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MG MGA - Another exploding coil

Had a nice run out in the spring sunshine today, about a 60 mile round trip. Parked up in the garage, went in the house for about a minute and then returned to the car to check the fluids etc. As I walked into the garage I noticed a strange smell, popped the bonnet to find that the coil had exploded (see picture) and discharged its oil in the engine compartment and on the floor. Prior to this, the car had been running perfectly, and it appears that the coil didn't explode until after I had stopped the engine, as there was no oil outside the garage where I had stopped to open the door. This one appears in the archive a few times, but the questions are, what causes it, is it a faulty coil and what is the solution?


Lindsay Sampford

I see it is mounted on the dynamo. Later they moved to the body - less heat and vibration? But of course should not cause this. What current is / was it taking?
Art Pearse

Can't remember Art, but it was a new Lucas Sport Coil last May and I checked the resistance of the primary coil when I first got it and it measured up to the specifications given on Barney's site. Ignition system is a bog standard mechanical points set up. Points gap is spot on and prior to this happening, the engine was running as sweet as a nut. At least it got me home before it failed!
Lindsay Sampford

Is your generator pushing out the correct voltage Lindsay? Voltage regulator problem?
Also is your coil a 12v coil or a 6v without a ballast resistor?
Cant think of any other reasons for the failure apart from a bad batch of lucas sports coils
Cheers
Colyn
Colyn Firth

Same thing happened to my brand new Lucas DLB105 Sport coil last spring Lindsay. The replacement has been working for a year now but I'm going to keep my spare (old) coil in the boot just in case. I'm suspicious of a bad batch of coils as well. The coil that exploded on me has a sticker on the bottom that says 'DLB 105 Tested 09/08'. Any similar markings on yours?

Andy Bounsall

Lindsay,

About 18 months ago I had a brand new Lucas Sport coil fail. It didn't blow like yours, it just leaked out the cooling oil and fried. I wasn't as lucky as you were, mine failed at speed on the freeway.

Moss replaced it without a question, but I am now carrying an old Lucas coil as backup. The body material of the Sport coil seems to be much thinner than the older Lucas coils. I am inclined to buy a Pertronics coil on my next order, $40 is not worth the aggravation of breaking down again.

John
jjb Backman

Andy, similar to yours, mine has a sticker that says 'DLB105 TESTED 11/08'.
Lindsay Sampford

Hi Lindsay,

Treat yourself to an epoxy-filled pertronix Ignitor!
These days I get the impression that Lucas=Lottery.

Regards

Malcolm
Malcolm Eades

But that's just a replacement for the points Malcolm, it's my coil that's blown up!
Just found the old Ducelier coil that was originally on the car when I got it, cleaned it up and resprayed it. Its body is made of steel, so let's see if that one will explode, it certainly would go with a bigger bang if it did!
Lindsay Sampford

Lindsay
I can't help thinking Art has it right - why not move the coil to a cool and vibration free mounting somewhere convenient on the body. On top of the dynamo must be one of the worst positions for a coil.
Good luck
Bruce.
Bruce Mayo

Bruce, my old ZA Magnette had the coil mounted on the dynamo and I had no trouble with it in 25 years (most of them as a daily driver), so I think it could down to poor quality modern components. If there had been an issue with the dynamo mounted ignition coil, would BMC have moved it back there for the De-luxe models when it had been mounted elsewhere on the 1600s?
Lindsay Sampford

BM perhaps that's why the Mk2 coil is on the side and lower than the dynamo on its own separate bracket off the engine mount (see Clausager p64). This is a less exposed position. A simple change to make.
J H Cole

Lindsay

Clearing out my garage (sale agreed). I have a spare smoke recharging canister if you are interested.

Steve
Steve Gyles

Lindsay
I have the Pertronix Electronic ignition which is a complete replacement distributor (No points ). It looks virtually identical to the original and it is paired with a Pertronix "Flamethrower coil" ( I know, silly name). It works well, I have noticed much better starting and tickover with it too, even 2 years on.
I believe the timing curve is better for the engine (mines a 1900 MGB 3 bearing ) and it also eliminates points bounce which gives better performance at higher revs.
I keep a standard dizzy with points and condenser plus a spare coil and ignition leads in the car just in case ( "belt and braces?") but so far I have never had to use them.
Colyn
Colyn Firth

Actually Lindsay, what are you doing with an upgrade part in your car? I thought you were all for originality - no 5-speed gear box etc!!

Lol

Steve
Steve Gyles

Lindsay,

Sorry, I wrote Ignitor when I meant Flamethrower, which is the coil that goes with their system.

Cheers

Malcolm
Malcolm Eades

I'm not so much for originality (I do have relays, extra fuses, halogen headlamps and 60 spoke wheels), more for an easy life Steve. I'd rather be driving it than wrenching the gearbox out!
Lindsay Sampford

This thread was discussed between 18/04/2010 and 20/04/2010

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.