Ignition coil question on my 1983 W123 2.0

[gassygassy]

I saw on another thread that a loose screw on a wiring terminal block near the coil was causing cut-outs so I dismantled mine, cleaned all the wiring O rings and reassembled them with copper grease. My terminal block screws were not loose but i decided to remove and clean the O rings anyway. They were a bit dirty but looked basically OK but the earth may have been intermittent, I couldn't be sure. The car has run fine since. But then it most often did run fine before I did that. Time will tell . . . .

 

[gassygassy]

I have found the fault. If anyone is still interested, the fault was a badly built aftermarket fuel pump. I did the "I haven't changed that bit yet, maybe it is that bit so I'll change it" routine. A new fuel pump - that is to say Another new fuel pump fixed the problem. I cut open the old new fuel pump and could see what was wrong. There are two circular rubber valves that allow fuel to flow one way. One of them had not been seated properly and was flapping about a bit.
Reminds me of 1972 when my Mini broke down on a country road a mile out of town. I diagnosed the ignition coil to be faulty, walked to town and back with the new coil, fitted it, it still wouldn't start. I walked to town and back with new points. Not that either. Walked to town and back with new condenser. Not that either. Walked to town and back with new ignition leads. Not that either. Having lost all sense of what the fault could be I walked to town and back with new spark plugs. Eventually late in the day I walked to town and back with a second new coil and it burst into life. So my original diagnosis was right, and the first new coil was faulty. It's amazing how your logic disappears out the window when you are confused - why didn't I test the coil by holding its HT lead against the block and see if there was a spark? But having said that, with my Merc, the fault was intermittent so you can't really do anything except change out parts till the fault goes away.

 

[190]

Reminds me of 1972 when my Mini broke down on a country road a mile out of town. I diagnosed the ignition coil to be faulty, walked to town and back with the new coil, fitted it, it still wouldn't start. I walked to town and back with new points. Not that either. Walked to town and back with new condenser. Not that either. Walked to town and back with new ignition leads. Not that either. Having lost all sense of what the fault could be I walked to town and back with new spark plugs. Eventually late in the day I walked to town and back with a second new coil and it burst into life. So my original diagnosis was right, and the first new coil was faulty. It's amazing how your logic disappears out the window when you are confused -

My simplest bit of diagnosis ever was back in 1976 with a brand new car only weeks old and the engine just stopped dead one evening when I was out with the girl friend (now wife). This was bog standard points ignition so the first step was to remove the distributor cap and check out the points. I got the young lady to crank the engine to see if the points were opening and closing and was surprised to see the cam not rotating at all. The distributor drive had sheared and the car was going no where that night except on to the back of a recovery truck.

Still have points ignition now on my 79 BMW motorcycle and it has the original 45 year old coils and what I think is the original set of points. They don't wear out because I fitted a points ignition booster that I built from a kit when the bike had only done a few thousand miles so the points contacts are only switching mA at low voltage. Even the points heel hasn't worn much as it's kept lubed. I keep thinking I should replace stuff but if it isn't broke, don't try and fix it.