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Engine Bay Smoke On Start Up


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#1 s2ulk

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Posted 01 April 2024 - 04:21 PM

Hi all,

I’ve had my Mini (1999 MPI) parked up in a garage with battery disconnected since November. The car is new to me (bought in October) and it was running/starting fine when I disconnected the battery and put it into hibernation.

Went this afternoon and reconnected the battery (fully charged) and tried to start it. It was turning over very slowly/laboriously a bit like when the battery is almost flat. Then it fired with a loud squeal (timing belt I suspect) before smoke started billowing from the engine bay almost like there was an engine fire. I killed the engine and after a minute (once I’d moved my son well away!) I popped the hood. It was still smoking a bit but I couldn’t see a source.

I checked the oil which is low so looks like it’s leaked a fair amount when parked up. Otherwise there hasn’t been any change.

There was a small amount of fuel left in the tank from November.

Any ideas on potential cause?

I will set about changing oil, filters and draining remaining fuel and adding fresh fuel before the next attempt at a start in any event.

Thanks

#2 Stevie W

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Posted 01 April 2024 - 04:37 PM

Sounds like either the water pump or alternator may have siezed up. 

 

That would account for the slow cranking even with a full battery. When the engine did fire, the squeal you heard would be the fan belt slipping. This would may have caused the smoke you saw.

 

I would slacken off the fan belt off or remove it, then check to see if the water pump or alternator are siezed.

 

Hope this helps, cheers, Steve.


Edited by Stevie W, 01 April 2024 - 04:38 PM.


#3 KTS

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Posted 01 April 2024 - 04:38 PM


Quite possible the loud squealing and the smoke are related. Check whether the alternator is seized

#4 s2ulk

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Posted 01 April 2024 - 05:31 PM

Thanks both - that’s very helpful and sounds very much like the culprit. Is a seized alternator a replacement job or a repair?

#5 bpirie1000

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Posted 01 April 2024 - 05:35 PM

Smoke could just be condensation on the exhaust.. perfectly normal if it is just that

#6 Steve220

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Posted 01 April 2024 - 05:40 PM

Thanks both - that’s very helpful and sounds very much like the culprit. Is a seized alternator a replacement job or a repair?


Replace, they're only £90.

#7 Stevie W

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Posted 01 April 2024 - 07:15 PM

Thanks both - that’s very helpful and sounds very much like the culprit. Is a seized alternator a replacement job or a repair?

 

To be honest just replace the alternator with a exchange unit or buy a new one outright.

 

Cheers, Steve.



#8 Aly-g

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Posted 02 April 2024 - 08:51 AM

Just a thought, have you checked the water level ?, worst scenario could be leaking head gasket into the cylinders, this could cause the water in the cylinder to compress then the engine will not want to turn over or turn over with difficulty, did the car run OK when it did start ? Or was it running lumpy / rough ? Let us know how you get on.


Allan

#9 MatthewsDad

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Posted 02 April 2024 - 09:47 AM

What did the 'smoke' smell of? Steam, burning plastic, oil, electrical ?

#10 gazza82

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Posted 02 April 2024 - 12:05 PM

Remove the alternator belt and try and turn the alternator by hand. Then the water pump.

You could also try and restart it like that and see if it smokes again, but it does sound like something has seized and the belt was rubbing on one of the pulleys and overheating.

#11 Cooperman

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Posted 02 April 2024 - 01:24 PM

As above. Take the grill off then remove the fan-belt.
Check the alternator and water pump for free rotation, then start it with the fan-belt off and see if it still smokes. You can safely run it for a couple of minutes with the belt removed.
Make sure that the belt is fully tensioned after refitting.
Otherwise, could it be oil on the exhaust manifold from a rocker cover gasket leak?

#12 s2ulk

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Posted 02 April 2024 - 04:49 PM

Thanks for the replies all. It was thick white smoke and really was billowing out and filled the cabin too - smelt a bit like plastic/rubber. Reminded me a bit of the smoke you see when somebody does a tyre burnout and so the suggestions of the belt creating the smoke makes sense. I’m going to fit a new alternator - no harm in doing that especially as suspect it’s the original. Will fit a new fan belt at the same time. Is it worth replacing the water pump too? That has always been recommended when I’m changing the fan belt on other cars (although I have had a mechanic do those whereas I’m working on the Mini myself).

#13 lsto

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Posted 02 April 2024 - 05:31 PM

I'd run the car and look to see where the smoke is actually coming from then go from there. If your worried about starting it again then as above pop the belt off and check if the water pump and alternator turn. If they are not seized you could be spending a few hundred quid and a few hours grief and accomplish nothing. It'll take a couple of minutes to cut the belt off and check the pulleys if you don't want to unbolt anything, seems pointless just throwing bits at a car and hoping for the best. Spend a few minutes now and save yourself time and money.

#14 MatthewsDad

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Posted 02 April 2024 - 08:30 PM

As above advice, I'd do a few simple checks first starting with running without the belt. Process of elimination. If you do decide to replace the alternator you may want to check out small businesses that refurb them rather than buy a new unit. Cheaper option. I've used this guy near me several times over the years. https://www.alternatorsnorthwest.com/

#15 s2ulk

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Posted 03 April 2024 - 10:48 AM

Very sound advice - will run a check first by removing the timing belt. Cutting it off is of course straightforward but is fitting a new replacement belt difficult? I have looked at the relevant section of the workshop manual and it looks relatively straightforward but I’ve seen a couple posts where owners have struggled to get a belt refitted.




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