Author Topic: Battery or alternator  (Read 2270 times)

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Offline Pristle

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Battery or alternator
« on: October 20, 2016, 01:45:05 pm »
Had a weird issue yesterday. Travelling at ~95kph on the Southern Motorway, past Rainbow's End, the tranny changed down to 3rd for about 2 seconds and then back into 4th. A bit concerned I tapped back to 80 for the rest of the journey to Papakura. No more issue.

Get off the motorway and head west, pull off from 1st set of lights, no problem. Pull off from 2nd set, tranny wouldn't change up beyond 2nd. Slowed and slipped it in and out of neutral, still 2nd. Pulled up to the side of the road, slipped it into neutral when the car died. With the signs experienced when the battery died a while ago.

Got the car towed home. Suspecting the tranny, this morning plugged in the diagnostics which reported "Supply Voltage B+......intermittent". This pointed me towards battery or maybe alternator.

Using a booster cables, I was able to turn the engine and start the car. However when detaching it, the car ran for about 3-4 minutes before dying. As long as there's an external source, she runs.

Battery is a Bosch unit which is still showing it's 'green eye'. Am I right in assuming the alternator, even if the charge light had not come on?

Offline black16v

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  • paul
Re: Battery or alternator
« Reply #1 on: October 20, 2016, 09:54:12 pm »
Sounds like a charing fault. Faulty alternator? Wiring fault to alternator? Fan belt, loose or missing. Don't trust the green eye in the battery. I have seen faulty and flat batteries show a green eye.
1988 MK II GTI 16V

Offline Pristle

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Re: Battery or alternator
« Reply #2 on: October 22, 2016, 05:40:31 pm »
With a little time to myself earlier I tested the alternator in situ. No output. Pulled it, stripped it and found why, the brushes have almost been worn down to nubs, just failing to touch the commutators.

Missed getting to Platinum today, so popped along to Zebra in Onehunga. All sorted. Still awaiting the 'green eye' to return, so will be wary for a short while.

I just need her to keep going until January.


While the Golf has been out of service, I've been using a Kia Sorento (http://www.trademe.co.nz/motors/used-cars/kia/auction-1157495560.htm) that belongs to a client. They kindly lent it to me whilst they've been relocating and I've used it to ferry visiting software guys and some of their IT kit. I was pleasantly surprised what a good machine it is. Turbo diesel, that has averaged 7.9l/100 carting 3 adults about town and country (plus yesterday afternoon's southbound traffic ~50minutes of virtual idling).

He is selling it and is likely open to reasonable offers. I'd consider it if I was in the market for a 5/7 seater.



Offline black16v

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  • paul
Re: Battery or alternator
« Reply #3 on: October 25, 2016, 05:43:54 pm »
It will take a life time for your alternator to charge the battery until the green eye has returned. You really need to charge it with a smart charger (c-tek or similar). A trick our battery rep showed us was turn the battery upside down a couple of times, be careful that acid doesn't came out of the vent, and the green eye returned. Calcium batteries can get "stratification" if not charged correctly, the acid at the bottom of the battery is stronger than at the top and this can erode the bottom of the plates.

Don't underestimate the Korean car industry they are making some good cars.
1988 MK II GTI 16V

Offline Gordo

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Re: Battery or alternator
« Reply #4 on: October 25, 2016, 11:10:11 pm »
If the battery has been run down for a while, not fully charging, it may never take a full charge again.
Give it a try but don't be surprised if you have to buy a new one.
These are my thoughts and opinions - sometimes I'm wrong, but not often ;-)