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MG MGA - Ignition problems

Usually I'm pretty good with ignion problems, but not this time.

To start, my car was running like a charm last week. Met up with a couple of cars from our club and we headed out to a members cottage about 90 miles away.

We didn't get very far and we got stuck in traffic (imagaine Saturday morning). The car got very hot and started to run rough. The traffic cleared and I figured the car would cool down and everything would be fine. Nope! We just got over the bridge (Montreal is on an Island) and it conked out. Nada, nothing , no spark.

$190 later it was safely home. had a beer to calm down, then proceeded to diagnose the problem. Derek's (up north) car is in my driveway, so I borrowed his distributor cap. Nada. Then I borrowed his rotor, and it fired right up. OK, so I cleaned up a spare that I have, put it in, and the car ran like a charm.

So brave I was that I headed to my cousins on Sunday about 50 miles away. I got to within a mile of her house, then cough , cough, it stalled.

This morning I put in a new rotor and distributor cap. Nada. Put back the old distributor cap and it fired right up. For about 3 minutes. Then nada. So I checked the firing order on the new cab. Put it in. It started perfectly, then stalled after 30 seconds.

So we towed it home. At least it wasn't $190.

Now there is no spark. from the spark plug lead, nor from the coil lead.

If I place a light on the negative side of the coil. It flashs as it should. which I think means the points are OK.

Tried grounding the light on the distributor. Still OK.

Almost everything is new. So I'm at a loss.

Help!


Mike

Mike

Coil or condenser. A coil can get hot and fail then cool and work before it fails completely. A backup dizzy and coil are good things to carry. At least carry points condenser rotor and coil.
R J Brown

I have had both coil and rotor failures giving me road problems like this. I can see where a cap could also aggrevate the coil as the voltage at the coil is dependent on the gap of the plugs plus the gap between the rotor and the cap inside terminals. More gap in the cap would cause higher voltage at the coil, and of course across the cap itself. To best save the rotor and the coil, keep the plugs set at .025". or maybe .032" no higher.

My new coil lasted less than 1000 miles. It failed progressively starting out misfiring when hot and wirking fine when cooled off. Eventually it just failed ouright. My rotor was a used part, very old may have been hand made by Joseph Lucas! It shorted out to the disty shaft. High voltage available to the center lead of the cap, no voltage on any of the 4 output HT leads. The one that replaced it was also a used part. I love living on the edge!

New coil, rotor and condenser, and gaping the plugs properly, should clear it up for another 10k miles or more.

Chuck
Chuck Schaefer

Sounds like the coil or possibly a bad connection on the low voltage wire that's disturbed by removing refitting the cap.

If you need an out of the box idea, I had a similar problem with a mini many years ago, turned out to be a small loose washer inside the distributer on the base plate, causing a short circuit when in a certain position.

Neil
Neil McGurk

This thread was discussed between 11/08/2007 and 12/08/2007

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