TR674 Posted August 9, 2007 Report Share Posted August 9, 2007 Hello all, I've just joined this forum. I have a 1974 TR6 PI with overdrive (apparently assembled by Leyland in NSW). I have the original Lucas alternator installed which I had serviced/reconditioned by a specialist British car auto electrician (endangered species) many years ago. Over the last few years of daily driving I have experienced problems with the alternator over working and melting the diode. It's been replaced 3 times now. I have no spot lights or heavy amp draw items, just an added cd player (min draw on amps). I cannot find a short of fault in the electrics, does anyone have any suggestions on what may be going on here? I don't want to upgrade to the Bosch 55amp alternator without finding out what is causing the alternator to work so hard. I noticed that after a 20 minute drive home yesterday, the alternator body was very hot to the touch, is this normal? Any help would be appreciated, as I'm not very good with electrics. Regards Craig Quote Link to post Share on other sites
JohnC Posted August 9, 2007 Report Share Posted August 9, 2007 Could a dodgy ammeter be your problem? I've just had my alternator replaced with a 65A Taiwanese copy of the original Lucas. When I picked up the car the electrician warned me that there's a voltage drop somewhere between the alternator & the battery, and that this will cause the alternator to fail prematurely. He didn't go into details, just encouraged me to fix it or get him or another electrician to fix it. He suggested that the ammeter may be the culprit, saying that they do sometimes develop increased resistance over time. I'm no electrician, but perhaps this is worth investigating. Cheers, John Quote Link to post Share on other sites
TR674 Posted August 9, 2007 Author Report Share Posted August 9, 2007 John late model TR6's have the ammeter replaced with a volt meter. Volts show 13.5 normally, but with lights on and at idle volts read 11. Above 1000 rpm with lights on it reads 12.5 (not to say the guage is correct). How much was the 65a alternator worth? Regards Craig Quote Link to post Share on other sites
JohnC Posted August 9, 2007 Report Share Posted August 9, 2007 Johnlate model TR6's have the ammeter replaced with a volt meter. Volts show 13.5 normally, but with lights on and at idle volts read 11. Above 1000 rpm with lights on it reads 12.5 (not to say the guage is correct). How much was the 65a alternator worth? Regards Craig I guess it's not your ammeter then! 12.5V sounds like discharge to me - the alternator puts out something like 13.5V - so something (or a combination of somethings) is drawing more than your alternator can generate. By way of comparison, I've just checked my car, and here are the voltages across the battery terminals: 1000rpm (no lights) 14.2V 1000rpm (lights on dipped beam) 14.0V I think you need to do a little digging. Something may be getting hot somewhere. How is the earth strap? As for the alternator, it was seriously not cheap. $260 including fitting (over £100 to those in UK). Incidentally, my autosparky suggested fitting a voltmeter in place of the suspect ammeter. Any chance you (or somebody else) could post a pic of the original fitment? There was one went on eBay a few days ago, but I wasn't sure if it was the right style - red and green arc, rather than the black & white I was expecting. Cheers, John Quote Link to post Share on other sites
stuart Posted August 9, 2007 Report Share Posted August 9, 2007 I guess it's not your ammeter then! 12.5V sounds like discharge to me - the alternator puts out something like 13.5V - so something (or a combination of somethings) is drawing more than your alternator can generate. By way of comparison, I've just checked my car, and here are the voltages across the battery terminals:1000rpm (no lights) 14.2V 1000rpm (lights on dipped beam) 14.0V I think you need to do a little digging. Something may be getting hot somewhere. How is the earth strap? As for the alternator, it was seriously not cheap. $260 including fitting (over £100 to those in UK). Incidentally, my autosparky suggested fitting a voltmeter in place of the suspect ammeter. Any chance you (or somebody else) could post a pic of the original fitment? There was one went on eBay a few days ago, but I wasn't sure if it was the right style - red and green arc, rather than the black & white I was expecting. Cheers, John If its any help the voltmeter fitted to Scimitars is the one to get as it looks correct with a change of the chrome bezel for your original 6 black one. I did this conversion to a 250 not long ago. Stuart. Quote Link to post Share on other sites
JohnC Posted August 9, 2007 Report Share Posted August 9, 2007 Thanks Stuart - do you have a picture of the voltmeter please? Cheers, John Quote Link to post Share on other sites
jonlar Posted August 10, 2007 Report Share Posted August 10, 2007 Hi Craig and John, I don't know how much shipping would be to Oz, but it may be worth asking this guy http://cgi.ebay.co.uk/LUCAS-18-ACR-ALTERNA...1QQcmdZViewItem I bought a couple of re-con alts back along £20 for the pair +£15 P&P. Quote Link to post Share on other sites
stuart Posted August 10, 2007 Report Share Posted August 10, 2007 Thanks Stuart - do you have a picture of the voltmeter please?Cheers, John Unfortunately not of the gauge the only one of the dash is attached and is taken too far away to see properly, but if you PM Caveman on this forum its his car that I fitted it to and he currently has it for sale. It is of the downward pointing pointer Smiths type with the same type of face as the ammeter but shows volts from 10-15/16. Stuart. Quote Link to post Share on other sites
JohnC Posted August 11, 2007 Report Share Posted August 11, 2007 Thanks Stuart, that's what I needed. Downward pointing, battery symbol, black & red arc. Cheers, John Quote Link to post Share on other sites
Guest ron Posted August 12, 2007 Report Share Posted August 12, 2007 John, There's one just posted on Ebay 320147255023. Ron PS Not mine by the way. Quote Link to post Share on other sites
JohnC Posted August 12, 2007 Report Share Posted August 12, 2007 Thanks Ron - upward pointing unfortunately. All my other gauges point down, so that's what I'll try to find. Cheers, John Quote Link to post Share on other sites
Guest ron Posted August 13, 2007 Report Share Posted August 13, 2007 John, I had a Smith's voltmeter with the needle pointing down the way as an accessory gauge in my MGB years ago so they are available. Ron Quote Link to post Share on other sites
JohnC Posted August 13, 2007 Report Share Posted August 13, 2007 Thanks Ron, Yes they are even available brand new from Speedy Cables, complete with the correct bezel, but at a price - over £40 delivered to Oz. I'm hoping to snaffle one on eBay for a bit less. Still, it's good to know the new ones are still around. Cheers, John Quote Link to post Share on other sites
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