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Alternator Fired

Gray79

Well-known member
Joined
28 Apr 2019
Messages
167
Went into the garage this morning to pull out the car, ready for the TIPEC Whitby meet, to be greeted by a funny burning smell. I didn't think too much of it, I just thought one of the neighbours must be having a garden fire. Started up the car, then alternator failure warning came up on the dash, on a quick inspection I could see where white smoke had come out of the back of the alternator :sad:
Out to my workshop with my car lift and tools, quick strip down to find that it had actually been on fire 🔥. Scary considering our bedroom is above my garage, and we have two young children in the house. Anyone know of any faults that could cause this, or will it just be the alternator that has failed? I don't want to fit a new one to find it might happen again.
 
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Hi, I recently purchased a late 2005 997 C2S and when trawling through the old invoices, I noticed that it had a new alternator fitted a few years back, and at the same time, the power cable from the front/battery area of the car to the rear of the car was replaced due to showing a very high resistance. I think that the failure of the cable can lead to damage to the alternator and starter motor ?? probably worth getting the cable checked, don't know if this might have led to the alternator fire though.

I'm certainly no expert, but thought my observations might be relevant.
Good luck.
 
Gray79 said:

DO NOT GO WITH THIS OUTFIT. they do not refurb the parts properly and seem to put a lick of paint over them!!

sent me the wrong item first and then the item that did turn up was 5hit and had to go back.

I ended up getting the item from CarParts4less and the bosch item.

at least you know its right and will last. you get a warranty too.

if you are handy with spanners then go for the Bosch item.

not worth doing any other route. trust me I tried it.

that is defo fubarred. sometimes Euro car parts will do an exchange on the item. happened to me on my 997s. put the ignition on and smoke came out the bag and the alternator just fried itself. perfect!!
 
*****, just ordered one from them, if it's no good I'll send it back.
 
Gray79, you have raised an issue that is of concern indeed, not only relative to the possibility of loosing a Porsche to fire damage but for much worse.

First off, I have been messing with vehicles for over 50 years and to date have not had one of my own suffer an alternator sourced fire. Secondly I kinda hope that building regs require integral garages to have a degree of fire retardation measures built into them during construction such as fire "resistant" doors and perhaps similar ceiling and wall materials utilised to slow down the progress of any fire.... though in a certain high rise tower.... modification to ORIGINAL.... construction seems to have lacked a degree of monitoring to determine materials suitability..?

Filling integral garages with all sorts of flammable items has it`s risks too, and to offset those to some degree it seems best to fit a smoke detector or a heat detector or both...today it is possible to have relative cheaply available interconnected detectors, that all sound together if any one unit detects an issue, thus if for any reason it may be possible that the detector in the garage might be inaudible due to it`s location, then the kitchen and/or stairway/hallway detector will also sound. These days interconnected detectors can be BOTH mains electricity and internal battery supplied to minimise voltage loss during power outages..

Of course having a smoke detector in a garage where exhaust fumes are expected has potential to create false alarms, however perhaps less so if the car is parked face in and avoiding ANY start up`s with the garage door closed.

A heat detector as might be used in a kitchen seems a better option though perhaps the slower response time is a consideration, but then location choices can make a difference...i.e. in a Porsche garage, mounted directly above the engine bay vents..?

As for the vehicle in question I have no idea as to whether the alternator is fused, well worth checking..? If fused my hope would be that the fuse is rated/ sized in amps relative to the maximum expected loading which can work both ways... relative to the internals of the alternator shorting out causing it to burn internally, in which case the battery would be adding fuel to the potential fire until the fuse blows protecting the wiring causing the fire to spread to other areas within the vehicle.... AND to protect the alternator it`s self from overloading relative to the battery and electrical system should a short circuit develop within un-fused circuitry in the wiring system other than within the alternator ...?

Just thinking in type.. Happy to be corrected.. :?:
 
When I had the house built (barn conversion) if I remember correctly, the garage ceiling was made up of a double layer of fire retardant plaster board that is supposed to be 14 minute protection, and also it has a fire door leading into the house. Still it is worrying that I could have lost my car, house and potentially much worse due to an alternator failure.
 
I'll just point out .. this is very rare indeed ... potentially into lottery winning numbers here ..

The problem is it's a huge cable direct from the battery .. there is no fuse ..

water , and i mean rather a lot on the alternator could .. just about i guess cause this .. i've not seen it though .

I have once in 15 years seen this .. erm .. the lead on the alternator had been fitted in the wrong slot .. there are two but use the wrong one and it just about shorts out ... so this was mechanical error and all it did was smoke a bit .

This seems to be some sort of regulator fault .

It is somewhat surprising what damage a 12 volt battery can actually do .. but it's not the voltage .. it's the amps stored within so to speak .
 
deMort said:
I'll just point out .. this is very rare indeed ... potentially into lottery winning numbers here ..

The problem is it's a huge cable direct from the battery .. there is no fuse ..

water , and i mean rather a lot on the alternator could .. just about i guess cause this .. i've not seen it though .

I have once in 15 years seen this .. erm .. the lead on the alternator had been fitted in the wrong slot .. there are two but use the wrong one and it just about shorts out ... so this was mechanical error and all it did was smoke a bit .

This seems to be some sort of regulator fault .

It is somewhat surprising what damage a 12 volt battery can actually do .. but it's not the voltage .. it's the amps stored within so to speak .

That's just my kind of luck, I'm not likely to win the lottery :nooo:

I didn't have any water on it, I never wash engine bays on cars, as I know the problems it can cause.

I don't expect any car of this age to be 100% reliable, but this Porsche is trying my patience, my old TVR was more reliable :frustrated:
 
I'm afraid i can only say this is a very rare fault .. 15 years in so far and i've not seen nor heard of a spontaneous combust like this .

Does Not help you i realise and will knock your confidence in the car which i fully understand .. luck .. sometimes it sucks i guess .

Sorry .
 
OP: are you sure it was actually on fire?. Mine let go in a similar fashion as I was pulling off the drive. No symptoms or anything before the warning light appeared flowedby a horrid stench. Mine was the original fitted unit and the diode pack let go and melted the commutator and shaft. Did not find any cable issues and all seems well🤞
 
brownspeed said:
OP: are you sure it was actually on fire?. Mine let go in a similar fashion as I was pulling off the drive. No symptoms or anything before the warning light appeared flowedby a horrid stench. Mine was the original fitted unit and the diode pack let go and melted the commutator and shaft. Did not find any cable issues and all seems well🤞

Yes definitely on fire, happened overnight whilst the car was switched off, there was burn marks on the alloy casting above the alternator, smoke stains all over the rear window and the plastic cover on the rear of the alternator was completely burnt off, I had to scrape the melted plastic off the engine under the alternator.
Haven't found any cable issues either.
 
NLW73 said:
Gray79 said:

DO NOT GO WITH THIS OUTFIT. they do not refurb the parts properly and seem to put a lick of paint over them!!

sent me the wrong item first and then the item that did turn up was 5hit and had to go back.

I ended up getting the item from CarParts4less and the bosch item.

at least you know its right and will last. you get a warranty too.

if you are handy with spanners then go for the Bosch item.

not worth doing any other route. trust me I tried it.

that is defo fubarred. sometimes Euro car parts will do an exchange on the item. happened to me on my 997s. put the ignition on and smoke came out the bag and the alternator just fried itself. perfect!!

Well it arrived today, so far so good. Looked identical, and brand new as advertised. Bolted in place and it worked straight away. Only time will tell, but £138.95 is better than £380 I got quoted for a new Bosch unit.
Fingers crossed it lasts.
 

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