audiophool

2008 535xi.

I was waiting in the gas line at Costo the other day and had been idling for a few minutes. You know how long Costco gas lines can be, but heck, if I can save $10 on a tank I'll spend a few minutes.

It's a bit below freezing and all the cars around are spitting steam out the exhaust as usual, but I suddenly noticed there was steam coming out of my grille. Opened the hood and there was a fair amount of steam in the engine bay. Cooling fan was cycling normally. I shut off the engine and waited until I could pull up to the pumps.

After filling, re-started and the steam was still coming out. I pulled across the parking lot and called AMA for a tow.

Got the car home and by that time the engine was cool so I checked and the coolant reservoir was full. Idled it for 15 minutes or more in the garage and no steam. No wetness anywhere I can see either.

Yes, the roads were wet/slushy, but I don't think I picked up anything that was melting/steaming on a hot engine.

Time to take it for another drive and see if it repeats.

bellabmw

Check the water pump if you see any leak usually before they fail they start to show steam.

seanjordan20

When I had that issue a few years ago it was oil leaking I believe the oil filter housing

H F

Its the difference in the out side temperature and the hot coolant temperature cycling thru the radiator . The heat in the coolant escapes on the fins in radiator and thus releases steam once the heat escaping hits the zero cold temp .

Have you ever seen a football player with a hot and sweaty bald head remove his helmet in really cold temperatures ? Steam will rise off his head ..

audiophool

^ an interesting idea, but in order to produce steam, the heated radiator fins would need to be wet.

H F

Zero degree cold air moisture will produce enough for it to happen , when it hits the hot fins ..

FormerE30Owner

The dew point of the air would have to be at 0 degrees also (i.e snowing). Air moisture will not condense on the hot fins and cause steam, but snow or freezing rain might, OP stated that it was just below 0. and not precipitating. I suspect some built up snow in the cabin air filter area melting dripping off the hot engine or exhausts,

Kind of ironic having a Californian telling an Albertan about winter or cold weather phenomenon.

H F

Doesn't have to go as far for moisture to condense and settle on the fins . The cold humidity and moisture in the air just has to hit the hot fins and it can happen ..

What happens when you blow warm air out of you're lungs and that warm breath of air hits the super cold weather ?? Same principle .

This is not a extraordinary phenomenon ,, there is plenty of information of this happening in cold weather,, with out rain and snow . And you don't exactly have to be a Albertan or a eskimo to know or read about it .

FormerE30Owner

Perhaps not, but it does help to be an engineer who understands condensation and vaporization. There has to be some liquid water on the fins for the hot fins to vaporize and then cause visible steam. Moisture in the air doesn't condense on the hot fin then vaporize.

With respect, Bob P.

alfa_romeo55

H F is giving you the scientific approach or in Laymans (sp?) terms real life diagnosis to the steam coming from the engine and some of you are are trying to suggest he is wrong....Read what he has to say and apply it to whats happening......I dont understand why the attack on HF.... HF, I'm with you. Thanks for the clarity and taking the time to respond.