| Author |  Topic  |
GeoffC
V4 Mad
United Kingdom
507 Posts |  Posted - 01 Sep 2021 : 13:33:21  
| Derek - But the coil has a 12 volt supply to the +ve side so because I stupidly connected the points to that side of the coil, as soon as the points closed it caused a direct short to earth hence the meltdown.
Just got another set of points and screw, from Malbrads super fast delivery service (I don't know how the postal system works so fast for him - when I send anything first class it takes a week!!!). So will have another attempt this afternoon- fingers crossed. |  |
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GeoffC
V4 Mad
United Kingdom
507 Posts | Posted - 01 Sep 2021 : 16:29:41
| | Still no luck. Fitted new points and smelt burning again so switched off ignition quickly. Points VERY hot to the touch burnt my finger! Also noticed power lead to coil had melted so obviously still a short somewhere even though points are connected to -ve side of coil So decided to bypass ignition switch and wiring loom and put a simple 12 volt supply direct to the +ve side of coil. Also changed dizzy cap and rotor arm. Points still getting hot and No spark whilst cranking. So is the condenser burnt out as a result of my earlier mess up so too much current going through the points or am I still missing something obvious. All getting beyond a joke now I'm running out of ideas. | |
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 02 Sep 2021 : 13:08:06
| This is starting to sound to me like the coil might be at fault: maybe the internal insulation on the LT coils have broken down, and now the whole unit is acting as a dead short. This would allow too much current to flow through the points (as you observe) and also mean no spark.
I've never actually tested a coil, but you could maybe try with an in-line HT tester connected to the coil HT output and Earth, and then disconnect the coil -ve from the points and try manually making a brief connection to Earth. That should make an HT pulse.
Another way to test for a short without a voltmeter would be to get a high output bulb (like a headlight bulb), and connect it across the battery, and get an idea of how bright it glows. You could then wire it in series with the coil, and the resistance of the coil should make the light glow less bright. If it stays the same then I'd think it's acting as a short, which could be your problem. When doing this test best to disconnect the coil from the ignition and just use the 'test' wiring.
Hope this is of some use,
Joe
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EdinburghJoe
V4 Fan
United Kingdom
162 Posts | Posted - 02 Sep 2021 : 13:46:21
| On the subject of the condenser, there are two things you can do to hurt them:
1) They will break down and become a permanent short if subjected to voltages well in excess of 12v, but you haven't done that
2) If they are connected the wrong way round they will break down instantly, but that's hard on a car given that the metal 'can' always goes to earth (-ve). | |
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christophe
V4 Fanatic
France
227 Posts | Posted - 02 Sep 2021 : 17:57:36
| | I saw many cars with the coil hooked backwards. They ran poorly but did not fried their points. To me, it looks like as if the insulation was defective between the coil and the points. This happens most of the time where the cable ig getting into the distributor. Maybe an insulating washer is missing somewhere. It is time to use your trusty ohmmeter. Check that there is no continuity between the points when they are opened. If your coil is still OK, you should get a 3-4 ohms resistance in the primary circuit and several kilo ohms in the secondary cicuit, depending of what type of coil you got. | |
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GeoffC
V4 Mad
United Kingdom
507 Posts | Posted - 02 Sep 2021 : 22:49:18
| | Thanks for the advice re the coil etc. It is a new coil after I tested the original and found a high resistance on the primary circuit. I will check that I haven't blown the new one! Have ordered another condenser as I may have damaged that when it all shorted out. I will also run a new power cable from the ignition switch to the coil as the original wire is showing signs of a melt down - all a but of a mess but I'm running out of ideas so hopefully the new condenser will lessen the current on the points. | |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 03 Sep 2021 : 12:28:22
| Follow what Christophe says. With a meter you should be able to see if the LT wire at he dizzy connection is shorted out to the body. The order of the washers, both the metal and nylon ones, are critical here to stop the through bolt from shorting to the body. The shouldered nylon ones should bridge the hole from both sides. Also note that the spring can also short to the casing at this point. Don't do up the retainer nut too tight as this can squash the insulators enough to cause the short.
A general view here scroll down. https://www.912bbs.org/forum/threads/distributor-points-adjuster-screw.55183/ | |
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GeoffC
V4 Mad
United Kingdom
507 Posts | Posted - 09 Sep 2021 : 13:34:17
| | Result!!! Sonett now running, the replacement condenser took ages to arrive but it's sorted the overheating points. The wire from the ignition switch had half melted so have replaced that, set the timing and it started first turn of the key! Pouring with rain here and as the back window leaks I'll have to wait to see if the intermittent fault has gone. | |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 10 Sep 2021 : 12:45:25
| | Try Captain Tolley's Creeping Crack Cure on your rear window seal. Must be 100% dry with no trapped water. Repeat until it stops soaking in. Keep it off your paint, as it's hard to remove when it dries. | |
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GeoffC
V4 Mad
United Kingdom
507 Posts | Posted - 10 Sep 2021 : 14:15:06
| | Not heard of that one I'll have a look thanks! | |
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john-ayr
Starting Member
26 Posts | Posted - 10 Sep 2021 : 16:20:19
| GeoffC captain Tolley's is a crack cure used by the yacht guys for many years. Probably get it on an on line chandlers.
Regards john. | |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 11 Sep 2021 : 14:27:39
| | eBay. | |
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GeoffC
V4 Mad
United Kingdom
507 Posts | Posted - 11 Sep 2021 : 17:05:49
| | Thanks for the tips I'll have a look at where the waters getting in - job for another day. Good news - it has been 10 miles, engine running well pulling strongly and more importantly no ignition cut out!!! Could have been the wire from the ignition switch, half burnt through or the electronic ignition but it appears to have been sorted at last!!! | |
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Doive
V4 Fan
United Kingdom
160 Posts | Posted - 11 Jul 2022 : 16:37:51
| Our 95 has a similar running issue, it developed suddenly the last day I had it out - the 1770cc upgrade is now well run in and I was giving it a few energetic runs around local B-roads, when approaching a roundabout it suddenly cut out as the OP described. On later investigation I noticed the earth braid in the distributor is hanging on by a single strand. I can only assume the lack of continuity is causing the electronic module to lose spark, and when checking it subsequently with a spark neon it showed weak and intermittent spark.
I'll have a go at replacing that earth braid, but I'll also drop the ignition switch contacts off for a clean. Hopefully that will fix it...
1970 95 V4 van
1972 Sonett 3
1973 95 V4 estate | |
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| Topic | |
Intermittent ignition cut out
