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Failing Alternator?


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Hi all.

 

When I started the car this evening, I noticed the ignition light didn't go out - it dimmed, but still a faint glimmer. Also, volt meter was hovering around 13v instead of the usual 14v+

 

I drove for a mile of so without change so stopped to check connections at the alternator and battery. All seemed Ok and no squeals so assume fan belt not slipping.

 

Restarted and heard a gentle whine which appeared to be coming from alternator. Volt meter now down to 12v. Connected multimeter across battery....11.8v at tickover but only going to 12.5v when revving.

 

Assume altimeter on the way out but would appreciate any other thoughts/comments before I replace.

 

Thanks, Steve

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Hello Steve, my alternator failed a while back, and I replaced the diode pack and brushes. Trouble is, they are really poor quality, and failed again almost immediately. I wound up buying another alternator (TRshop, I think). It seems OK now. Austin

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I had this problem on the way to Spa in May… alternator failed and I had to fit a spare to complete the journey. Took the unit apart and the brushes fell out as one had broken. Fitted new brushes and regulator and the unit is now on the car and working again. You can get the rebuild kits on eBay for about £15.

 

Matt

Edited by matt george
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Sorry for the delay, I bought a new alternator from Auto Electrical Supplies.

 

Fitted this one:

 

https://www.autoelectricsupplies.co.uk/product/908

 

As they say this is the more expensive one but it has been great since.

 

Am sure the diodes would be a cheaper fix.

 

Snowy

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The Chap at the International was doing Refurbished 46A ones for £40.

Had one from him a few years ago lasted 50miles before rumbling bearings, had it rebuilt completely and the guy who rebuilt for me said it had only had a cheap Chinese regulator in it and that was all, bearings were all shot.

Stuart.

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Had one from him a few years ago lasted 50miles before rumbling bearings, had it rebuilt completely and the guy who rebuilt for me said it had only had a cheap Chinese regulator in it and that was all, bearings were all shot.

Stuart.

You learn by your Mistakes.
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If you have a backstreet auto electrics shop - the sort in yellow pages - that does starter and alternator repairs it could be worth checking out. Key Auto Electrics in Walton, Liverpool checked my alternator out for no charge, and instead of rebuilding it they supplied a Lucas high output for about £30 a few years ago

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The Brown Book suggests a Lucas 15 ACR (28A) was standard with an 18 (43A) or 17 (36A) for later US models.

 

I will see if I can work out what my current one is when I take it off (it doesn't look very old...) but is it safe to assume 36A or 43A would be a safe and easy option?

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I suspect this rating is fine. I have a 75 amp an have redone the main wiring plus a new junciton boc and feed for the fuel pump and fan.

 

I figured the lower 'standard' item is not going to run a Bosch fuel pump (mine consumes c 10 amps) and electric radiator fan and charge the battery at the same time.

 

If your wiring is good and you have a bosch fuel pump set up then i would use a 43amp. Lower if you have a lucas as they seem to run at lower amps for same pressure.

 

All this base done my experimenting - other views ?

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Struggling to find anyone locally who could look at a repair I've replaced it with this:

 

http://m.ebay.co.uk/itm/CLASSIC-CAR-ALTERNATOR-UPRATED-50amp-LUCAS-17ACR-18ACR-Type-MGB-Mini-TR7-Capri-/170947512610?epid=17003693197&hash=item27cd440922%3Ag%3ANIkAAOSwjVVVpNNK&_trkparms=pageci%253Ab9616cbc-8333-11e7-a28a-74dbd180688f%257Cparentrq%253Aefa87edd15d0aa4897d9dd02fff92d27%257Ciid%253A13

 

Appears to be exactly the same as the one I took off, went on without issue and the ignition light now going out!

 

The company said they hadn't sold one for a TR6 before so if it didn't fit they would take it back at no cost to me.

 

First proper test run this morning while the sun is shining. Happy days.

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