Strange fault

[Alan D.]

Hello all,

My brother in law Peter is going to look at a Mk 3 convertible, with a view to purchasing the car. But it has this fault. Below is a copy of the email sent to myself.

Hi Alan
The fault is when starting it some times starts ok. But you can try starting the engine turns over but then there is a clunk ,and it feels like its trying to go backwards and does not start.The starter has been stripped and is ok .Query flywheel ring gear teeth missing? Could it be a starter motor problem. Have you any other ideas?. Please, or could you ask if someone with greater experience of the Midas or specifically the A+ 1275 engine if they have any ideas what it could be.

kind regards
Peter

Can anyone through any light on this problem.

Regards Alan

[DavidL]

The flywheel ring gear would probably be my first thought, too. Can't think what else it could be, if the starter seems ok - I assume the starter gear is moving freely?

[Moneypit]

It's my Midas we're talking about here. It's not a ' clunk' as such, nothing hard up against anything. It's more like a pre-ignition, a feeling ...if that makes any sense!It will turn over then a sort of choked chug!?? Almost like low battery.
I've stripped the carb, replaced the rotor arm and ignition/amplifier module on the side of the dizzy. I've stripped the startor motor...it was mucky inside but the brushes are a good length and it works fine on a bench test.It's a pre-engaged type starter and all appears to work well with the solenoid.The solenoid by itself though, can rattle in and out when volts across it, so I was thinking possibly poor contacts under the plunger.Also brand new, fully charged battery.
I put a coil on it from my sprint engined Latham. It's a cold start coil ( does this man it should be in a ballast resistor ignition and so only run off 9volts?) and the car starts 8 times out of 10. I put the new coil back on and problems again.I presume the metro system is not a ballasted one as there is supposed to be (and is )12volts at the +ve coil terminal when the ignition is on.If so ,I also presume that this is why I'm getting a better spark with the 'cold start 'coil even though this will probably kill it.
I'm still hoping it's the starter motor taking too much juice but don't have a spare to try. I was hoping to use two batteries, one for the starter and one for the solenoid and ignition.If this works, it will at least show it as ignition problem rather than anything else.
As for the ring gear....i've had the engine spinning without the ht lead connected and it spins fine with no symptoms.

[DavidL]

It's so long since I worked on an A series and its ignition system that I don't remember the ins and outs of a ballast resistor setup.
However, what I do remember is that my donor Metro's system was indeed a ballast system, the coil was a 6v one which in normal running gets its 6v via the ballast resistor. When the starter is engaged, the ballast resistor is bypassed because using the starter position in the ignition switch does two relevant things; supplies power to the starter and also supplies the coil direct from 12v.

It may have been 9v, not 6v, I'm not sure. However, if the coil is permanently supplied with 12v rather than the 6v or 9v it needs, the points will melt and close up. I discovered this only during my Bronze's first trip to try to get it taxed. Since yours is electronic ignition I don't know what would happen.

I read your post again... sounds like your Midas is not a ballasted system if there's 12v at the coil with the ignition in the "running normally" position. That may be because of the electronic ignition, but I'd imagine that if "cold start coil" is synonymous with "ballast resistor fed coil", then it wouldn't do the coil much good in the long term. What voltage does the Latham have at the coil?

[Moneypit]

The Latham is not in a state where the voltage can be checked but from what I've read I believe it to be 6volts at the coil. I'm thinking this is why I'm getting a decent spark on the Midas all be it to the possible early demise of the coil if it were in permanent use.

[DavidL]

Is there a solenoid on the Latham you could substitute?

Three times now I've been about to post a suggestion about how to test if the solenoid is the problem, but it's a procedure which will make a big spark and wouldn't pass any Health & Safety guidelines, so I've deleted it each time before posting.

[Moneypit]

Unfortunately the Sprint starter is completely different to the Metro. Can't use the solenoid as both 'piggy back' the starter.
Just put the new coil on and starts. If the 'chugg' symptom occurs (for want of a better expression), the lights go very dim as would occur with flat battery so still suspect starter but have no spare to try.

[DavidL]

Another thought - is the battery under the bonnet or in the boot? Sounds similar to a problem I had with my Bronze, which had the battery in the back of the car. If I stalled the car when it was hot, the starter would only turn over very slowly, yet cold starts were fine. I changed everything - starter, solenoid, even tried another battery, but I think the problem was that effectively, the battery was twice as far away from the starter than it was in a Mini, and I think I should have used thicker battery cables...

It does sound like something taking a lot more current than it should, though.

[manifold]

To run 2 battery cables in the boot you must use 32mm2 cable otherwise the voltage drop is too great. 32mm resistance is equivalent to a steel car body.

Could be a bad connection in the cable somewhere on the connections to solenoid...ground cable to block etc.