Lotus Elan

Ignition coil failures - is it just me?

PostPost by: nigelrbfurness » Fri Apr 14, 2017 7:09 pm

I'm just canvassing opinions here. I know there are modern alternatives but all my Lotuses and other classic cars have always run pretty reliably on conventional points and coil ignition systems, as long as they are maintained properly. However, over the last five years or so I've noticed that my S4 likes to eat up ignition coils. I always use non-ballasted coils now. Years ago I tried using ballasted coils and found they didn't produce a strong spark over 6000rpm so went back to non-ballasted. That could just be a red herring.

Where once upon a time a coil lasted for years and years and thousands of miles, I'm now getting typically 2-3000 miles out of a coil - ie about the frequency of my oil changes! I've just had another one fail today. Having been caught out in the past, I now keep a brand new replacement in the boot, along with points, condenser, cap and leads and mount the coil so its easily accessible without removing the engine :)

I buy my ignition parts generally from Moss Europe and all my coils have come from there for the last few years. Points and condensers, I bought about 50 sets ten years ago from a motor factor who was selling up so I just change them when needed.

So what is it with my coils? Are they just crap these days, compared with when all cars used them? Or could there be some underlying fault that's causing them to fail so frequently? I will add that my Healey Sprite has eaten a fair few in the last five years too. So I'm erring towards the "crap" theory. However, I am prepared to be educated by those that are coil experts... :D

Anyone have an opinion as to what might cause frequent coil failures?

Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: gjz30075 » Fri Apr 14, 2017 9:26 pm

Heat and/or vibration usually is what kills a coil.

Have you been buying the same brand over and over?
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PostPost by: nigelrbfurness » Fri Apr 14, 2017 9:47 pm

There is certainly plenty of heat and vibration under my Elan bonnet :D

I guess it is a harsher environment than most 1960s and 1970s cars. My AH Sprite isn't hot under the bonnet though and the coil is firmly supported on the body and yet they don't seem to last much longer either.

Perhaps finding somewhere better to mount the coil on my S4 would prolong the coil's life though. At the moment its mounted on the bonnet support bracket stay. The original coil from years ago is still in the well under the carbs, because it is totally inaccessible!

Maybe in front of the radiator somewhere, in the airflow might help.

Brand-wise, it is whatever Moss have for Minis, MGBs, Spitfires etc. probably from India. I don't think there were any markings on the one I just took off. It was black rather than aluminium coloured though. I remember buying three at the same time...
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: Quart Meg Miles » Fri Apr 14, 2017 10:22 pm

Have you checked the voltage supplying it once the revs rise, perhaps your regulator has failed? Is the original "inaccessible" coil still a working one that you could use? I'm not sure I've ever had a coil fail (in its original position) though I did change it many years ago when tracing a misfire which was actually a rich mixture.

I would change your supplier if the voltage is correct, 3000 mile life is ridiculous. I take it the car runs OK with them otherwise.
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PostPost by: gjz30075 » Fri Apr 14, 2017 11:56 pm

Quart Meg Miles wrote: I'm not sure I've ever had a coil fail (in its original position) though I did change it many years ago when tracing a misfire which was actually a rich mixture.



Nor have I. My Lucas Sport coil, in the oem position, has been fine for many years. I suggest
starting with a brand name coil.
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PostPost by: Craven » Sat Apr 15, 2017 12:09 am

Older coils were oil filled, now a solid insulation is used, a poly-something I expect, Maybe the latest technology is not best. Heat dissipation!
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PostPost by: prezoom » Sat Apr 15, 2017 2:49 am

My gold sports coil from Moss has been on my car for 11 years with no problems. Knock on wood.
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PostPost by: RogerFrench » Sat Apr 15, 2017 4:42 am

Are you sure that when your ignition is off, you don't have some strange voltage through the coil? Being permanently "on" can really shorten its life.
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PostPost by: nigelrbfurness » Sat Apr 15, 2017 8:36 am

Thank you for all your suggestions. The car often sits for several weeks without use and always starts well so I doubt there is a permanent voltage on the coil but I'll check it anyway.

