Welcome to our resource for MG Car Information.
Triumph TR6 - troubleshooting alternators
|RECENTLY PURCHASED A 73 TR6. I NOTICED THAT THE voltmeter DOESN'T MOVE TOWARD CHARGE AT ANY TIME AND BATTERY EVENTUALLY RUNS DOWN. I'M A LITTLE RUSTY ON TROUBLESHOOTING ALTERNATORS BUT DID DETERMINE THAT THIS IS A THREE WIRE LUCAS. THE TWO LARGER BROWN WIRES ARE ALWAYS 12 VOLTS POSITIVE. THE SMALLER BR/GR WIRE DOES RUN TO THE IGN. LAMP WHICH NEVER LIGHTS UNLESS I UNPLUG THE BR/GR WIRE FROM THE ALTERNATOR AND GROUND THAT WIRE. I THINK THE ALTERNATOR IS BAD BUT DON'T WANT TO BUY A NEW ON UNLESS I HAVE TO. I HAD THE BATTERY TESTED, ITS GOOD. CAN ANYONE ADVISE ME AS TO THE ABOVE? THANKS MIKE|
|Maybe the simplest way is to take it to the auto parts place or auto electric shop. Most do tests free.|
|While your at it check out having it rebuilt....I had my starter rebuilt 2 years ago for less than a hundred.|
Hook up the volt meter to the battery. It should read around 12.5 to 13 volts. Crank the engine. During start the voltage should not drop below 9 volts. When the engine starts the voltage should rise to 13.5 to 14. This is the alternator recharging the battery after start. There are other checks but this is the simplest.
|Disconnect the battery while the car is running. If the car still runs, the alternator is good and the battery is bad. If the car dies, you've got a bad alternator and possibly a good battery.|
That was a common test to check alternators on older American cars. Lucas alternators are not known for being as robust. That proceedure will easily cause damage to the Lucas. In my experience a weak battery can kill off a Lucas pretty quickly.
It's best to do as others suggest and take the alternator in to a REPUTABLE auto electric shop/rebuilder. Many of the chain stores (Autozone, O'Reilly, Advance, etc.) don't have all of the adapters to connect up the Lucas. Although some of the chains offer lifetime warranty on a rebuilt unit. Don't know if that will apply here or not.
BTW - whenever a Lucas dies on me now, it gets replaced with one from a Saturn. I have one on my daily driver (MGB). It's gone a year and a half without a hiccup, plus it's keeping a 10 year old battery working as inteded.
|"That was a common test to check alternators on older American cars. Lucas alternators are not known for being as robust. That proceedure will easily cause damage to the Lucas."|
Good point Tom. I forgot how pathetic the original Lucas p.o.s. alternator was and how many heartaches it gave me. Since replacing mine with a 65 amp GM alternator, I have not had no problems. (Sorry you original guys).
If it means anything to you Mike, if you can't do a simple test of the alternator running your electricals because it may put to much sTrEsS on it, replace it with a more reliable alternator that won't give you the heartaches I had.
|I SENT THE ORIGINAL QUESTION. I APPRECIATE ALL THE INPUT. I WANTED TO TEST ALTERNATOR IN A MORE DECISIVE MANNER BECAUSE I'M KIND OF A DETAIL PERSON. ANYWAY PROBLEM IS SOLVED. I PICKED UP A REPLACEMENT ALTERNATOR AT A LOCAL TRIUMPH SHOP(THEY'RE STILL AROUND). IT CAME COMPLETE WITH THE FAN AND SHEAVE FOR 100.00. I INSTALLED IT AND IT WORKS. THANKS AGAIN.|
|Mike, I am weighing in kind of late on this one, but I did what you did. I got an alternator on sale from TRF for less than $100 and it fixed the problem. I don't think it is worth going to too much trouble repairing a 30+ year old thing when you can get a newly rebuilt one for that kind of money.|
This thread was discussed between 31/08/2006 and 06/09/2006
Triumph TR6 index
This thread is from the archive. The Live Triumph TR6 BBS is active now.