Valeo Alternator Insides

addo · Post by **addo** » 22 Nov 2010, 06:42

I've got an odd condition with the car.

Sometimes upon startup, there appears to be a dead short. It drops sufficient current to reset the clock and radio, the interior lights barely glow and no way will the engine turn over. There is no smell of smoke.

What I'm wondering is (having just replaced the starter) - whether there is a buildup of oily carbon sludge in the alternator, that could be shorting out. Engine is on about 110K miles, original alternator; newish battery.

I don't have a heavy keyring so damage to the ignition switch seems less likely (plus I'd expect to smell something inside the cabin).

One fellow whose travails I followed, had massively worn slip rings in his Valeo alternator. Anyone else experienced this? Wary of dismantling something and then crippling it for a fortnight while parts are located. A brand new Valeo alternator is £408 from Woods.

Cheers, Adam.

Post by **xantia_v6** » 22 Nov 2010, 08:34

Can you clarify "on startup"?

My first guess is a battery with a faulty internal weld between the cells, which can cause problems like that. Can you borrow another battery to try?

addo · Post by **addo** » 22 Nov 2010, 08:52

Well, you turn the key and it immediately starts cranking - then basically dies in the proverbial.

I'd have thought a duff battery would give consistent results - this is highly intermittent.

HDI · Post by **HDI** » 22 Nov 2010, 09:18

Check earths and battery cables. Check battery terminal voltage and starter terminal voltage during starting.

Post by **xantia_v6** » 22 Nov 2010, 09:38

addo wrote:Well, you turn the key and it immediately starts cranking - then basically dies in the proverbial.

I'd have thought a duff battery would give consistent results - this is highly intermittent.

It is a specific manufacturing defect which tends to show up in near new batteries. The cells in the battery are manufactured individually and then welded together. If one of the welds is not done properly, the lead tails (can't remember the correct name for them in this context) are just touching to form an unreliable connection which conducts at low currents, but melts slightly at higher currents, giving a high resistance, recovering after cooling.

Measure the battery voltage right at the battery posts (preferably with an analogue meter) while cranking the engine, see if the battery voltage suddenly dies.

citroenxm · Post by **citroenxm** » 22 Nov 2010, 10:07

Ive seen MANY of a Comm on the altinatior, were the brush's run to make a charge, to wear out FASTER then brush's them selfs!!!

Its only a soft metal, copper or brass (goldish type colour anyway) and a recent one saw the lower part worn right down to the centre..

All revealed after removing the Diode and Brush Pack..

Paul

cachaciero · Post by **cachaciero** » 22 Nov 2010, 11:25

Hmmm.... Changed the starter motor you say? was this as part of trying to find this problem or prior to it? because this problem sounds like a classic shorted winding or two in the starter motor.

cachaciero

addo · Post by **addo** » 22 Nov 2010, 11:40

I actually overhauled the starter, not a true replacement. Did all porous bushes, solenoid, brushes and repacked the planetary gears.

Due to having the 'flu I plain forgot to check each set of windings. All looked perfect; no odd colouration.

Symptom 2 - which may be connected - a low throttle stumble at times. It had this well before the battery change (April-ish) and it has been more pronounced again in recent times. The HP pump is weeping some LHM onto the alternator, although I rather enthusiastically degrease the area often.

Also noted - I load the alternator more per mile than many people, using the aircon a lot and driving with low beams on, much of the time. For that reason, slip ring wear might be more of an issue?

Clogzz · Post by **Clogzz** » 22 Nov 2010, 11:42

Often had that with the Xantia.
Found it because the headlights were flickering when riding over bumps.
It’s something like glazing of the insides of the battery clamps.
Fixed it by cleaning with a metal wire brush.
The taper of the clamps doesn’t always match the taper of the posts.

cachaciero · Post by **cachaciero** » 23 Nov 2010, 16:44

I can't envisage any alternator defect that would give you the symptoms you have that does not involve either a blown rectifier stack or regulator, and of course with either of those problems you would get no charge apart from anything else.

My money is still on the starter motor or battery.

cachaciero

addo · Post by **addo** » 28 Nov 2010, 05:52

Car's done a splendid thing today. Died at the bottom of my (sloping) driveway when I went to start it, blocking in the other two "goers".

Being Sunday and local parts places being the zoo/crêche they are, no way had I any hope of getting a battery test done.

When the key is turned and the car is basically not turning the starter, the battery voltage remains around 12.7 between posts.

No smoking of any leads, not even discernable warming. I don't think the solenoid clicked, even.

In my efforts at troubleshooting, I dropped a deep well 13mm socket behind the alternator, requiring removal of the inlet fanimold.

Now it's raining cats and dogs, and I have a dismembered motor blocking the drive. Have got a couple of things to test now, but overall - what a frustrating episode!

***PART II***

Hooked the Alfa via its front tow eye, to the Xantia towbar and using reverse, dragged the mongrel uphill four-odd feet. Now I have the 405 able to "escape".

Connected the starter without alternator hooked in, and the car cranked just fine; plenty of vigour. Hooked up the alternator leads and it cranked fine again! Struth. There is some carbon dust visible at the alternator rear; knowing what lifespan city driven UK Xantias/XMs get on an alternator would be handy.

It's certainly suggesting a rubbish battery (Delco, BTW).

Post by **Peter.N.** » 28 Nov 2010, 10:14

If the battery voltage is remaining at 12.7v then clearly it is not connected to the starter so check all battery/earth/starter connections, if there was a load on the battery heavy enough to pull the voltage right down you would find that the leads and connectors would be getting warm/hot.

Peter

Post by **CitroJim** » 28 Nov 2010, 10:32

As Peter says Adam. I'm beginning to think the alternator is a bit of a red herring in all of this. next time it happens, try to measure the voltage on the large and small solenoid terminals. The large one is the battery direct and the small one will be the feed from the ignition switch.

I'm beginning to wonder if you're loosing the feed from the ignition switch. It's common on V6 Xantias that the switch develops a high resistance and the same (ish) symptoms apply. On an auto it's a showstopper of course.

V6 owners fit a helper relay in the starter solenoid circuit to overcome this issue; It might just work for you.

Also, on yours, is the starter inhibit relay OK? This one is the one that prevents starting in anything but P or N and has to carry the full starter solenoid current. It's operated from the gearbox multi-function switch. Even that could be a tad iffy...

addo · Post by **addo** » 28 Nov 2010, 11:14

I'd wondered about an inhibitor switch, but had been working off the 2.1TD start/charge schematic not your AL4 scan - doh!

Used to jump start an old Ford with a 20¢ coin or brass housekey all the time; just bridging the main positive to solenoid trigger. I'm more leery with the Xantia because if it jumps into life (and in gear) you can't get out of the way so fast!

Will have the battery tested thoroughly tomorrow, for sure.

addo · Post by **addo** » 29 Nov 2010, 08:45

Battery checked out as 100% good, which isn't in a way.

Recently I asked about Auxiliary belt life. This one has sustained over 80.000km in a harsh environment.