Smoke from bonnet in traffic

[DannyG]

So I was stuck on the motorway earlier due to an accident and was stationary with engine running and noticed occasionally whisps of smoke/steam drifting from the front of the car.

It was right at the front which suggests to me it's from the radiator area, temp gauge never budged from pointing straight up and it could have been my imagination but thought I smelt a bit of burning!

As soon as I turned the engine off it stopped. Could it be some crap caught around radiator burning when it heats up?!

[x DTR x]

Are you sure it wasn't coming from the exhausts of the traffic in front of you? Best thing is to leave it running away from anything and see if it happens again and then try to spot where it is coming from?

[DannyG]

It was definitely from the bonnet, I'd left a good 3 car gap for that reason, as I noticed it was still doing it when the car in front edged forward.

I think I'll give it a good run tomorrow and leave it in the drive with the engine running afterwards, see if I can see it happening again, and from where!

[dme123]

Was it raining or was the road wet? I've often noticed steam when the car is stopped in traffic in such conditions from the rain and spray evaporating off the radiator at the front. My MX5 is terrible for it, it looks like the rad has a hole!

[robertburnett1986]

If you leave it running and notice it again, pop the bonnet to see a) where it's coming from b) is there any smell to it ie. burning oil.

[Guru]

A probable cause which I've seen happen on another forum: A hair thin crack in the expansion tank causing coolant fluid to leak out and run down the hoses and then on to the radiator from where it starts to evaporate.

[DannyG]

It wasn't raining yesterday, but I have noticed it do that when stopped in rainy conditions and could understand that.

I didn't manage to get the car our for a drive today (and its bouncing it down) so will keep an eye out for it happening again in dry, and pop the bonnet!

[AndyMcc]

Start with basics. Expansion tap cap. Is it on fully and sealed ? Cracks in the tank ( would be surprised ) pipes leading away etc etc. if it was mine I'd run it until hot and then stop, rev it to keep / get the temperature hotter then lift the bonnet. That should point you in the right direction.

Good luck,
Andy

[Welton]

I had to replace my expansion tank at 60K miles because it split across the top.

I get steam coming off the rad when it's raining, it's quite normal but keep an eye on the coolant level and maybe put some plastic down on the floor under the engine bay at night, see if it catches anything.

[eric19371]

I know this is an old thread but I have noticed the same thing happen twice on my V50, with the second time being today while waiting to go into a local tip, so I thought I would search through the forums, and hey presto, two threads with the same issue and plenty of replies. No loss of coolant so must be water from rain or overnight condensation (lower area around airbox looked damp).

I love these forums !!