QuestionQUESTION: Howard you helped me immensely before and I hope again. I have two problems. The first is big.
While I was idling my car it just stopped running. I checked the spark and it had a weak to no spark from the coil. I replaced the coil and the car fired right up and ran better then it had since I had the engine rebuilt. (I have about 20 miles on the newly rebuilt engine and about 5/6 hours of idling while I work on it).
I thought the problem was fixed. I took the car out for a spin and the car died again. Again, no spark. I tried to get it to work and even went so far as to hot wire the car. I had twelve volts to the + side of coil but I tried to hot wire it anyway. I still did not get a spark (sometimes a very weak spark). I had the car towed home and put in the garage. Since the coil was new I thought I might need a new resistor (that attaches to the Neg term of the coil).
I could not find a resistor so I bought a replacement coil that had “internal resistor” printed on it. I bought that coil. When I got home I tried to start the engine before replacing the coil and the car started!!! I did not change anything and it started.
So, I figured the coil is not bad. I put the old/original coil back in and it started!! So I don’t think it is the coil.
The points, condenser, cap, rotor, wires are all new. The engine is timed and the points are gapped well and the car runs fine.
What would make it stop running but then start after cooling down (I hate to say after cooling down because I just ran the car for an hour and it did not stop running)?
One more note: When the car stalled the first time, the car would not start from the ignition key. I had to use a remote started on the started to get it to start. The two are likely related but, I have an old starter relay that I jiggle around to make the car start by the ignition key. I am ready to replace the relay but I have been holding off because it costs about $115 and keep thinking I can fix it.
As a further troubleshoot, I disconnected all the wires to the starter relay and the car kept running so I don’t think the problem with the car stopping spark is from that relay.
Thoughts on this?
The second question is I seem to be leaking oil from where the distributor goes into the engine. There are no gaskets I can see of where the two come together and I don’t see any in the parts manuals. Is this typical? Should I just make a gasket?
Help and thanks in advance!!
ANSWER: Hi Robert,
You need to measure the resistance of the primary windings of the coil. (+) to (-) (wires disconnected)
If it is 2 to 3 ohms, you should not use a resistor. If it is 1 to 2 ohms you need a resistor. If you use a resistor, you need to check the wiring. The resistor must be in series with the coil (power from "Key On" to the resistor and from resistor to the coil) (Be sure the polarity of the coil matches what ever you have on the battery/batteries. You never said what year "B" this is. If it is (+) ground battery then the points side of the coil must be (+) If it is (-) ground battery, you must have the coil (-) to the points.
If you are using a 1 to 2 ohm coil and a resistor you need to test the power wires to see that the power wire that bypasses the resistor is connected directly to the coil only when the key is in the "Start" position.
The reason a resistor and a low ohm coil is used is because when the starter is used, there is no longer 12v available to the coil. So they have a wire that is only powered when the starter is active and it supplies power directly to the coil and bypasses the resistor. When the car starts and the key is released back to the "Run" position the first power wire goes dead and another power wire powers up the resistor to the coil. If it is wired wrong and you run direct voltage to a 1 ohm coil, it will over heat the coil and stop running.
You need to do these tests. let me know the results.
As far as oil leaks at the distributor, the distributor has an
"O" ring seal on the lower part to seal it.
Howard
---------- FOLLOW-UP ----------
QUESTION: Howard, I did some testing. I have three coils. Two are new and one is old. When I measure the resistance from the positive to negative terminals on the coils each of them show zero resistance! Of the two new ones, one has printed on in "Use with external resistor" and the other says "Use without external resistor." Both of those measure zero resistance. I am pretty sure the ohm meter works. The car is a 1975 B with negative ground. What I thought was a resistor is a device (a Type SV 1uF 150 Volt DC WKC) that was connected to the positive side of the coil to ground. I is not an in-line resistor. I get no reading when I try to test ohms from the wire the to metal base. I am not sure what this is.
Negative side of terminal goes to the distributor.
I have two wires that go to the positive side of the coil. One is hot with 12 volts all the time whether the key is fully turned or just in the on position. The other wire is dead all the time no matter the position of the key.
Does the starter relay play into this problem? It is faulty and I will eventually replace it. If the coil issue is related to the starter relay I will replace now.
Thoughts?
AnswerRobert, you can't skip important things and think you are going to diagnosis a problem. The chances of finding three coils that all have dead shorts between the two posts is out of sight. Your ohm meter is either no good or you have it set on the wrong scale.
Since I am older than dirt and have been fixing cars probably before you were born please humor me by following my directions.
The device you found is small and looks like a condenser with only one wire, right? The marking "1 uf" is usually put on capacitors (condensers) and added to a coil for radio noise suppression. Throw it away. A ballast resistor has two connections at least and is usually 2 to 3 inches long and they usually mount on the coil. Some MG models had a resistor wire and thus didn't require a ballast resistor on the coil. What year and model MG is this?
You need a ohm meter that has a low ohm scale and you should have a 12v test light also. I learned a long time ago to forget what may be the problem and to use a systematic method of diagnosis. I am always surprised what I find but I always find the problem.
Let me know when you have a low ohm scale ohm meter and a 12v test light and tell me the year and model of the MG.
Howard