The original coil did fail hence the reason for replacement, that was about 25 years ago as I recall. I left it there and fitted the replacement in the position it is in now. I didn't really start to have these problems until around five years ago and its had three coils in the last five years, maybe replaced it once in the intervening 20 years but to be honest memory is not what it was.

The first warning of imminent of coil failure is usually a momentary wild display on the rev counter at highish rpm which then settles down again for a while, followed by increased popping of the exhaust on the overrun, followed by a tendency to die at wide throttle openings. Within a few miles it usually shuts down completely and fails to restart, though sometimes it will be fine for a bit once the engine has cooled down.

That's just for interest, I doubt its related to the real problem.

Reading back through your replies, I'm inclined to think putting the coil back in the original position might be a good plan, though if it fails getting at it means removing the K&N air filters which is difficult at the side of the road.

I think first off I will buy a branded replacement and see how we get on.

Thanks again to all who took the trouble to comment.

Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: bob_rich » Sat Apr 15, 2017 8:41 am

Hi Nigel

Are your coils of the metal cased oil filled type ? If you shake the coil you should hear the oil slop around.
If it is oil filled it may pay to mount the coil High Voltage (HV) nose down so the oil insulation fully surrounds the HV output connection. Also if it is a metal cased unit make sure to firmly ground the metal body to the engine block. this will ensure a good return path for capacitive currents that may flow. Also make sure the SW and CB terminals are not swapped.

All of the above are very minor points and in general would not be expected to cause a major problem that effect life - - but you never know

What is the resistance of the coil you use ? and have you cut open a duff coil to see if you can see what the problem is ?

Hope this helps best of luck

Bob
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PostPost by: lotusfan » Sat Apr 15, 2017 5:35 pm

Nigel

When I rebuilt my Sprint I did some research on coils and found a website that said that the Bosch coil was the very best. Burton is one of the places that sell them -

http://www.burtonpower.com/bosch-blue-h ... 19027.html

These are more expensive than the unbranded e-bay ones but you do get what you pay for. I have them in 2 cars and neither has missed a beat since they were fitted.

HTH
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PostPost by: nigelrbfurness » Sat Apr 15, 2017 9:33 pm

Hi Bob
I will confess I've never cut one open, that might be interesting to do when I have the time! As far as I know they are just bog-standard coils which once upon a time you could buy in Halfords or any motor factors, I assume they are oil filled. It is unlikely that the connections are incorrect as I'm usually pretty particular about that aspect of car electrics but again, it never hurts to check these things!

The coil is actually currently (ouch!) mounted with the connections pointing downwards at an angle. In the original position the coil is mounted with the terminals uppermost and other contributors are claiming long coil lives with them so mounted, so perhaps it doesn't make a heap of difference - the coil on my Sprite in in the factory position and its virtually horizontal. All puzzling.

Thanks very much though for your input :)

Mike:
Thanks for the link tot he Burton coil, that sounds like its worth following up. I shall order one and hope that it solves the problem!

Nigel F.
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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PostPost by: fatboyoz » Sun Apr 16, 2017 6:24 am

Nigel,
The Distributor Doctor sells Pertonix brand coils. They can be found under the Electronic Ignition tab.
http://www.distributordoctor.com/lucas- ... ition.html

Cheers,
Colin.
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PostPost by: martinbrowning » Mon Apr 17, 2017 9:38 am

Nigel, My vote also goes to The Distributor Doctor - I get all my points, condensers, rotor arms etc from them and never have a problem - not the cheapest but top quality. Martin Jay, who runs the small company is a very knowledgeable guy who shares our passion for classic cars - he has several of his own and thinking of buying an Elan so can't be all bad.
He was featured recently in the "Specialist series" of articles in "Classic and Sportscar".

No connection with the Company etc, just a very happy customer.

Martin B
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72 Europa Special, 72 Sprint, 72 Plus 2
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PostPost by: Andy8421 » Mon Apr 17, 2017 10:18 am

Indeed. Martin was very helpful when I was rebuilding a distributor from a pre-war Standard.

I started using DD products after a series of failed rotor arms had me being towed back to the pits on a regular basis. No problems since using the 'red rotors'.

No connection with DD, and I would highly recommend him. Its people like this that deserve our support.
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