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MG MGB Technical - Weird starting problem

Hello All,
Well it's getting close to what the UK calls summer here so I'm really looking forward to spend more hours than usual out on the road....
I've been using my MG, a 1972 18V engine mgb roadster fairly frequently over winter/spring and it went through it's MOT / service about a month ago with no problems electrical wise. My battery set up is 2 6V cells as per original spec.
So I used my MG over the weekend after it had sat for about a week, it started up fine and I did a 5 mile trip down the road to a hardware store. After 20 or so min came back to start the car, and after the initial click-click as the fuel pump got going, turned the key to start, and got what I can only describe as a rapid klack klack klack noise coming from the area of the starter moter. Great I though another new season another recon starter motor..., so called out roadside rescue, who after looking at the starter motor, checked connections, gave it a nudge with a soft mallet to see if anything was sticking or not engaging (I tried bump starting the car as well to try and engge as I've heard this can work as well if your starter motor is stuck). Nothing doing, same problem & same noise.
We checked the battery connections, all tight, then he used a power pack to jump start as if for a flat battery. You know what , fired straight up first time!, how could this be? the starter was turning over and I was'nt getting the same flat battery symptoms (we all know what those are with a classic car..)
I drove the car home, switched it off left it 5 min, turned the key and again, it fired up first time,

Any suggestions on cause and how to eliminate this problem will be much appreciated. It was suggested that I replace the alternator, which I know is at least a 5 year old recon with a new more powerful model (MG owners club does a 65amp model, any comments on this?). I checked the battery levels and they were up to correct levels. What would a hydrometer test prove here?
I dont want to have to drive around with my own power pack each time I go out.

Thanks all for any suggestions, have a great season!

Cheers
Steve Bennett,
S J Bennett

SJ, you didn't mention how old the batteries are. If it started right up with a jump maybe they are weak and coupled with a weak alternator perhaps it isn't charging enough to turn the engine over.
John

Despite how everything looks, I would be inclined to clean all the battery connections and the ground-to-frame connection. Moisture in these joints have gotten me a few times, not just in my MGs - and they are very easily overlooked.

Wayne
Wayne Pearson

Yep that's right WP. Check all battery connections, the link wire between each battery, the battery earth at both ends and the main starter cable both at the battery and at the solenoid on the motor. Then check the earth strap between the LH front engine mount and the chassis leg. Get the batteries tested by a good battery shop preferably LS UK and if they are down on capacity replace them with a single 12v battery Type 063. That's about it.
Iain MacKintosh

Steve

The rapid "klack, klack, klack" sounds that you describe are a classic sympton of a weak battery. The solenoid is closing and then dropping out as the voltage dips due to current draw - on dropping out, the current is cut off, the voltage rises and then the solenoid closes again and the cycle repeats.

This spring I installed my recharged battery and moved the car from winter storage. A short while later, on preparing to drive home, I had the same symptons that you described and called the CAA (equiv to AA or RAC in the UK)for a boost. As I had had the car almost 7 years, I immediately got a new battery and have had no problems since.

Regards,

Barry
73B
B.J. Quartermaine

If all the battery stuff doesn't pan out, have your starter tested to see how many amps it draws while cranking. It could have an internal short, but the battery problem is far more likely.

Jeff Schlemmer

Thanks All, for your comments and observations,
I'm replacing the alternator with a new 65 amp one, plus renewing my engine earthing strap, the batteries and connections at the battery end were done recently,
Happy motoring,
Cheers
Steve Bennett,
Steve B

Steve, why are you replacing the alternator ?? If the earthing is OK as you say and the batteries tested and are charged the alternator won't make one bit of difference.
Iain MacKintosh

This thread was discussed between 07/06/2005 and 09/06/2005

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