X3 went bang.
 

wife driving her X3 when loud bang heard followed by white smoke from left exhaust,30i auto 2004.I arrived on scene,removed oil filler cap to see yellow gunge,suggesting water mixing with oil,but car used for short journeys last week during cold weather could cause gunge.or head gasket could be leaking,will remove spark plugs tommorow to see if any contamination,do compression test,do coolant sniff. tested crankcase vent valve by checking vaccum at oil filler,seems ok. I wonder if anyone could confirm suspected fuel injector sticking open as causing smoke and slight rough running. any suggestions welcome. will have diagnostics tommorow.:(:dunno:

Definitely sounds like something caused a backfire. Any of the yellow oil/water sludge on the dipstick?

Hi weasel 56 x, thanks for quick response,dipstick ok,oil looks ok,wife stopped as soon as fault happened,car has 40,000miles,service due in 600miles,car never abused.she had music playing loud so bang sounded like big misfire that made me think of overfueling,but engine management designed to overfuel under certain circumstances.car run 40 mile round trip yesterday,same route today only got 32 miles until fault. started engine four times since and always get lots white smoke,smells bad.coolant level ok.

Does it smell more like burning oil, coolant or rich with gas?

Hi weasel 56 X,thanks for quick reply,dipstick clean, oil looks clean,car has 44,000miles, service due 600miles,car never abused.wife had music playing loud so bang was like big misfire followed by white smoke,she stopped quick.coolant seems ok.car started 4 times since fault,runs slightly rough,lots white smoke, smells bad .i understand engine management designed to overfuel under certain circumstances. She just told me that car was revving higher than usual pulling up hill around 3000 rev then shifted up gear on auto when misfire occurred.

I thought i had accidently deleted reply, so typed another,,,oops,smoke smells like it could be all three,but i initially thought it more like damp wood burning ,does not smell like rich fuel mix,wife thought inside car was on fire as smell like material burning.

Hopefully the diagnosis turns up something minor and easily fixed. I'll be curious as to what happened myself!

Yes, i shall post as soon as i find cause,i just hope it`s a minor fault and not cylinder head.heavy snowfall starting here now, so may have issues fixing car quickly,she aint getting my X5 4.4 in this weather.

HERE IS THE CATALOGUE OF INCOMPETENCE SO FAR- sunday 14.30, problem with car,call bmw emergency service,16.00,contract recovery arrives and decides to dump car at home 4 miles away rather than take to stealer 14 miles away,says someone will come back at 08.30 next day, did not arrive,- many calls to bmw-much bullshit- - 10.30 tuesday-other contract recovery arrives,--17.30,-rental car arrives,-wife missed 2 days work, kids missed 2days school. - wednesday 09.56,stealer calls to say cannot find any problem-i tell them again what i told when booking car in that sticking injector or crank vent oil separator broken.--16.00-dealer says oil separator-need to order part--WATCH THIS SPACE.:yawn:

What a dissaster...That dealer sounds awful...And who even knows if the Oil seperator was the actual reason why your car made that loud noise? It doesn't sound like they found the real problem per say..