Distributor or just a duff coil?

Post by **youngb506** » Wed Dec 07, 2005 12:58 pm

Over the past couple of years my Minor's cut out suddenly for no apparent reason and then eventually started again. Sounds like the coil problem that others have had. Last night it cut out, the coil was quite warm, but still wouldn't start 5 hours later when I'd given up waiting for the AA to relay me home. The AA bloke seemed to think that there was up and down movement on the top plate in the distributor, ( the place the points are screwed to) that shouldn't be there and that it was causing a short which had burnt out the coil. Does anyone think this likely or is it just a bad coil? I replaced the coil about 4 years ago when the old one started leaking oil. Incidently, why so many coil problems? I driven Minors for 20 years and this never used to happen. Advice greatfully received since I like to use the car as often as poss.

Barry

Post by **Willie** » Wed Dec 07, 2005 3:50 pm

There is an interesting theory that modern coils do not contain as much of
the cooling oil as the original types had. This doesn't matter if the coil is
mounted in an upright position but does matter if the coil is mounted sideways
as on the Minor because the oil will not cover enough of the windings to keep
it cool so that it overheats and eventually fails. The instant pinpointing of your problem would be to carry a spare coil (make sure you buy a straight
12v unit) and fit it when the fault reappears. Your coil which, you think is the
culprit, should read approx 2.9ohms across the side contacts and 5.4 Kilohms
between the centre terminal and a side contact. Obviously,no reading on either means a dead coil.

Post by **Cam** » Thu Dec 08, 2005 9:05 am

Barry, for the reasons Willie states it would be a good idea to pick up some original type coils from autojumbles at Minor shows. Then you'll have some original oil filled types. They should last pretty much forever generally speaking. I have not had one fail personally, but I always carry a genuine known working unit as a spare just in case.

Post by **youngb506** » Thu Dec 08, 2005 4:02 pm

Thanks. I've heard of the mysterious coil problems. So, the movement in the top plate in the distributor is a red herring?
Barry

Post by **Willie** » Thu Dec 08, 2005 5:42 pm

BARRY.....yes, I think it is a red herring because the moving contact of the
points is totally isolated from the plate and only connects to chassis via the
fixed contact. i.e. when the points are closed the coil is full short to chassis
anyway and that is correct. Therefore even if some problem caused the
moving contact to go full short to chassis the result would be a complete loss
of a spark and a dead engine. If you left the ignition turned on with the engine 'dead' then you would burn out the coil eventually but this too is normal.

Post by **bmcecosse** » Sat Dec 17, 2005 10:21 pm

Poor old coil gets blamed all the time - but in reality they are very long-lasting. However - i have mounted mine vertically and off the engine with a longish HT lead to the dizzy. Look for poor connections/points burned - and most likely of all - condenser burned out. It's worthwhile re-newing all the ignition bits (not the coil!) every 2 or 3 years - cost is minimal and then know it's all new. Has the car never run since - or did the problem get fixed ? I assume it wasn't the fuel pump - which is the most common 'sudden stop' reason a Minor. Ignition problems usually show as poor starting /stuttering before they finally get so bad the engine fails completely.