White smoke (vapour?) on startup PANIC! Please help

[MasteringGuy]

The initial message was deleted from this topic on 29 July 2024 at 17:13

[TimmyMallett]

Has it rained recently or have you washed it? Could just be condensation. If it goes away I wouldn't worry. Unless it does it all the time......if its under warrant go get the coolant tested.

[mike-v2tmf]

Condensation, plain and simple

[anonymous-user]

Just return it and pick something else off the forecourt.

[littleredrooster]

Bear in mind that when a gallon of petrol is burnt, about a gallon of water is produced. This shows as water vapour when the metal bits are cold, and as steam (which is invisible) when everything is up to full temperature.

[ApexCult]

mike-v2tmf said:

Condensation, plain and simple

Won't help if the car has been sitting around a dealer only getting started and moved very short distances

[Krikkit]

It's fine

[legless]

On some cars, the exhaust seems to be great at trapping condensation.

My old Audi S4 used to puff water vapour like an old steam locomotive for a good few minutes after startup, every time. On a cold morning it would be enough to completely obscure my rear vision if the car was stopped. Nothing wrong with it at all though.

[GreenV8S]

MasteringGuy said:

There is an unidentified code, so I'll probably clear that

If you don't have the tools and knowledge to know what the code means you shouldn't be clearing it.

Water vapour from the exhaust is very common and may be normal for your car for the conditions. To be on the safe side I suggest you check the oil and coolant levels. Not that there's any reason for concern, but it's something you should be doing as a matter of course which would also tell you if you had a significant leak.

[cuprabob]

It's an emissions thing. To get the cats upto temperature quickly, modern petrol cars run secondary air injection (SAI) or adjust fueling accordingly for a short period after start up, under certain conditions.

[GreenV8S]

MasteringGuy said:

Apparently it's not recommended to let a Mazda 3 idle you are supposed to get a move within a minute regardless of outside temp.

That's common for most modern cars. Cold running is one of the worst situations for the engine and letting them warm up off load just prolongs the cold running. Far better to get some gentle load on the engine to get heat into it.

[paintman]

littleredrooster said:

Bear in mind that when a gallon of petrol is burnt, about a gallon of water is produced. This shows as water vapour when the metal bits are cold, and as steam (which is invisible) when everything is up to full temperature.

I've said this time & time again.

This condenses inside a cold engine and a cold exhaust and is the main reason for cars that only do short trips going through exhausts faster then those that do distances - they never get hot enough to boil the water off and they rot from the inside out.

Also manifests as mayo in the oil filler cap & I wonder how many have had their trousers pulled down by the unscrupulous claiming it's a sure fire sign of hgf and paid for work as a result.

Will only appear worse as the weather gets colder - bit of a 'No st Sherlock'!

If you aren't losing coolant then you don't have a coolant related hgf.