alternator on 20 a day

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Vanny
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alternator on 20 a day

Post by Vanny » Sun Oct 23, 2005 6:47 pm

a week on from the start of battle with the stupid car and the new engine is in and running (kinda) with but one problem! After two hours wrestling with the various alternator belts, pulleys, idlers etc i finally managed to get a belt to fit and the small problem is;

The alternator has now taken up smoking, approximately 20 to 25 a day! Now heres the thing, it was running just fine on the old engine, and there is no light on the dash warning me of impeding danger, but after running for more than 30 ish seconds i get a lovely acrid white smoke!

I was careful to cover up the alternator when dismantling the old alternator (which has less than 500miles on it after a kind donation following the previous one filling its self with LHM), so to be honest i have no idea whats going on. Wires are all correctly hooked up as best i can tell (havent had a meter on it yet), and once the car is started (with the aid of the AX) it seems to run happily enough and doesnt suddely plunge into an abys of darkness!

Im a bit screwed without it as the car has a Xantia pump (also giving me problems) at the cambelt end of the car, so i cant just ignore it! GOnna get a meter out (if ican find one) then try unhooking it and see what happens!


Any suggestions?? I certainly cant afford ANOTHER alternator, though i have a few to swap. Anyone with a spare locally??

jeremy
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Post by jeremy » Sun Oct 23, 2005 8:29 pm

Its always difficult to diagnose problems when there are a number of temporary arrangements. If everything was working properly (ie starting on its own battery, permanent connections everywhere) I'd say that the voltage regulation stage of the regulator had failed (zenner diode) and the thing was running away and trying to charge at a high voltage. This would mean that the thing was able to push a very high current through the battery and was overheating the windings.

However a defective battery may not offer the correct resistance especially if one cell has shorted. I imagine it would work something like this:

A lead acid cell has a remarkably stable output and stays at about 2 volts until almost fully discharged. If it really is discharged instead of presenting about 11 volts to the alternator it could be presenting 9 and I'm sure you will appreciate that a higher than normal current will be produced.

Get busy with a meter (digitals can be had for £3 or so). A fully charged battery that has been standing overnight should give 12.6 volts or so, and while on charge it should rise to 13.6 to 14.4 volts. If its going over that you've got problems but the circuit is actually very simple - and should be direct from the output terminal of the alternator to the positive battery terminal, the other side being earth. Remember you can measure the resistance in a lead under charge by connecting a voltmeter in parallel. the reading should be minimal (1/4 volt is max and really too much with the thing charging. The same appplies to the earth.

Jeremy

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Vanny
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Post by Vanny » Mon Oct 24, 2005 10:39 am

Hmmm, what a drag! Hadnt thought about the battery as a cause of the problem, it certainly doesnt seem to hold its charge when charged from the mains! I can general squeeze some juice into it, but it takes about 5/6 starting attempts (no more than 5 seconds on the key) before it dies, and thats after an hour on fast charge, sees a bit fast to give up really.

Thing is the battery is only a couple of months old (think the reciept is still in the car!), and its a Bosch silverline one as well. Off the top of my head i think its an over rated battery for the engine but the AX has the same battery (meant to be for fords) and has never had a problem!


Think the alternator is gonna be US now though which means i cant do anything more with the car on cash grounds! So close yet so damn far, gonna get a volvo 240 when this heapo chit finnaly gives up!


I tried disconnecting the main feed wire and this stemmed the smoke a lot, but after a short while it smoked a little! GRRRRR think the crank pulley is goosed as well as it doesnt seem to be sat on the crank properly and spins off balance, just another thing to have to resolve!

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cavmad
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Post by cavmad » Mon Oct 24, 2005 11:22 am

Vanny, I have a battery you can have for nothing. Not had any problems with it so far, it`s the one that was (still is :? ) on the estate I bought, as I`ve yet to put the one on from my old BX.
Away all week now but back at weekend if you want it.
Vauxhall apologist.

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Kitch
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Post by Kitch » Mon Oct 24, 2005 6:33 pm

I wish I still smoked. Its great.