A question of alternators.... (and fusible links)

purp · Post by **purp** » Mon Sep 09, 2013 2:26 pm

Vehicle: 1990 "L" series (in the very popular at the time white).
Engine etc: EA82, Carb, no power steering.

A little while back, the L started to have the dash lights flicker at start up. This was followed shortly later by the battery not holding enough charge to run the car. At this point, some simple investigation found that the battery was receiving no charge. As I had a spare from a past parts car, the simple trouble shooting method of swapping the alternator and seeing what happened was taken. With the "new" alternator on and the battery receiving charge I washed by hands and had a beer.

Skip forward a week or two, and the car dies again. Same symptoms, no charge seems to be getting too the battery. I have a couple of ideas for what it might be...

(a) There is an intermittant issue between the alternator and the battery...
(b) The "new" alternator just happened to die in the first week on the car...
(c) There is a problem somewhere in system which has killed both alternators...
(d) ????????????

Anyone got any advice/suggestions/ridicule ? I intend to try and check voltage at the alternator itself to rule out a basic break in the circuit, but apart from that I'm really not sure.

Cheers!

On a related subject - while having a look at the fusible links to rule them out (they appear fine), I discovered that they have a rating about which I know nothing. Anyone got a link to info on what units the numbers written on the box are in? What the colours mean? Can you even buy them if they do blow?

steptoe · Post by **steptoe** » Mon Sep 09, 2013 5:36 pm

search purple dude , and you shall find electrical, new style fusible links

showthread.php?t=18205&highlight=fusible+links is the pretty comprehensive thread

got a multimeter to test your alternator output, battery as it stands, with engine not running. running, revs up a bit ??

Gannon · Post by **Gannon** » Mon Sep 09, 2013 7:02 pm

The sizes of the fusible link are either the wire diameter or the cross sectional area, I cant remember which. Either of these ratings can be converted to the amperage that the wires will either carry or melt at.

I havent got the FSM with me but there was quite an in depth thread about it. Some members have replaced the coloured fusible links with like coloured fuses, I advise against this as I calculated the wires are rated at less than the coloured fuses allow.

steptoe · Post by **steptoe** » Tue Sep 10, 2013 8:10 am

and they replaced like colour with like colour as someone asked an auto elec and that was the advice given.

I knew an idiot that asked a mchanic how tight the brake caliper bolt had to be after flipping it to replace the pads. Mechanics reply was "fingertight" . Idiot took it upon himself trained as a chef, to replace next set of pads and did bolt up fingertight despite 26Nm cast into the caliper ! He saved a few bucks, but then found himself back in mechanical shop coz the bolt fell out. Happened twice untl he worked it out

Public carrying vehicle being serviced by non qualified !!

purp · Post by **purp** » Sun Sep 15, 2013 8:28 pm

Thanks guys, hopefully I won't need a fusible link anytime soon.

On the subject of the alternator...

I put the multimeter on the positive terminal on the alternator itself, and it read ~+14v.

For a second I thought I had identified the problem, but then I checked the battery again, and found it was charging (~+14v with the engine running). So something intermittent is happening...

I hooked up the multimeter to the lighter socket so I could watch it while driving. About 1km into the drive to work on Sat and voltage reading drops back to just the battery (~+12.5v). So I'm thinking it might be a dodgy wire between alternator and battery... But then I find that every so often the voltage goes a little crazy - fluctuates between 0v and +14v occasionally even reading negative... So I'm thinking the regulator is in the process of dying. This seems to be confirmed by the fact that a hard rev seems to kick it back to charging (for a while each time).

I did have a helper...

steptoe · Post by **steptoe** » Sun Sep 15, 2013 8:45 pm

I think you can get the symptom you describe as the brushes wear, and got to their last reach the braided lead allows. I have had a few alternatoras that ran happy for ages on just providing 12V and not much more - was OK for starting next day, after day - but leave it to sit a few days or a week - needed a push or a charge.

purp · Post by **purp** » Tue Sep 17, 2013 8:33 am

Hmmmm, so, are the brushes a serviceable part? And if they are would they be cheaper then another second hand one from the wrecker?