Hi,
The alternator in my Series 4 gave up so the easiest thing to do was find a series 5 alternator and wire it in, I followed the wiring diagram exactly and it all went to plan, however a week later the lights all came back up on the dash and it only seems to charge intermittently.

So it will charge for 20 minutes or so, and then it'll stop working again. there's a crackling noise under the dash that appears just before it dies, but I'm yet to find the problem.

Any ideas, or should I be taking it to a professional.

The belts seem loose but the alternator is at the extent of it's adjustment, I'm considering changing the Adjuster to a slightly longer one, as I couldn't fit original belts over the new dual sheathe pulley my alternator came with.

 

Get the alternator tested.
The belt should be tight when it is on the car and not allow slippage.
OH,take the battery and get it tested too.Sometimes when the alternator gives up the battery will work so hard that it gets Cooked too.
People just replace the alternator and not think about what the battery has been through.

 

Definitely check the battery. I replaced 2 alternators before finding a good working one. With it installed and driven for 4 hours, I pounder why my battery wasn't charging. As it sat over night, my battery would drain down to 8 volts. Had it tested at autozone and it turned out bad. I dropped in another battery and its been running fine for 2 days now.

Pick up a multimeter as well.

 

Turns out it was indeed the belts being to big, went on size smaller and it's working a charm, cheers all.

 

side question. how functional is the dual alt pully? is it mostly for looks of is it worth the money and extra belt noise?

 

I've not noticed much difference in the pulley functionallity wise, and the noise is not noticeable as I previously had Gilmore pulleys on until the alternator I had broke the Belt and pulley. Apparently they prevent water slosh or something similar.

In my mind it just makes sense to have a spare belt incase one breaks already on the pulley to keep everything running

 

I never thought about it being a fail safe for the water pump, sounds like a sound investment! thank you for the information!

 

actually if you had an airpump on and deleted it,then went with a 2 belt alternator,you wouldn't have any more belt noise than what you started with.
I've had stock,Gilmer and 2 belt configurations.
I like the 2 belt.It assures me that even if one breaks the other one is there.Then again why would just one break?..hmm?