31 replies to this topic

[maieth]

Hi folks.

My wife's attention seeking mini decided to s**t itself again yesterday, choosing, for the second time, the undeniably attention grabbing approach of an electrical fire.

I'm after any initial thoughts on diagnosis or best/worst case scenarios.  I've not undertaken a proper inspection yet and will update with more details when possible.

 

Basic info:

• Wife started the car fine after I left for work, drove less than 100 yards to the end of our road before hearing a "weird" noise and seeing what she believed to be steam coming from bonnet.  Best description I can get of the sound is 'grinding' - nice.
• She cut the ignition and got out to check under bonnet, at which point the car began trying to start again.  She removed the keys, but this made no difference, and the car did indeed manage to get itself running. She tried switching ignition on and off and stalling the engine, but there was clearly a dead short at this point and the car just kept firing the ignition until the battery drained.
• At the same time, she spotted small, localised flames behind the grill and called fire brigade.  Successful attempts were made to stop the flames getting worse.
• Fire brigade disconnected the battery and fire stopped.
• IN the small amount of time I've had to check it this morning, there's extensive damage to the connections to the starter solenoid. These are little more than ash and melted rubber now, but no further damage that I can see yet.

Background:

• We've had recent problems with head gasket with the car losing oil into water and vise versa. We've changed the head gasket twice. On the most recent change we had the cylinder head fully refurbed - cleaned, pressure tested, skimmed, valves re-seated and new stem seals.
• Had previous electrical problems with the lighting loom.  A cable badly routed through the engine by previous owner created a short on that occasion and burned out half the lighting wiring.  Seems totally unconnected to current issue as far as I can see.

 

 

At the moment I'm most concerned by the 'grinding' noise, and guessing that the stater motor could have seized, but any other ideas would be welcome.

 

Thanks

 

Rich.

(ask if you need more info)

 

[lrostoke]

The grinding could have been the starter sticking on.

 

I'm thinking solenoid seized up, If a ballast system this would allow the coil to get power via the white/yellow wire so would start with ignition off.

 

Solenoid seized and starter stuck I guess could create enough heat and power draw to melt cables

Edited by lrostoke, 14 May 2013 - 09:28 AM.

[mini maniac]

 

 

• We've had recent problems with head gasket with the car losing oil into water and vise versa. We've changed the head gasket twice. On the most recent change we had the cylinder head fully refurbed - cleaned, pressure tested, skimmed, valves re-seated and new stem seals.

 

Hi maieth,

The issue with your oil/water could be the result of a water pump fault.

 

Your electrical fire on the other hand will not be connected unless you literally have water spurting out of the block or a pipe onto some wiring.

 

If the fire was pin pointed to the starter motor, was it a damp day or are you aware of the age and state of the connections on the starter motor at all before the fire?

 

I ask this because if there was corrosion or damp across connections this would lead to the car trying to turn itself over (I guess that's what you meant by 'tried to start itself') as there is a permanent live straight from the battery which is then switched live by the ignition, if there was a chance of a short the permanent live could easily of shorted to the switch live leading to the car turning itself over and then overheating the switch live wiring which then could cause a fire.

 

Sorry to go drag on but seems to be a domino affect if you catch my drift.

 

To rectify this problem you will just need to rewire the connections be cutting off the burnt pieces and soldering on new ones with properly insulated connectors to avoid damp. Alternatively you may find the other ends of these wires and replace them entirely if your electrical expertise  concerns you.

 

Hope this helps.

 

Switz

[mini maniac]

Secondly, the 'grinding noise' could be the result of the starter motor seizing as Irostoke said, or another short across connections and the solenoid remained live holding the engaged gear against the flywheel which would result in a wurring/whiny sound as the starter would be being over rotated by the engine once it had started.

 

Switz

[maieth]

 

Hi maieth,

The issue with your oil/water could be the result of a water pump fault.

 

 

 Heh, ironically, it was replacing the water pump that alerted me to the water/oil problem :)

Old pump was worn so I replaced it a few months back. When I replaced the thermostat bolts after fitting it all back together I sheared one off.  Taking the 'stat cover off revealed lots of lovely, brown milkshake instead of water.

I think this issue is resolved now, but it might be a while before we get to check properly now.

 

 

If the fire was pin pointed to the starter motor, was it a damp day or are you aware of the age and state of the connections on the starter motor at all before the fire?

 

I think it was a little damp yesterday morning, and the connections would have been both a few years old and possibly in poor condition - haven't had chance to check all connections yet but we've had a few problems with bad wiring since buying the car last year.

So the theories make sense so far.

 

Any further symptoms I should be looking for when I get the grille taken off?

