that was why i was confused when you mentioned the 2 things.

althought it might look straight forward, i am betting it is not 😄 

3 minutes ago, froggy8 said:

that was why i was confused when you mentioned the 2 things.

althought it might look straight forward, i am betting it is not 😄 

Yes, I should've kept quiet in this case. 🤐 

Ok I had to go somewhere that is 25 miles away so went on motorway and the battery light didn't come on once but when I went off the motorway going at 30, the light came back on. So I thought I would do a few tests. I was driving on the dual carriageway slowly speeding up, when it went just past 40 miles per hour, the light went off.  I did this test about 4 times and it went off everytime I got past just 40. 

My theory is the brushes in the alternator is sticking so by going fast enough, it sort of freed itself?

What do you guys think?

oh and when it went below 40 then the light came back on again makin gme think it got stuck again?

What rpms is the engine pulling at 40mph?

You should be able to replicate the issue revving the engine while at a standstill to see if it is rpm related. Or if it’s that the alternator is breaking down as it warms up and the airflow travelling at speed is enough to cool it down. 
 

Myself I’d get a replacement - some places will take your old one in px to be reconditioned etc. Let them worry about what has or hasn’t failed inside it. 

I have already bought another one and I have no clue how to fix the alternator but I do like to know what is the causes when things breaks. 

I didn't see what rpm I was doing unfortunately 

40 minutes ago, froggy8 said:

I do like to know what is the causes when things breaks.

It could be something as simple as needing new Carbon Brushes or the faulty Diode Pack or Regulator but you will probably never know.

When I started driving nearly all British built cars had Lucas Alternators and you could buy all the spare parts for them cheaply at most Motor Factors or scavenge parts from old Alternators but I doubt that spares are now available to joe public.  

4 minutes ago, Tizer said:

nearly all British built cars had Lucas Alternators and you could buy all the spare parts for them cheaply at most Motor

Yes indeed, back in the day I have repaired/refurbished many of the Lucas ACR alternators fitted to Escort's, Capri's (the real one) and Cortina.

Your local motor factors may supply exchange refurbished alternators.

These can be preferable as they are rebuilt originals rather than copies. They will normally charge a deposit that can be refunded when you give in your failed unit.

The old unit will then go back to be refurbished by the supplier.

That’s the route I went down when my original alternator failed a few winters ago. 
 

Sadly the remanufactured Ford part failed after a month or so and I had to go the hassle of getting it tested, it passed, refitted, still no good, removed & replaced etc all in the middle of a snowy winter and the return of covid too. Which meant getting help for refitting the belt was tricky ☹️

A 'refurb' is only as good as the person doing it and the parts they're using.  Only original part left is the casing.  Not really any different to buying an aftermarket part.

1 hour ago, TomsFocus said:

Only original part left is the casing

I very much doubt a refurb would include replacement of the stator and its windings or the rotor unless there was unrepairable damage. At most it would be a strip and clean, test of rectifier stacks and regulator, examine for bad solder joints etc., clean up of slip rings, new brushes and new bearings.

8 minutes ago, mjt said:

I very much doubt a refurb would include replacement of the stator and its windings or the rotor unless there was unrepairable damage. At most it would be a strip and clean, test of rectifier stacks and regulator, examine for bad solder joints etc., clean up of slip rings, new brushes and new bearings.

Fair enough.  I also had a 'bad' refurb a few years ago.  The windings looked brand new, but perhaps they were just cleaned well.  Either way it didn't last long and I ended up replacing it with a good used one instead.

My car broke down about 2 miles from my home lastnight So I used my portable jump start and since the alternator has been working. Very strange, worked all last night and all day today.

47 minutes ago, froggy8 said:

My car broke down about 2 miles from my home lastnight So I used my portable jump start and since the alternator has been working. Very strange, worked all last night and all day today.

Sometimes when the Brushes in an Electrical Motor are well worn a kick start so to speak will allow it to operate for a period of time before giving up again.

ok guys

my alternator turned up lastnight but was bit late so il be doing this job in about 30 mins.

wish me luck! 😄 

ok guys

i have just replaced the alternator.

started the car up and measured the battery and it is at 14.40v so the laternator is working.

took it for a test drive and everything is working like it should 🙂 

apologies, forgot to thank all of you who helped 🙂 

just one more question please

i did another test with the heater on full, front window heater and back window heater then the high beam. it measured at 12.50 with the car running. please dont tell me this alternator is on its way out?

20 minutes ago, froggy8 said:

i did another test

Are there no pubs open near where you live ? 🤣

You trying to get me arrested? 😆😆