Alternator on the out?

Technical Area Engine, Transmission, Exhaust etc
2

Hi guys,

Im just after a little advice, last night driving some from work my Mk1 conked out on me twice at low revs. At the time I thought it could have been a fuel pressure issue…not that there was a splutter or anything I was just very low of fuel :stuck_out_tongue:

I managed to get fuelled up, got her home without any more issues though I did sit a traffic light holding higher revs when I had to stop. I sat on the drive when I was at home. The car was idling and reving ok so I went inside feeling it was likely to do with Fuel.

So a few hours later, after the engine had cooled, my curiosity got the better of me so I went and started the car. Started straight away per usual, I let the idle settle, revved her a couple of times, no issue. Switched the side light on to light the instrument panel, no issue. When I asked the the headlights, everything dimmed considerably, the idle started to move a little but when I blipped the throttle the was a horrible squeal from the engine bay.

I went under the bonnet and revved the engine and the horrible squeeling and sqraunching sound was definately coming from the front the of the engine. Alternator and belt are probably on the out right?

My question is though, surely the alternator is working all the time to charge the battery? Turning the lights on doesnt add load to the alternator does it?

If I can get home before it gets dark I will attempt to get a vid of the situation just for clarification!

Cheers for the help in advance!

 

3

The squeal you heard will be the alternator belt slipping, so that needs tightening.  No reason to assume the alternator is faulty.  It may be your battery is low, perhaps just due to the cold weather.

Yes, any electrical load you turn on adds load to the alternator so makes the belt more likely to slip.

4

I had an issue with a MK2 where a belt in good condition snapped.  On inspection I found that one of the four long steel bolts that hold the alternator casings together had corroded and split the aluminium casing.  This caused the bearing that holds the armature to lose centrality and the armature was touching the field coil in one area.  Over time the pulley seized and belt snapped.

Check alternator for damage and also pulley for play or binding.  Check belt tension and then run the engine.  Make sure that the battery is reading around 14.5 - 15 volts when the car running - this proves that the alternator is working properly.      

5

Just a quick update,

I mananged to get out to the car and check the alternator belt tension, it was remarkably slack. After a bit of swearing and a couple of dropped sockets I managed to tension it up and (so far) i’ve not seen any of the offending issues!

Thanks very much for the advice, I was pretty ready to spend £150 on a new alternator, now I’m just going to replace the belts next time I get some time!

Cheers Folk!