Ok. I've got the dreaded alt light beaming at me now. Started with a light 'pulsing' and is now staying on even at speed. Did the search through some posts and have seen some talk about fan belt slip which can be either from a worn belt or worn pulley. Alt brushes are fine. So... should I be able to rotate the fan by hand in neutral without the belt moving? Does this tell me the belt is kaput? Just wanted a sanity check before progressing. Thanks. Evan.

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You should not be able to rotate the alternator pulley.
Check the tension on the belt and failing that fit a new belt.

If the alternator is spinning at all with the engine when it is running, the light should be off, pretty much no matter how loose the belt is.

You might need to have the alternator serviced and/or check the alternator terminals as well as the connections at the solenoid.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Is the pulley / fan on the alternator tight on the shaft?

I would say yes , i can with mine , but it's firm . How old is your belt ?

With your engine , you should have to push a fair bit of pressure on the belt to make the engine roll over , you don't need a sh!tload of tension on the belt to excite the alternator .

What Alternator are you running on your car Evan , early 15 AC with ext reg , or later clubby , 17 AC type , Int reg ?

With a multi - meter , have you tested for voltage at the battery? , that should tell if it's
charging or not .

The light on mine was glowing dimly after I put the 1360 engine back in. Has done this a bit from time to time.
I found the spade lug on the thick brown wire (12V+ output from alternator) had a hot joint so I chopped it off, crimped a new one on then soldered it for good measure.
Light is now off.
Check your connections there.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

+1

The point I was making earlier is that the belt would need to be cut off to make the light come on while the engine is running.

The light is a result of a automatic detection inside the alternator of current flowing to the battery. If the light is on, then there is no charge from the alternator. If the belt is on the pulley, then there will be charge from the alternator. It just slips under high load, it doesn't affect the light.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I am too used to generators. Of course you blokes are right.
If it was going slowly flat without the light coming on it could be the belt slipping.

Rotate your fuses and clean up the fuse terminals. My clubby ignition light used to come on from time to time because there was not enough tension on the small spring arms in the fuse holder to make a good contact.
Worth a try.
New fuse box from KC fixed that.

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Now with 2 extra ports!

Went for a quick run yesterday. Battery was dead flat so I hooked up the jumper leads to see if the battery would take hold charge after a quick run. Got to Stockton, red light all a glow and total shutdown. This tells me that there was not even enough charge to run the fuel pump right?

Was rescued, left jumper leads on for 5 mins and bam, straight back to life. Barney has also been running like a dog in the last few weeks, a bit spluttery with gurgling and popping running against compression. With a bit of charge in the battery, it seemed to not miss a beat.

So, does this mean the battery is stuffed (not getting regular use anymore) or the alternator is stuffed and not sending any charge back to the battery. I've checked all the terminals and the belt seems to be OK.

As an aside... Minispares have 16/17 ACR alternators for 40 parnds, which would be cheaper and quicker than stuffing round with an auto electrician?

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http://www.rylstoneclassic.com

Sounds like the alternator to me, not the battery.
You can also get new Lucas alternators here from Karcraft, `convertible mini' in Brissy, and Minisport in Adelaide.

There's not much stops an alternator though- I've found it's always just the brushes, or the V regulator, or a bad connection.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

When the alternator light pulsates on and off it is in most cases the Brushes worn. Slip rings are never perfectly round or flat so as the Alternator turns brushes make contact in one spot but not the next which cause the light to switch on and off. Get the Alternator brushes checked. I should have my new stock of 70Amp Alternators in a few days.

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Thanks for the input all.

Convertible... How much are your 70amps?

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http://www.rylstoneclassic.com

So, I've wrestled with Barney for the last few nights. Tried to replace the brushes in-situ, but the retaining screws were a mongrel (were in fact tiny hex-head bolts about with the heads only about 1mm deep).

Whipped the alternator off today, new brushes installed.

All the while, I've had the battery on trickle charge, but I needed jumper cables to bring him back to life. Let it idle with the choke a few minutes and a few throttle blasts to clear his throat. All looking like a victory at this point.

But, Alt light still pulsing on and off. No pattern to it. Moreso at low revs.

I then went and did about 10 laps of the new estate here at Fern Bay and the light went off. I figured, maybe the brushes are bedding in?

Got home, pulled into the drive, Barney still wants to stall and the red light is mocking me. I shut down and figured I see if I had any charge. Nope. Dead. Simply a whir of the ignition winding down and final yelp from the alarm siren.

So, is my battery stuffed or could it be that the alternator is not sending charge back, despite the new brushes?

Probably a really simple thing, but it seems am I.

Evan

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http://www.rylstoneclassic.com

Perhaps a diode has gone short circuit, and it's discharging your battery..
Or, the V reg is cactus.
Time for a new alternator, saves stuffing about.

Karcraft has 45A ones for under $120. (bigger than you have now).
70A ones are a bit more.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.