Alternator Compatibility

Morning folks

Well, I got into the S1 this morning to drive to work, and about 20 meters up the road I looked down to see the battery light on. Stopped and restarted, still on.

Checked the belt etc and its fine, and turning the alternator pulley Ok. It did squeal briefly on a very wet day earlier in the week, so it probably could do with tightening, but on this occasion it appeared to be working normally.

As I was late, I didn't have time to get the multimeter out, but drove back home and took the S2 (much to SWMBO's delight, she had planned on going shopping ).

My question is, if it comes to the worst, which other PSA cars have a compatible alternator for the 2.0i? I guess I could take one from the other Xantia, but am unsure of any differences. I may have to resort to raiding a Peugeot, as the chances of seeing a petrol XM in a scrapyard here are virtually nil.

If anyone knows what will do it, I'd appreciate hearing your thoughts.

Cheers

Ciarán

Hi Ciaran

I think electrically they are all very similar, apart from the output, but then again I would think any one would be high enough unless your car is fitted with a public address system or searchlights It's only the mountings that vary, I'm sure you should be able to find one to fit without to much trouble.

Peter.N.

Hi Ciaran,

Although a failed alternator is the worst possible scenario lets take a step back before condemning it to the scrap heap. There are lots of tests do to first with your multimeter. Of the two main electrical components in an alternator ie the voltage regulator/brush pack and the rotor/stator windings then the brush pack is far more likely to go. The brush pack can be replaced as a unit sometimes even with the alternator left in place.

Lets hear about the usual test results before throwing the baby out with the bathwater. Do you have a wiring diagram for your model? Do you need a hand to locate the measuring points? The first and foremost test is the presence of 12v at the terminal of the small wire connected to the alternator. If absent, then that circuit needs to be traced back to the ignition switch and fuse box.

Cheers

noz

Hi Peter, Noz, thanks for the replies.

I will attempt to do some of the usual tests when I get home from work. Having to work this weekend has really put a spanner in the works, because I need the car for during the week, and probably won't have much time to go anywhere then either.

If it is the brush pack, I wonder how readily obtainable they are. My main problem is time, if its something I'm going to have to order and wait a few days on, I can't afford to hang around with the car off the road unfortunately, so could be forced into just getting a new unit.
If on the other hand, they're easily extracted from another alternator, this may well be a viable option.

As you say though, no point condemning the lot until I know more, it may even be something simple, (hopefully!).
As soon as I can get out of here I'll go home and get the meter out, see if I can find out more.

Has it ever been known for a dodgy / failing battery to put the light on, or is it always a charging issue? The reason I ask is its been a bit weak to start a few times lately, now that I think of it...

Cheers for the help so far

Ciarán

Hi Ciaran

The light is connected between the battery + and the alternator field/rotor, so as soon as the alternator voltage rises to 12v + there is no voltage across the lamp, so it goes out. The fact that yours is on would indicate that there is in fact no output from the alternator. The only other cause would be if its not going round.

Peter.N.

i just sent a 2.0i turbo to the scappies? (vandals) but you could try giving it a clout with a blunt instrument where the brushes/sliprings are and see if it responds , chances are that it just wants brushes, (about £3/6) a set or £10/20 if a diode pack is built in?, the only time ive had to buy an alternator is when a mounting bracket broke? you can rebuild one in about 4 hours , and im a joiner? i always replace the bearings as well as the brushes, the hardest part is either getting the thing off or getting the pully off to do the front bearing????

Hi Peter, Terry.

Well, I've had the meter on the battery, 12v without the engine running, 12v with it running
The voltage at the alternator output terminal is 12v (though not sure if thats just measuring just the battery voltage), and the thinner wire is putting out 2.8v, not sure if that's normal, I'm presuming not after reading your last comment, Peter.

So I guess its obvious theres no alternator output. I guess the next question is which particular component has failed, and indeed how would you go about telling the difference between diode or brush failure?

