Any advice appreciated regarding engine fire.

[Alondonboy]

Had an engine fire on my Bayliner Sunday. Luckily it wasn't too bad and was near marina so got a tow home.

After inspection I found that the alternator has completely melted and 2 of the 4 wires from it have been melted bare. All 12v power was, and still is, lost so am a bit concerned as no bilge pumps etc. Have been reading up about it and have seen there is a cut off breaker mounted on the engine so am going to try and find this to reinstate basic power (I have isolated the alternator and will cover the bare wires and ends before doing this). I'm also keen just to crank the engine as someone has said it may have seized, can't move it by hand (not sure if you can anyway) but would put my mind at rest if it just moved.

If anyone has had this happen to them or has any information/advice or warnings, even perhaps knows any good boat mechanics with good electrical knowledge, all feedback would be much appreciated

 

[david_bagshaw]

You were very lucky it wasnt worse !

Cant tell if the alternator it self is the cause or wires nearby rubbing through and shorting out. Not totally unusual in the truck world,

very unlikely to have damaged the engine.
Dont want to tell you how to suck eggs etc, my plan would be;-

disconnect batts, if not already done.



All the wires to the alternator need checking for heat damage along with whatever they are connected to.

At the moment you dont know if the alt is the cause of the fire or a by product of a short else where , or a poor battery overloading the charge system. determine if there is another short else where that caused the alt to fry. Probably not likely, but you dont want another fry up. Check the battery for dead cells, and overheating, and loss of electrolyte.

 

[Alondonboy]

I've cut the wires to the alternator so it's isolated now, just need to screen them over where they're burnt through. Don't really want to disconnect batteries as I would like to get power back on for bilge pumps, especially in this weather.

Been told some 'horror stories' about debris blocking the prop, the engine overheating instantly and burning out the alternator then seizing up etc, but I tend to take some of these 'nautical nightmares' lightly as a lot of people like to scaremonger.

I'm pretty savvy on electrics just not so much on the mechanical side plus boats are a whole new ball game. Really would just like to know the engine's not wrecked.

 

[Actionmat]

Mine stopped charging and on inspection I found the wires going from the alternator to the control box were melted together and the regulator had blown. I'm sure the wires rubbing in a metal sleeve had caused it. Burned wiring replaced, new regulator from eBay and all seems well.

Good luck with yours!

I'd take the Alternator off and take it somewhere to be tested for a start. Newport Auto Electrics, 55 Cambridge Road, Hounslow, tested mine and gave it the all clear for a fiver.

 

[Alondonboy]

Thats what's left of the alternator in the pictures. What wasn't metal was carbonised.

 

[Actionmat]

Sorry, I couldn't see the pics on my phone. The chap at Newport would rebuild a nuked one or may have a second hand or rebuilt replacement on the shelf. It's very old school with a tin shack out the back stacked to the rafters with second hand alternators and starters. It's a dying art.

 

[Alondonboy]

Was given an estimate of around £300 but then found a new or 'factory refurbed one online for £135 so not too fussed about that, more worried about the wiring and cause. Also Labour is going to up the price as well.

 

[david_bagshaw]

Have you checked the batteries for electrolyte level, along with looking for case buckling. How old?

Also check the rubber pipes on the engine that might have been damaged in the burn up.

Very unlikely to have engine damage. Alt couldnt cause a stall, or lock up as the drive belt would slip first. Not similar to cam belt failure.

Too put your mind at ease re engine main parts, turn with a spanner on the crankshaft nut, or turn alt pulley holding belts down to get sufficient grip. Even quite big engines can be turned, so long as very slowly to allow the compression to leak past the rings.

some engines have a plug near the flywheel ring gear, where a screw driver can move the engine tooth by tooth. If the gearbox is not hydraulic, put it in gear and turn prop shaft (might not be possible if you have out drives)

 

[prof pat pending]

You could run a temporary lead from a battery to the bilge pump switch to put your mind at ease over the weather.
This would make it possible to leave everything else disconnected while you sort it all out, which is probably safer in the long run.

As for turning the engine, you don't say if it's petrol or an oil burner, but taking the plugs out will make it easier to turn the engine by hand...no compression

 

[Alondonboy]

OK

Been on boat all afternoon. Found reset breaker on engine, doesn't appear to be doing anything. Can see now that the fire has burnt through the top of the black plastic container under the alternator. Can't see what it is at the moment as cannot for the life of me physically get the alternator out.

The can't get the belt release undone and can't rotate the belt at all to run it off. Engine won't rotate an inch so still don't know if it's seized and no electrics.