CHEAP (for the Norwegian market) for a year, I'm not so eager to see it go anymore, so I increased the price in the ad - at least now I won't lose as much money, if someone eventually wants it. If not, I'll be happy to own it for a long time as well.

Selling Oldsmobiles in Norway isn't exactly easy... I had mine priced $2000 less than the next online, and still no sale.

I'd like to see it with 2" drop spindles, though, and lower it a tad in the rear as well. When I get some cash on my hands again, I think I'll order a set. I don't know, but reasonably sized wheels and a little lowering looks very nice to me!

Sorry for the long post!
Old Oct 13, 2013 | 03:47 AM
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I forgot to reply here, but I bought and fitted an IGNITOR-kit (points eliminator with magnetic trigger) from fleaBay. Barely got to crank the engine before it started RIGHT after fitment. I just have to adjust the timing now, because it sounds a bit agressive. My car hasn't been running this well for years, though, that's for sure. Revs much faster than before.

Highly recommended upgrade/fix for non-mechanical guys like myself, instead of messing with point, condensers and other outdated hardware, or paying a workshop/mechanic to swap and adjust that same hardware.

I don't know much about cars, but had the car running in less than an hour. The kit was EASY to assemble with the distributor on the car as well, even though the manual says to remove it.

Thanks for the helpful comments, everyone!
Old Oct 13, 2013 | 08:05 AM
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Depending on the kit you installed it may or may not use the resistor wire, the system may require a full 12v on the coil+.
Old Oct 17, 2013 | 01:28 PM
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Oh, thanks for replying! I was wondering about the resistor wire - how do I know if I have (to have) one??
Old Oct 17, 2013 | 03:52 PM
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It's a tannish very stiff wire crimped with the wire that feeds from the starter and connected to your coil+ terminal.
Old Nov 1, 2013 | 05:24 AM
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But if I measure 12V at the coil, I don't have the resistor wire, right? Because I did, so I think I might be good.
Old Nov 1, 2013 | 05:56 AM
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If you had a points distributor then it had a resistor wire. You have to measure the voltage on the coil + with the engine running. It should be close to what you see across the battery if you do not have one.
Old Nov 8, 2013 | 12:34 AM
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Thanks, I will measure again when I get the car out from winter storage, in mid april 2014 or so.
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