Something not right - puff of smoke (OSF)
 

I've just seen a puff of smoke emanating from the driver's side front wheel (OSF) whilst waiting in traffic. My brakes aren't red-hot (checked and showing 45C on IR thermometer) and I was wondering if this is due to some seal that goes, inevitably leaking onto one of the front cats? My old A8 used to do this on a regular basis, but I've not experienced it so far in my A8L.

I always thought that it dripped on the nearside cat i.e. passenger-side but this puff of smoke came out of the driver's side wheel area. I'm sure some learned person will be along in a minute to allay my concerns... or tell me it's going to cost more money lol

Cheers all.

I suppose it could be a number of things but that's how my power steering hose failure started. There was also a strong smell, like burning plastic.

Not a coolant leak is it? :Confused:

Could be cam cover gaskets. There is an oil trap in the rear right hand corner of the right cylinder head so if the gaskets are dried up that corner drips on the exhaust manifold first.

There's also a cam oil seal blank in that same corner, but they don't tend to leak. Or of course the cam tensioner gasket - they can often leak and also drip on to the exhaust manifold.

If it was the gearbox that would usually show from under the car rather than as far forward as the wheels.

Doesn’t the rear output seal on the ‘box drip onto the o/s cat? IIRC, I had just that issue some years back.. MJ will know for sure! :)

Yes it does, but that is much further back than the wheel arch and would normally present itself as a bad smell rather than smoke. The description of smoke from the driver's side wheel arch says engine to me since that's typically where the V8 leaks - cylinders 4 and 5. If it were the passenger side I'd suspect power steering since an oil leak would usually drip on the power steering pump on that side, not the manifold.

I told you that The Doctor would know! :)

Thanks to all for the invaluable assistance.

I've just returned from Somerset and although I didn't see any puffs of smoke, I did smell something when I parked the car up just now. I'm sure it's not a coolant leak as I've only recently had the aluminium oil cooler union/connection fitted to replace the stupid plastic OEM part that cracks. My old A8 certainly had the issue with fluid dripping on the catalytic converter but this current problem doesn't smell quite the same though.

Some of you may already be aware that I had some rough-starting recently with an O2 sensor code but this hasn't come back to haunt me yet. Lumpy idle is still being experienced for the first 2-3 seconds after starting her up but it settles down to a solid 650rpm or thereabouts.

MJ's comments about cam cover gaskets / cam tensioner gaskets sounds likely -
I will allocate some time this week to pop down and see DS Autowerks in Crawley.