Alternator failing ???

[Alan]

I went to jump start my nephews car today ( Vauxhall but with same 1.9 engine as mine ) and wonder if anyone has any ideas on what could be wrong with it.

This is the tale.

It had not been started for 48hrs and the battery read 6V nothing had been left on and previous to that it had been run every day with no starting problems.

The battery was new 6 months ago.

Put jump leads on and left it with my engine running for 4 or 5 minutes.

Started it, removed leads, voltage 13.4, raised rpm to 2000 voltage went up to 13.7 and stayed at that when back to tickover.

Left it running on tickover for 15 minutes and switched it off, voltage slowly dropped to 12.4.

Restarted it with meter connected, voltage dropped to 11.8 while cranking and stayed at that for a couple of seconds after the engine started and then slowly went up to 13.7 over the next 8 to 10 seconds. ( engine not taken above tickover )

I have the battery on charge and it's going to be checked tomorrow but I'm a bit worried about alternator with the time it took for the voltage to rise after the engine had started and wondering if it could be the cause of the flat battery.

Thanks for reading all comments welcome.  Alan

[sgould]

Sounds like a constant drain.  You need a ammeter that can read fairly high current.  Put that in the line from the battery when everything is "off".

Then pull each fuse in turn from all the fuseboxes until you find the circuit that is carrying current.

Then investigate that circuit.  You may find a broken wire or a stuck relay, or a hidden lamp that is stuck on.

[Petemate]

Spot-on diagnosis and advised course of action I reckon Will. Done that on many an older car years ago. As you said, essential to use an ammeter with high read capability. Works well.

[Alan]

I think the battery is ok because my charger has shut off saying it's fully charged and I don't think it would do that if the battery had a duff cell.

He was having a similar problem before he changed the battery. Sometimes it would start sometimes the battery would be flat after standing overnight, the garage did a drop test on it and said it was u/s so he bought a new one. It was the original 8 yrs old battery and replacing it did cure the problem but it looks like it could have been something like a sticking relay then too.

I'll have to hope having the battery off and charging it fixes it for a while to give me chance to find a cheap ammeter and so that it's warmer when I have to spend time finding the circuit with the high drain lol.

[Alan]

Well that was easy. Connected the battery and the cooling fan started running.

With the fuse labeled "cooling fan 2 " removed the fan stops and google shows it is a common Zafira fault to have the cooling fan running all the time.

What I couldn't find on google was what cooling fan 2 relates to, is it for cooling the engine or is it for the air con ?

I've looked through the handbook for my 93 and can't find any mention of fuses or relays for the cooling fans to compare them.

Do Saabs have the same " cooling fan 1 / 2 " if so what is cooling fan 2 for.

[sgould]

Saab show a pair of fans.  Power to the relay box on top of the radiator.  Relays switched by the engine management control unit.

The fuses shown in the diagram are said to be on the side of the battery box.

[aerojon]

it's a Vauxhall wiring will be different..

[Alan]

it's a Vauxhall wiring will be different..

They are wired different but I'm hoping they work the same way so we can be sure he will not have cooling problems with one of the fuses removed.
We can't find anything about how the twin fan system works so all we can do is compare it with mine. ie. does one fan come on initially then the second if the first doesn't provide enough cooling or do both come on together at all times.
It doesn't help that his air con needs a regas and he only has a high temp warning light not a gauge.

[nine-fiver]

Change the relay? Cheap and cheerful solution. If the fan is stuck on full time the relay is the prime cause?

[Alan]

It seems to be an intermittent fault, the fan did not run when we jump started it but did when we put the fully charged battery back on. we could hear the relay clicking as it turned the fan on and off so I think it's more to do with the engine management unit ( or it's Zafira equivalent ).

[nine-fiver]

Could be a broken wire too. It happens more often than you might think. Disconnect the plug to the fan and run a temporary line direct from the battery, or another one off the car, to see if it is behaving. Try a multimeter in the circuit too.
Alsomto consider, I had an Astra a while back of the same vintage and parts of the loom in the engine bay had to be replaced, just so the battery would hold charge and it would start with full amps.

[Alan]

They are all on the "to do" list lol. At the moment with there being two fans we are still not sure if we should be looking at the engine temperature side, the air con side or the control unit for the fault.
It's been too cold here to get anything up to the temperature needed to get the cooling fans to cut in on my car to give us an idea how they work but it means there is not much chance if his overheating if it's the engine cooling fan we've removed the fuse for.