Fire in engine bay

**Dale** · 29-10-2008, 02:38 PM

The other day I returned to my car from a store to see a very small amount of smoke coming out from under the engine bay, smelt electrical to me. It was relatively minor and at the time I pinned it down to being the alternator power wire having shorted somewhere as that's around where the split loom etc had been burnt.

Looking at it today I've traced the loom back and found no damage to wires that would have caused them to short and no fuses blown. I would assume that since the engine was off the alternator power wire would be the only one in the vicinity to have power still running to it, and would have been the one to short.

Is it possible something else started the fire and just got the insulation on the wires burning? Alternator maybe?

It's puzzling me how it started and what I should replace to be on the safe side... obviously the damaged wiring needs to be replaced, but I'm thinking if it was a short that fuses should have blown. I'm thinking I'll replace the alternator too (the noise suppressor on it seemed to cop more damage than anything).

The car is an ST162 celica if that's of any relevance.

**oldcorollas** · 29-10-2008, 02:51 PM

is the alt near the exhaust?
the noise suppressor is an insulator between power and ground. if it's internal insulation broke down (say, with being exposed to heat), then it could short internally.

does the power wire from battery to alternator have a fuse on it, or fusible link?
might be good to put a circuit breaker on there, or an easily changable fuse.

if the alt is near the exhaust, a simple metal heat shield between them could help

**cambelt** · 29-10-2008, 03:11 PM

Lucky you caught it when you did or you may have lost yr car.
As a side note guys 12 Volt car wiring should allways be condidered as dangerous . Allways fuse things and check conections are not going to short.
On St 162,s the alt is close to the exhaust and the Main B+ wires insulation does crack over time , Double check it.
Dave

**Dale** · 29-10-2008, 03:13 PM

It's pretty close to the exhaust

The power wire from battery to alternator splits at two points in the loom, but ultimately goes back to a fusible link at the battery (40amp FL, seems a little low?)... the weird thing was that it wasn't blown

I just pulled the alternator off, it was very black inside and didn't spin anywhere near as freely as my spare. Makes me think the bearing in it might be gone, causing excessive heat, causing the noise suppressors internals to break down and short, causing the fire (combined with the hottest day we've had in a while here)

**oldcorollas** · 29-10-2008, 04:23 PM

thats quite possible.. can you take some pics of it? of the inside and stuff?
it could have also had diodes break down, or insualtion of the wires break down, or a foreign object get in there..
or carbon work from the brushes has been building in to form a conductive path...

but those are not so common...
of course it could just be fubared

**Jt_70R** · 29-10-2008, 08:50 PM

Dont know if this will help, but this happened to my old 162 a while ago. Rubbed through on the lifting lug.

Was wondering why it kept randomly blowing the charge fuse lol.

Im guessing since you havent blown any fuses it isnt actually a shorting issue.

**Dale** · 29-10-2008, 10:05 PM

I'm almost certain it was the alternator that started the fire now... even after the insulation on the wires burnt through in the small section there was no path to ground so no fuses blew.

I replaced the alternator and replaced the wires that were damaged and all seems well now, I'll keep an eye on it over the next few days.

OC - I'll try and pull it apart when I get a chance to see what happened, the noise suppressor looks quite molten inside now that I've seen it up close from a better angle

Jt - Looks familiar except mine is burnt through just forward of the exhaust cam cover, I checked all my wiring around the lifting lug and all seemed well, I think series 2 is slightly different around that lug as well

**Mos** · 30-10-2008, 04:25 AM

The alt fuse should be the 80A one on the ST162 - ie if the alternator was shorting, or had a low resistance, to ground, the current supplied by the battery will be running through the 80A fuse and not the 40A fuse...
Did you find any broken strands in the burnt section? they should still be identifiable.

**Dale** · 30-10-2008, 11:49 AM

Series 2 ST162 don't seem to have the 80A Alternator fuse from what I've seen.. by memory series 1 did, and I know ST165s had the 80A Alternator fuse.

Mine only has the 30A AM1 and a 40A AM2 fuse in the box that sits just off the battery

I looked at the burnt section closer yesterday and found that it hadn't actually burnt completely through on any of the wire, so I don't think any strands were broken, but I will have a closer look when I'm home

Would it be a good idea to short the alternator wire to ground momentarily to see if it blows the AM2 fuse? If it doesn't blow then I'll know there's a potential problem there?