 

And is there any risk of any horrific internal engine damage?  This was my nightmare when I was thinking about it on the drive to work this morning :)

 

Thanks so far folks

[robminibcy]

Hi welcome to the club! My car did. Almost exaclty this only while driving Down a country road at rush hour in the dark and freezing fog! Although obviously too late now the starter motor staying on could be more simply down to the ignition switch not quite springing back to switch the starter motor off. One nice thing for you now is that you will have to fit a new loom which I found to be one of the most satisfying and enjoyable jobs I've ever done to it! You will also have no more previous owner syndrome or simply dodgy connections. In my opinion any mini being restored should get a new loom because it just saves so much hassle in the day to day running of them. Another possible cause of the fire could be what caused my fire which is where wires have rubbed against part of the car for several years and finally gone through to the metal ( in my case the lead from the alternator on the dipstick). There won't have been any damage caused to the engine but keep an eye on your battery and alternator for a while. Mine survived ok and any other circuits will most likley be unaffected due to the short and hopefully any additional accessories will have been correctly fused!

[Dan]

  I have to say there are about 2 dozen possible causes of a wiring fire that are more likely than damp air being responsible.

[mini maniac]

  I have to say there are about 2 dozen possible causes of a wiring fire that are more likely than damp air being responsible.

 

I'm not saying it is THE fault, just quite a likely one considering the time of year and all..

 

Maeith is just looking for the possible responsible parts and I was always told to start with the most likely scenario for the symptoms. From that a process of elimination to find what was actually the cause.

 

If you have any useful info of what to look out for i'm sure he would greatly appreciate it.

 

Switz

[Dan]

  Well I think it's been said, it's far more likely to be a physical problem with the solenoid or the ignition switch.  A short across the solenoid could be caused by a large buildup of dirt, which would be more conductive in damp conditions, but a largely clean one isn't gong to short because of wet air.  to be honest it would be unlikely to short if it was sprayed with a hose, the plastic is hydrophobic.  It's the same with ignition systems.  It's the wet oil and dirt that shorts out in wet weather, not the wet plastic.

 

  The extent of the damage to the loom will be a big clue as to what failed, but you can easily start testing components with a meter.

 

  I'm afraid I can't see a link between oil in the water and a failed water pump either, what makes you think that it could be?

[maieth]

1 - with recent work on the engine, stray splashes of oil across the connections is a possibility.

2 - Having chatted at more length with the missus about yesterdays events she say it was a lot of steam, the kind of cloud you'd get with an engine boiling over, immediately followed by the grinding noise that caused her stop, and then she had the problem getting the engine to cut out. The fire was several minutes later.

 

Going with the 'damp air' theory, surely a big cloud of water vapour blasted into the engine bay could be a contributing factor to the connections shorting out at the solenoid?  Without understadning this part of the engine thoroughly couldn't this have caused the solenoid or starter to short and then to sieze, creating the grinding noise, and then continuously turn causing the engine to keep starting and running, eventually overheating the cables and connections?

[Alex_B]

The white smoke from a starter motor burning out could have also looked like steam

[miniman24]

Another reason that I have a battery cut off switch - anything like this happens and you can cut all power off very quickly, limiting the damage (hopefully). A worthwhile addition IMO, good luck getting her running again.

[Dan]

  The solenoid will smoke lightly for several minutes before it actually catches fire.  Solenoids are not designed for continuous duty and will start smoking if you simply keep the key turned for more than about 45 seconds.

[Ethel]

Was there any click before the engine restarted itself? It should disengage automatically as a result of the motor acting as a generator when it's driven by the engine & providing reverse current to the solenoid.

 

It could fail in 2 ways:

 

The solenoid sticks fully engaged, with the engine driving the motor. This would be more likely to generate enough heat for a fire. A broken mechanical part might be the cause & explain the noise.

 

The solenoid disengages, but an electrical fault tries to reengage it immediately. This  would offer the best explanation for the grinding noise. Electrical overload ought to track back up the operating wire (red/white or red/brown), and not effect the other starter connections. If it has a starter relay that'd be the prime suspect.

[maieth]

 

The white smoke from a starter motor burning out could have also looked like steam

I thought this. Wife is convinced it was steam, but I can't comment either way. I figure if smoke had been building in the engine bay with the car in motion, it would have mostly risen at once when she stopped at the end of the road (where she noticed it and tried to kill the engine).

 

 

 

Another reason that I have a battery cut off switch - anything like this happens and you can cut all power off very quickly, limiting the damage (hopefully). A worthwhile addition IMO, good luck getting her running again.

Good call, planning to look into this, especially with a previous electrical incident.

 

 

Was there any click before the engine restarted itself? It should disengage automatically as a result of the motor acting as a generator when it's driven by the engine & providing reverse current to the solenoid.

Good question, that I don't know the answer to.  Not sure she'll remember but will ask.

 

Electrical overload ought to track back up the operating wire (red/white or red/brown), and not effect the other starter connections. If it has a starter relay that'd be the prime suspect.

I'll keep this in mind when I check the wiring over. Torrential rain all yesterday evening so hoping to look it over tonight now we have a little sunshine.

 

If I can, I'll put up some pictures of the damage later, see if that makes a diagnosis easier.  Ideally I need to get things fixed this weekend, or at least pick up the right parts.

 

Thanks for all help and ideas so far