I'm wondering if the Xantia unit has any interchangable parts. Even if the entire unit was transferable, it would get by in the meantime until I could obtain parts for this one...

Ciarán

Hi Ciaran

You should have about 14v across the battery if the alternator is charging and maybe a little more on the large alternator terminal.

Peter.N.

Seems I now have a different problem, not sure if its related.

I went out there to check what type of alternator it is, and it now won't start. Battery voltage is still good, and the green 'Ok' indicator is showing on the battery itself.
Now when I crank it, it turns over very slowly, and eventually just grinds to a halt, and then does the clicking solenoid thing when you retry it. Despite turning slowly, the starter sounds quite high pitched and wheezy, and gets very hot to the touch, as if its jamming or struggling to turn.
I could understand that if the battery was low, but it seems fine (despite the alternator).
This is quite strange, as it was starting fine half an hour ago. I'm unsure if it could be tied in with this charging problem, I would suspect not, as the alternator doesn't have any direct connection to the starter, or does it?

Ciarán

...and now, when I attempt to start it, it just clicks the solenoid... then when the key is released, the rev counter shoots halfway up, and the blower motor comes on full blast, despite the switch being at 0....

Sorry, what?!!

This post has been edited by Ciaran on March 01, 2008 10:42 pm

Ciaran,

I think theres a wire from the alternator to the the starter motor, which can come loose and is quite difficult to check/tighten at the starter motor end? Something to check anyway.

Bashing the starter motor with a heavy pipe apparently can help with the "won't start even though turning over" issue. I ended up having a new starter motor when I had this (always wouldn't start in bad places like Heathrow short term car park, weekend away in the Black Mountains etc).

Battery light on does indicate alternator failure, I tried to kid myself it was bad connections for a while during my last (and longest) alternator saga. Indie does want to swap them out rather than refurb then though, wish I'd kept the original one for refurbing now, but been OK since Nov 05 (fingers crossed).

Do you have a jump start pack or a battery charger? I found I could run the car for a short period with the jump start pack plugged into the lighter socket during last alternator saga (better in the day when you don't have to run the lights, though).

Hope this helps, I am a dabbler not an expert when it comes to cars.

This post has been edited by DrTim on March 01, 2008 10:51 pm

low voltage causing electrix to misbehave mate!

Do you have air-con? If so, check that the compressor is not seized.
(Just slacken off the auxiliary belt enogh to let the pulley run free).
Two possibles then: 1. Single wire to top a/c compressor is not connected , but most likely 2. the compressor is seized. That will stop *any* chance of turning the engine over.
Two solutions 1. change the compressor (I have a spare) or 2. get (cut?) the belt off and fit a non-a/c belt so as to drive the alternator and LHM pump until you get time to sort out the compressor.
Don't ask !

Hi Tim & techman

Thanks for your replies, they've given me a few things to consider.
Tim, I did suspect some sort of connection between the alternator and starter, though can see no evidence of this at the alternator end. In fact, there are only two connections to it, the thin wire which disappears into the main loom, and I presume feeds the dash light etc, and the main 'B+' feed cable which goes to the battery, and thats it. Does that sound normal? I could have sworn there should be more than two connections, but I can't see any evidence of disconnected cables at all.

Techman, yes, it does indeed have AC (wasn't used during the summer due to blower being dead), and the seized compressor theory is an interesting one. It would certainly explain why it was starting fine one minute (despite the alternator issue, the battery seems good), and struggling the next. I also thought I smelt like a motor burning smell for a brief few seconds after it started for the last time, could explain why its been sounding a bit odd when cranking....
The wire on top of the compressor is still present, I know that much, but will check it properly tomorrow. Where does the other end of it run to, just out of interest, the famed 'compressor cutoff relay' by any chance?

Cheers

Ciarán

Are you sure the cable from alternator to battery doens't "stop off" at the starter motor on the way?

I remember not having much fun trying to diagnose what eventually turned out to be a failing (but less than one year old) alternator in the dark and wet November evenings of 2005, not much else, sorry.