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Thread: Mk1b Alternator wanted

  1. #1
    MR2 Fan AndyB's Avatar
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    Lightbulb Mk1b Alternator wanted

    Hi all,

    I'm looking for a replacement 70 amp alternator. Mine doesn't seem to be up to the job anymore. I have the symptomatic "engine compartment cooling fan" and "Discharge" warning lights showing when the car is running.

    I can't spend too much as I've still not even got the car moving yet!!

    Thanks,

    Andy

  2. #2
    MR2 Fan julianw's Avatar
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    Hi Andy

    Fancy cutting your teeth on repairing an alternator? To expand, I had my alternator give up charging and very quickly got to the point where the battery was flat. The AA bloke I called out, took a hammer and piece of wood to the alternator body while the engine was running - "not too hard, mind! Too hard and you crack the alternator frame". Bingo, the charge light goes out and the battery starts getting juice. His explanation? The carbon brushes that contact the commutator (shiny copper strips you may be able to see through the gaps) wear down but get stuck in their channels, despite the springs behind them that are supposed to keep them pushed against the copper. The judicious tap he administered was enough to jolt them free and the springs pushed them back in contact with the commutator again. I opted to replace the alternator after this episode (I was reliant on the car as a daily drive), but I was tempted to follow his advice and just dig the old brushes out and replace them. I even took measurements of the carbon brushes that I would need to find/cut some bigger ones down to, to act as replacements. Shame I lost them when my last phone went bang. Can anyone provide the dimensions?

    Good luck
    Julian
    89 Mk1 N/A Mica blue Owned 2012-Present
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  3. #3
    MR2 Obsessive jimi's Avatar
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    There are other faults that can cause the "3 lights of death"
    Slightly more technical solutions than "hit it with a piece of wood" http://www.mr2oc.co.uk/know-your-2-k...d=3&kbartid=51 and http://www.mr2oc.co.uk/know-your-2-k...id=3&kbartid=3
    Last edited by jimi; 30th October 2014 at 05:45 AM.
    Black is not a colour ! .... Its the absence of colour

  4. #4
    MR2 Obsessive superwhite90's Avatar
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    I bought one for £125 and comes with a warranty of 1 year if you are interested i'll find you the details.

  5. #5
    MR2 Fan AndyB's Avatar
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    Quote Originally Posted by jimi View Post
    There are other faults that can cause the "3 lights of death"
    Slightly more technical solutions than "hit it with a piece of wood" http://www.mr2oc.co.uk/know-your-2-k...d=3&kbartid=51 and http://www.mr2oc.co.uk/know-your-2-k...id=3&kbartid=3
    Hi Jimi,

    Quick run through your diagnostics shows that I am getting battery voltage at the main connection but only on one of the 3 plug pin connections. Reading your how to article on mr2oc that infers that I have a fault int. wiring. I'm not sure how that makes me feel. I'm not the best at vehicle electrics but will take a look.

  6. #6
    MR2 Fan AndyB's Avatar
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    False alarm. Actually, I'm the king of false alarms what with my oil filter yesterday.

    Turns out I'd not read your article word for word and was testing with the ignition off. Both of the white leads in the plug are only live on ignition. One does read slightly lower 11.8v with the other side white lead reading 12.8v. So I'm back to thinking that it's th alternator at fault. Now where is that block of wood and my mallet..


    I'll save my big potential false alarm concern for later today..

  7. #7
    MR2 Fan AndyB's Avatar
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    @julianw. I also tried your "bash it with a big stick" trick but to no avail. Would have been funny (but quite handy) if this had worked.

  8. #8
    MR2 Fan julianw's Avatar
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    If you're imagining a scene like Fawlty Towers with the Austin 1100 ("Right, I warned you about this!") alas, it wasn't a case of flaying the bonnet with a willow branch with the leaves still on!

    Sent from my GT-S5830i using Tapatalk 2
    89 Mk1 N/A Mica blue Owned 2012-Present
    89 Mk1 N/A Superwhite Owned 2004-Present
    96 LDV Convoy minibus Red Owned 2008-Present
    98 V70 AWD Owned 2007 - 2010 RIP
    1990 VW LT35 Motorhome White Owned 2005-Present
    97 Escort estate 1.8TD Red Owned 2003-2004 RIP
    99 Multipla 1.6 Red Owned 2002-2003
    71 Austin Maxi 1750 N/A Dunghill green Owned 1985-1989

  9. #9
    MR2 Enthusiast Gilles27's Avatar
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    I will keep a hammer and lump of wood in my boot from now on!

  10. #10
    MR2 Fan AndyB's Avatar
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    Something to add to this thread. I'd seen mk1 alternators advertised at TCB for a decent price, and on calling spoke to a very nice, knowledgeable bloke. The alternators they have are all 1 type - the 60 Amp units, that I have read were the type fitted to the mk1a, with a 70 Amp unit fitted to the mk1b. The TCB guy said that the test sheet showed that it was labelled as 60 As but maxed out at about 70 amps at 6000 rpm. He said that they supply these to anybody with a mk1 and to was the first time he'd been questioned about 60 versus 70 amps. Should I be worried about fitting the 60A variant? It's a good price at about £112 + £12 postage.

    I'm also considering a local alternator rebuilder, who thinks it may be about £60/£65 to repair mine - has anybody gone down that route before?

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