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Another car, another problem

I have just taken possession of a Minor 1000. It started first time and I drove home (about 10 miles) with no problems at all. I switched off the engine to use the keys to lock the boot, then started it up to park it a bit more tidily.

It started first time, I drove forward about 4 feet and the engine cut out. It wouldn't restart, though just occasionally one cylinder fired, which was just enough to throw the starter bendix out of engagement.

A look under the bonnet showed good quality HT leads, new(ish) distributor cap with a free-moving carbon brush, new points, new rotor arm, new condenser. So clue: it has happened before, and someone has done something about it. No loose wires on the coil or distributor either. Nevertheless, it refused to start.

I left it while I got on with something else. A couple of hours later, I tried it again. It started first time and ran perfectly.

Obviously, it is something that resets itself when the engine cools down. My gut instinct says it is a dodgy coil, but the only way to diagnose the problem properly is to check things systematically.

However, there is a limit to how many times I want to go on a 10 mile run in the hope of reproducing the fault, whilst praying it doesn't leave me by the roadside miles from anywhere waiting for it to cool down enough to restart.

So has anybody had a fault like this before, and if so what caused it?

Jim

Reply to
Jim Warren
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There are some notoriously dodgy pattern rotor arms out there.

Ian

Reply to
Ian

Had exactly that fault many many years ago on a Honda motorbike - coil failed when it got hot. A particular pain because the coil was inside the pressed steel chassis, underneath the petrol tank - so by the time you'd got the bike dismantled to check the problem it'd cooled down again and was working fine !

FWIW there's a Minor owner's group over on Yahoo groups - called morris_motors - but, if 'everything else' has been changed then swapping out the coil would be a cheap experiment...

..alternatively ask the question over on the Yahoo group - somebody out there might have been there and done that...

Good luck with the Minor - running a '64 Mog traveller here as day-to-day transport - so far been pretty reliable (said he, touching wood frantically!)

Adrian - West Cork, Ireland

Reply to
Adrian

Top posting cause its long -

First check the point gap (015"), if as you say looks like new leads/cap etc. Points may have worn off a dag and closed up.

r

Reply to
Jimmy

Check the fuel pump. They're notorious. See if it's delivering fuel. Usually cleaning up the contacts in the pump solves the problem.

Reply to
Chris Bolus

That was the first thing I checked. It ticked once when I turned the ignition on, and there was a smell of unburnt petrol from the tailpipe when I had wound the engine over for a while. It is not a fuel fault, I am sure.

Jim

Reply to
Jim Warren

I fitted a halfords rotor arm and cap to a rangie that I was fettling for LPG and after a few weeks it ran crap and wouldn't run while hot but was fine while cool, tried everything bar the rotor and cap.

I was convinced it was fuel or coil etc.

In the end, I took the cap off. Bingo, inside of cap was chewed up as was the carbon contact. Rotor was pretty eaten too. Partco one cured that.

Reply to
Elder

The cap and carbon brush are in good nick. The rotor arm looks new and undamaged, but I haven't taken it off to see what the makers name is (if it is actually shown). Buying another one just in case wouldn't break the bank though.

Jim

Reply to
Jim Warren

Worth changing it just to make sure and if no change keep one as a spare anyway. On the MG bulletin board there are many tales of poor rotor arms which break down and track internally to the dizzy shaft.

Reply to
David Billington

Hows the point gap?

Reply to
Jimmy

Hows the point gap?

Reply to
Jimmy

Did the coil feel very hot?

If so, it's possible that someone has fitted a modern coil, designed to work with a ballast resistor. They soon get a bit warm with 12v across them...

Reply to
Kevin Poole

The coil is mounted on top of the dynamo and behind the radiator, so although it did feel hot, I put that down to the location. It could be a 6V coil working without a ballast resistor though. I hadn't thought of that.

I have ordered another one. It will be interesting to find out whether it runs cooler.

Thanks for the suggestion.

Jim

Reply to
Jim Warren

A hairdrier on the coil might show up a heat related thingie.

However, I'd be inclined to check carefully all the work done. If you have a spare condenser try that too - they can be intermittent.

Reply to
Dave Plowman (News)

That should be obvious by inspection, though?

Reply to
Dave Plowman (News)

Very close inspection as they may be breaking down and arcing through the plastic rather than over the surface, doesn't leave much of a trace internally.

Reply to
David Billington

The coil did feel hot when it wouldn't start - but when I took it off earlier today and checked the markings, it was definitely not the ballast resistor type.

I have now fitted a new coil, and checked the rotor arm, which is perfect, but has no maker's name, and the points gap is a generous 15 thou, but less than 20 thou. It will probably be the weekend before I get time to take it on a long run, but I did describe the symptoms to Charlie Ware and he said it was characteristic of a failing coil. So the new coil should have fixed it.

Thanks for all the helpful suggestions.

Jim

Reply to
Jim Warren

Back to the drawing board... I took the car for a run - it started first time and drove perfectly. I eventually stopped at a shop, and when I went back to it a few minutes later, it wouldn't start. Again.

So I wandered off, and came back nearly 2 hours later and it started first time. But when I put it in gear ready to drive off, the engine died. And didn't restart in the couple of tries.

So, a chance to do a bit of diagnostics. I put the starting handle in, took the HT lead running from the coil to the distributor off at the distributor end, held it near a cylinder head nut and turned the handle. A nice fat spark! I put it back on the distributor, turned the starting handle to line it up to remove it - and the engine started. And I drove home. No problems, no misfires, it drove normally, and I parked it.

So I switched off the engine, counted 20, switched it back on - and it wouldn't start. I put a multimeter across the coil LT and it showed battery voltage then 0V alternately as I wound the starting handle. Again the HT lead from the coil gave a good spark. I tried No 1 cylinder HT lead which is the shrouded type, and got a nice jolt up my arm at the appropriate time.

Yet still it wouldn't go. While I was doing all this, the petrol pump ticked occasionally, so I know the pump points aren't corroded.

So now the electrics show no faults, the spark is generous, proving that there can't be much wrong with the condenser or points, and it is a brand new coil. And when the engine starts, it runs normally which indicates the plugs are OK, it is just that sometimes (when the engine is hot) it won't start.

Have I missed anything on the electrics side? If not, then the problem has to be fuel - either a vacuum in the tank, a blocked petrol pipe or a dodgy needle valve are the next to be eliminated. Unless anyone has a better idea?

Jim

Reply to
Jim Warren

Vapour Lock in the fuel line?

Stuart H.

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Reply to
Stuart H.

Just as a suggestion, this happens to my MG. I only drive it infrequently, the batteries are not charged very well, it will start when cold, I can drive it some distance etc and when I stop, can't restart the motor, will turn over on the starter but not enough the fire the spark.(hills and a push start help after that), Have found that there is not enough power in the batteries to do both, turn the motor over and fire the ignition, placing the car on charge fixes the problem.

So my questions are:

Is the battery in good condition??

And have you tried a push start??

You may want to check the fan belt and charge rate as well.

r
Reply to
Rob

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