Unusual Breakdown

[myoldjalopy]

Here's a little puzzle for you folks
On a recent drive, after about 20 miles, the engine started jerking and hesitating and I managed to get in a field gateway where it died. Thinking ignition problems I checked coil connections, HT leads etc. but found nothing wrong. On opening the dizzy I thought the points gap might be a little too wide, so adjusted it and was pleased to find the car started up immediately. I carried on to my destination and a couple of hours later returned to the car which started up and performed flawlessly all the way home until, within 200 yards of my garage, the engine started juddering and jerking again. I stopped and ran some emery paper through the points, re-checked the gap and she fired up again. I put her away in the garage and ordered a new set of points as, on both occasions, fiddling with them seemed to have cured the issue - and they were about six years old.
When I went to fit the new points, I was puzzled to find the old ones didn't look too bad but decided to fit the new ones anyway and also check the little LT wire and generally clean things up a bit. Then I noticed something small lying on the engine bay floor, just under the dizzy. Recognising what it was, I suddenly realised what the problem had been and that it was one not found in any repair manual!
So, just for fun, any ideas?

[philthehill]

The carbon rubbing rod which fits into the top of the distributer cap and or the spring which keeps the carbon rod pressed against the rotor arm.

[geoberni]

As it's just for fun.... A Gremlin.

Gremlin.jpg (284 KiB) Viewed 2080 times

[philthehill]

You can buy a manual for that.

[Myrtles Man]

Anything to do with the spring clips that hold the dizzy cover in place by any chance?

[geoberni]

I must admit, joking aside, I have to agree with Phil's choice of the Cap carbon centre,
I can't think of anything else that could remotely fit the scenario otherwise.
And I can only assume it fell out completely after you got home.

[oliver90owner]

The only other alternative I can think of is a loose screw holding down the condenser and the condenser loosing its earth contact. Points usually get burned quite quickly if the condenser goes open circuit.

Another after-thought. The return spring for the vacuum advance mechanism - but vey unlikely and it wouldn’t give the reported symptoms - unless it pinked under heavy load

[simmitc]

A mouse or similar small rodent?

[ampwhu]

this is exactly why i changed to electronic ignition around 12 years ago. My dizzy cap has been off around 4 or maybe 5 times in that time. The car is 100% reliable and i would drive it anywhere knowing i won't have all this hassle.

If i breakdown i call the breakdown company. thats why i pay them a modest amount every year. why would i want to start fiddling around with the car in my sunday best / rain / nagging woman in the car with me. i can get it towed home and i can fix the problem in my nice warm garage. Too old for all that lying in the road at my age.

[les]

That’s told us !

[ampwhu]

That’s told us !

It's not supposed to come across like that. It's my opinion only.

[myoldjalopy]

Thanks for your replies folks. I can assure Mr. Ampwhu that I didn't have to lie in the road (just bend over the wing) and, indeed, it was not a fault with the dizzy as such. I will admit that the problem was a result of slight clumsiness on my part when I last fitted a new set of points about six years ago and I'm very surprised it took all that time to manifest as an issue! Any more ideas? I will put the record straight by close of play tomorrow

[paul 300358]

The plastic insulator that goes on the top and bottom of the points spring?

[simmitc]

Or the nut that holds the insulators in place.

[myoldjalopy]

Or the nut that holds the insulators in place.

No - but you are thinking along the right lines!

[Flywheel]

A wild guess but, what about the insulating fibre washer that fits over the points pivot post?

Would something like that cause an intermittent fault?

[paul 300358]

The small screw that holds the earthing cable from the points onto the distributor body?

[MCYorks]

If i breakdown i call the breakdown company. thats why i pay them a modest amount every year. why would i want to start fiddling around with the car in my sunday best / rain / nagging woman in the car with me. i can get it towed home and i can fix the problem in my nice warm garage.

Personal preference I suppose. It depends how long you have to wait for recovery and if you have a nice warm garage to return to
If I can fix a problem in 10 mins, then I'd prefer to do that rather than potentially wait 2 hours or more for recovery.

this is exactly why i changed to electronic ignition around 12 years ago. My dizzy cap has been off around 4 or maybe 5 times in that time. The car is 100% reliable and i would drive it anywhere knowing i won't have all this hassle.

I've fitted electronic ignition, which has its advantages, but still take the dizzy cap off every 6 months to clean it and oil the advance mechanism. At least the Minor dizzy cap has spring clips and is easy to remove. My 'modern' had a dizzy cap held with screws, which seized and snapped when I tried to remove them. That was a load of hassle

[myoldjalopy]

Oops - site has been down again!

Anyway, thanks for the additional, interesting suggestions. As I said, a case not to be found in any manuals or text-books.

What happened was, in replacing the points about six years ago, in the road outside my house, I mislaid/lost the flat washer under the screw holding the contacts plate down.So I hastily substituted a suitable replacement washer and the engine has run perfectly ever since - until the recent breakdowns.

The lost washer must have slipped into the distributor when I removed the screw and, somehow, remained in a harmless position for the next 16/17,000 miles until it recently vibrated out into a place where it interfered with the spark distribution. When I stopped the first time, it must have once again settled to a harmless position, only to jiggle out and cause further problems after another 25 miles or so. On removing the dizzy cap at the second breakdown, or when I later went to re-fit the points, it must have fallen out onto the engine bay floor where its surprise appearance led me to surmise what had happened. Problem solved! Although I'm surprised the washer was in there so long without causing problems. What are the chances of that happening?

All good now for the last 120 miles - and I'm glad I didn't have to call breakdown either

[ampwhu]

it does make me wonder why people pay for breakdown recovery when they want to attempt to fix a car by the roadside? why pay for a service you have no intention of using? never understood that. if it came with your insurance, fair enough but i'd be asking for a discount if it meant you wasn't going to use it.

it's like paying for gym membership in January for the year and then giving it up in February...........