car battery troubles!!!

[Anubis8]

hi there i have a 51 reg 1.9 tdi audi a3 130 sport.

this morning i tried to start it and the battery was dead and it wouldnt jump off another car. i charged the battery for a bit and it started. i took it for a drive and it was fine. it stood on the drive for 3 hours and when i went to go out in it, same problem. battery was completley dead.

any ideas? im stumped.

[deaconj999]

Hi,

I'm no expert but it sounds like the problem I am having with my 2001 1.9 tdi A3.

The battery light was on and the battery had been flat for a while. I jump started it and it worked fine for a few days. I then took it out and it started Ok. After returning from the shop I went to start it and it was dead so I had it jumped again.

After all that I bough a brand new battery and fitted ot myself as it is easy.

With the new battery the red battery dashboard light is still on so with a bit of research and a bit of testing with a multimeter I believe the alternator is not charging the battery. Check yours before you buy a new battery

So maybe your alternator is on its way out...... I am now looking for anew one.

[vwcabriolet1971]

A completely flat battery should be trickle charged overnight.
Check that the voltage at the battery terminals is at least 12.5V . A good charged battery should show 12.6 to 12.7V .Alow at least 1/2 hr after charging to check this voltage. A more through battery test would be to check the voltage under load . Most battery dealers ( incl. Halfords) would do this load test for free.
Assuming the battery is fine an alternator check should be carried out . With engine running at about 2,000 revs check voltage at battery terminals with all headlamps , fog lamps , fans,,air-con , heated rear window etc switched on . This voltage should be at least 14V . A good output would be 14.5 - 14.7V . If this check shows a much lower voltage then either the alternator or its regulator is faulty. The regulator can be fairly easily changed . A new regulator will be about £25 - £30 for a quality part .
When the old regulator is removed check that the carbon brushes are greater than the recommended minm. brush length . The brush length should compress its spring by at least about 5mm. If the brush length has worn below the recommended minm then the regulator should be changed.
Most Haynes manuals will have the minm brush length specified in the alternator section.

[deaconj999]

My battery Voltage cold is 12.44V. When I start the engine with the multimeter attached it drops to 11. whatever and goes back to 12.24 ish.

If I increase the revs and turn the lights and everything else on it kind of stays at 12.22 for a while. I then turn it off so that it doesn't kill the battery completely.

I did a check from the alternator ace to the battery and got a reading, can;t remember what the figure was.
I did a check from the plug on the alternator cable to the battery and go t another reading again can't remember the reading.

It has now made me think the alternator is U/S but before I changed to the new battery it must have charged the old one that kept going flat on me, because for a laugh, whilst I have the borrowed multimeter I thought I would check the old battery and it read 11.45V sat on the garage floor.

I hadn't thought about the regulator as I am no expert and I do not have a manual. I've go the plastic engine cover off and can see the alt is Bosch. Where and how do I get to the regulator ?

[vwcabriolet1971]

You really need a manual to remove an alternator or its' regulator.
What mileage has the car done and does it have a mechanically driven power steering pump or and electric motor driven pump ?
The electric power steering pump models are much easier to remove the alternator.

[deaconj999]

It's done 199k and i can't identify the water pump. It looks as though there is a pump that will have to be removed before i can get lower down to the alternator. This pump looks like a power steering pump as the hoses from it look like High pressure and not standard water hoses.

Any further advice would be welcomed as I am trying to avoid using a garage.

My local AUDI dealer thought he was a comedian when he quoted
£ 105 + vat for labour
£ 255.15 + vat for Bosch alternator
£ 235 + Vat for a Valeo
£ 323 + Vat for a Hitachi

But I suppose somebody has to fund the cost of their new showroom

[vwcabriolet1971]

With that kind of mileage its more than likely the alternator voltage regulator brushes are worn so much that there is little contact pressure to the carbon brushes. This would give rise to the syptoms you describe. It would be well worth checking the regulator brushes before comitting to buy a new alternator.

The pump I was referring to was the power steering pump not the water pump.
It would appear you have a hydraulic power steering pump driven from the alternator/air-con compressor ribbed belt.

To remove the alternator the following parts need to be removed in the listed sequence ( car on ramps) :-

Engine undertray and RHS wheel arch liner
Engine top acoustic cover
power steering pump
ribbed belt tensioner and ribbed belt
air-con compressor needs to be de-mounted but hoses left attached , this is heavy and needs to be tied out of the way
Then Alternator can be demounted & "juggled" out from the bottom.

This is not an easy job due to space restrictions and also the alternator has alignment bushes in the mounting holes that clamp the sides of the alternator frame to the mounting bracket . These bushes need to pulled back into the alternator frame before remounting. This can be done easily with a longish screw , nut and selection of washers.

The £ 105 + VAT for the labour charge sounds quite reasonable to me.

Best of luck if you intend to DIY.

[deaconj999]

Thanks very much for the info, but I am unable to perform this on my own. I broke my hip at xmas and therefore can;t see me crawling under the car.

Never Rains when it pours.

[Anubis8]

i had my mechanic have a look at it and he at first thought th alternator but then he took the battry off and it was placedon charge overnight. the next morning there wasstill no chargein the battery and so he tested it and it was faulty. so i got a new one for free as it was only a 3 month old battery. cheers anyway.

[deaconj999]

New alternator fitted - 120 Amp local garage recommended £ 259 all in. Always expesnive but the cheapest I could find.