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Overheating/ burning alternator

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4 replies to this topic

#1 lucasdemoley


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Posted 05 December 2009 - 11:23 AM


I had a quick search and couldnt find anything similar, so I was wondering if anyone might have any idea what might be at fault so I can give the garage a point in the right direction.

Car is a 2.0 td 2001, Its the 115ps version I think.

Basicly sitting outside waiting for my gf I had a few electrics on and was reving at about 2k for 5mins. There was a burning smell but though it was neighbours burning something (having work done to their house). Anyway, drive into town (5mins drive) pull up and spot loads of smoke comming from under the bonnet. I took a look and it was comming from around the alternator. RAC confirmed that the alternator was burning out, however there were no battery lights on my dash or any running issues. Got taken to a garage (the one I normaly go to is a 1hr drive away so settled on this garage) where they had a look with the RAC guy and the charge/ voltage was ok (14.7v, a little on high side but no serious).

Anyway, £200 later and I had a new alternator. I tried to pick the car up on Wednesday however the garage (who had litteraly just managed to fit it before my arrival) thought it may be doing something similar again, so I left it with them. Went to pick it up today, they had taken it for a test drive and said it was ok now. Anyway I drive it back to my gfs place (5min drive) and its kinda smelly again. I turned all my electrics on and rev'd it at approx 2k and after a min or two it started to smoke again.

Its now back in the garage (its an odd fault so dont blaim them) but I feel that they are not sure where to start looking! My initial thought was a damaged earth, but the RAC and Garage dissmissed that idea (I have/had a fiesta project car so know my way around cars and simple car electrics), so not sure if that is a possible cause or if its going to be something more obscure?

So any ideas? There was no battery light on my dash showing any issues and it was running fine.

Help appriciated as I am now left running around in my gf's crap clio without an exhaust, not great when I do alot of traveling to meetings for work!

#2 motorman116


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Posted 05 December 2009 - 06:47 PM

I would of said that the live wire from the alternator is earthing out somewhere, thus causing the problem with the alternator
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#3 lucasdemoley


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Posted 06 December 2009 - 10:58 AM

I thought the alternator was connected directly to the battery + (thats how it was on my fiesta) and as such would this not just burn out the + cable even with the engine off? I'm not clued up on the mondeo wiring though.

Any other ideas?

#4 huw1000


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Posted 06 December 2009 - 04:02 PM

The 14.7volt reading is completely normal for modern Fords smart charging system so you can ignore that.

I'd suspect a short somewhere too.

According the my Haynes manual the alternator is wired to the starter motor and then connected to the battery on one wire, engine fusebox on another and 'engine management' which I guess is the ECU on two wires.
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#5 lucasdemoley


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Posted 16 January 2010 - 10:28 AM


For others with this issue, it turns out the battery was at fault, causing overcharging of the alternator. All the test done to the battery it still showed up ok, so must have been some randome fault.

The replacment battery also sorted a starting issue I was having, where if I didnt turn the key then wait for the lights to go out before starting, and just turn the car on the car would idle at like 500rpm, very lump, wouldnt rev and would often cut out.