theestimator Posted June 17, 2016 Report Share Posted June 17, 2016 Mk 2 Vitesse fitted with an alternator and when engine starts the ignition light dims but does not extinguish but with headlights on ignition light gets dimmer but still not extinguised. New alternator fitted two months ago but someone suggested that I need a bigger crankshaft pulley but unable to find advice on what size or if that is the problem and if not would be able to steer me in right direction. Flat battery every 2/3 weeks and this has a;so be renewed Thanks Gordon 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 17, 2016 Report Share Posted June 17, 2016 Sounds like a diode has failed in the alternator regulator the orig crank pulley works fine on most , and changing that only changes the cut in speedrevs thats not you problem this could also be your battery problem as there can be permanent discharge 24/7 if you have a multimeter you can ring the diodes out thers one passing current both ways pete Link to comment Share on other sites More sharing options...
Clive Posted June 18, 2016 Report Share Posted June 18, 2016 I would be returning the alternator.... However, how was the dynamo control box "sorted" to suit an alternator? A picture or accurate description would be helpful. (you MUST rewire the control box to suit an alternator) Pulley size is a red herring. 1 Link to comment Share on other sites More sharing options...
theestimator Posted June 18, 2016 Author Report Share Posted June 18, 2016 Clive and Pete Thanks for your replies - and thanks for advice re pulley. Ref the battery have tried other batteries and still have the problem Ref the control box - check under dash sometime ago and the black control box is no longer in place but a pile of wires - did have a problem with engine not starting but was traced to a bad ignition joint which has been repaired. Will try the diodes of the alternator but as usual when you buy new you expect them to work so that is why I discounted the alternator Thanks again and will try diodes later today as have a car show tomorrow Gordon Link to comment Share on other sites More sharing options...
JohnD Posted June 18, 2016 Report Share Posted June 18, 2016 theestimator, Suggest you live up to your nom d'Internet and do some measuring! What volts are available AT the alternator when running? Should between 14 and 15V. If low or high, then there may be an alternator fault, but as you say, that you be unlikely with a new one. "Pile of wires" where the Volts Regulator used to be? Shouldn't be. This MG site explains how to convert from dynamo to alternator, and basicly, it's connectinfg the right wires where the VR box used to be, not a tangle. My bet is, poor engine block earth. However much the alternator puts out, it has to return. Triumph provided a manky length of wire mesh, often rusted away or forgotten when an engine is put back in. Use a length of the same cable used for the starter motor - it has to carry that current too - from the block to a really, really good earth. The battery earth is best. John 1 Link to comment Share on other sites More sharing options...
theestimator Posted June 18, 2016 Author Report Share Posted June 18, 2016 John Thanks for that and will check earth connections on Monday as got car show tomorrow but taking fully charged battery with me incase of problems - not electrical minded so all help given will be acted on. Thanks gordon Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 18, 2016 Report Share Posted June 18, 2016 Battery solution to alternator disharge is disconnect it when parked up. small bulb jumped between batery lead and battery post , if it lights you have discharge cheack all is switched off, pull plug on alternator if light goes out , then alternator needs to follow pete Link to comment Share on other sites More sharing options...
JohnD Posted June 18, 2016 Report Share Posted June 18, 2016 Gordon, I left out a link to a conversion website (there are many) that shows the minimal reconnections that such a conversions needs - not a "pile"! And please, electrical minded or not, buy yourself a multimeter! Less than £10. John 1 Link to comment Share on other sites More sharing options...
theestimator Posted June 21, 2016 Author Report Share Posted June 21, 2016 John Thanks for all your info and yes will buy a multimeter - just to put into the mix when following previous advice I touched the low voltage line from the dizzy to the coil and it came away in my hand so have repaired it and that seems to have made a difference as last sat went 50 + miles for car show and no problems but as I have stated I HATE electrics on a car - will still check out all advice given and thanks to all you guys for advice Gordon Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 21, 2016 Report Share Posted June 21, 2016 I dont feel any connection between warning light and dizzy lead but if its cured thats a plus pete Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now