Battery, Alternator, or Regulator?

Question

After fitting my radiator to my 94 2.0L Nissan Primera, I drove round the block a few times, fine. I drove to and from work yesterday fine, I drove my mom to and from her sisters house in the freezing cold yesterday fine, I drove to and from Tesco's yesterday, fine.

I drive to McDonalds today enroute to work, the radio was cutting out. Never done that before. So I turn down the radio and turn off the heated rear window. OK.

Try to start up at McDonalds, and the bloody thing won't start. I had to call out for a jumpstart from work.

Im now a little worried I either need a new battery or a new alternator since when the hose blasted off from my radiator, it drenched the alternator in a lot of liquid. But it's been fine ever since... for... well... a few days at least.

My car has done this before, but usually after I've run it for 10 seconds then tried to start it again the following day... I can't figure it out... I mean, it can't be the cold as it was warmer today than yesterday, could it be a a slow but excessive discharge?

I'll be getting my multimeter to it, but Im not holding out much hope that I'll actually find the problem. But being familiar with how water has affected the alternator on my Datsun Cherry, Im thinking it could be the regulator...

Any opinions gratefully received.

Cheers Simon

Dave Plowman (News) · Accepted Answer

Your DVM will show whether the alternator is charging or not. Expect tosee something between 13.8 - 14.4 with the engine at a fast idle andnothing switched on.

david.cawkwell · Answer

Start the car.With the engine idling switch everything electrial you have on. Youshould hear the engine load as it has to drive the alternator around.If not the alternator is not producing enough juice.An AA man said that on some cars the brushes on the alternator canstick which means it might charge sometimes. Hence your problem. He hitmy one with a hammer to see if itcured it.

adder1969 · Answer

...or do the headlight test - start the car, put the headlights on, switch off the car - the lights should dim.

If you charge the battery on a charger and the car is ok again for a few days then it's more than likely the alternator. If it won't stay charged for long then it's probably the battery but could still be the alternator as well.

Simon Dean · Answer

Well I got my jump start... and I've been outside on the hour every hour at work starting the car... starts like a charm... wasn't listening out for any extra engine load though.

But everything seems fine again. But I will get the multimeter out and try the headlight and other electrical loading tests later tonight.

I know I left the car for two and a half weeks while I was unable to drive and everything was fine, so I might discount the battery. But I can use the car happily for weeks, months at a time and everythings fine.

The lights on the dash though have been a little dim recently... But that's about it. But how can one jump start instantly cure everything for such a long period of time?

Cya Simon

Battery, Alternator, or Regulator?

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