Strange Smell from Vents

[Mattstorm]

Here is a strange one!

A bit of a querk from my Mini Cooper R56. After my car has been sat unused for a couple of days over the weekend (not used since 4pm friday) I get in to go to work on Monday morning. After driving 4 miles I have to stop at lights. Through the vents I get a strange smell, a little bit exhausty but slightly sweet it then passes as I drive off, this happens every time I stop but gets fainter. By the time I get to work and stop its virtually cleared, then thats it for the rest of the week till the following Monday. I've checked all fluid levels, nothing appears to be leaking. Its been into Mini and they can't see anything, the car runs 100% normal. Its like something builds over the weekend???

Any Ideas??

[BRGJCW]

A bit from left feild but it can be cat wee - used to get that when the car sat in the carport - warm bonnet attracts the pesky vermin and they piddle down the vents.....

It's only when you start moving and the airflow runs through the car that you get a whiff...

[Mattstorm]

I can't say I've ever seen a cat near my car when its on the drive and its every Monday morning after the car has been sat all weekend. Its very weird, it does smell slightly like exhaust fumes but when I get out and smell the back of the car it doesn't smell at all and the engine bay doesn't smell weird. I would have thought an exhaust leak would stink out the engine bay too. I take it the grill under the bonet but not inside the engine bay, the one just below the window on drivers side is the air intake for the cabin. I'm wondering if its my fancy shampoo that getting soap suds clogged and drying inside as I wash it every Sunday. The soap can get under the bonet to this grill as its outside the rubber seal of the engine bay.

[Mattstorm]

OK, so still not solved! Got a slight wiff yesterday and quickly popped the bonnet, looking directly at the engine block and sticking my nose in to the left hand side of the engine unit for a split second I thought i got a wiff there! But as usual with this issue it lasts for a couple of seconds then clears giving no time to really locate it! Fluid levels still normal, car runs normal????? Any Ideas.

[Angib]

Look on the bright side - at least your Mini bonnet locks. The 'amusing jape' played on a colleague in the 1970s to celebrate his wedding was to drop a kipper down the back of his battery - a week into his honeymoon touring Scotland (Munroe-bashing on yer honeymoon, can you believe it?*) they were nearly driven mad.

* He was a Methodist lay preacher, so it kinda fitted in.

[BRGJCW]

Still reckon it's animal related....

[SteveM3]

You can get an aircon cleaner. This is a bomb that goes inside with the aircon set to recirculate. This kills the bacteria that can grow in the pipes of the aircon/heater system. This is probably a last resort as I would have expected the dealer to be able to diagnose this.

[stead34]

Could it be a small coolant leak on the heater matrix that quickly evapourates when run. This would be hard to tell though unless you can expose it, customers used to describe this fault as a strange curry smell sometimes present in the car...

[Mattstorm]

I cant say it smells like curry. Its intermittent, I thought I had it linked with the car being left for 2 days unused, then maybe moisture ingress to the vent system, it was fine this morning untill I got to work then noticed a very faint wiff, this is 13 miles, would have thought it would have evaporated way earlier if it was a little leak. I keep checking under the bonnet before setting off to look for any moisture on any part which gets hot and can't see anything. Its going into Mini tomorrow morning but I'm not confident it will make the smell when I want it to so fingers crossed. I had thought about the air con bomb but I don't use the air con very often and I get the smell when the aircon is off.

[stead34]

It can be worse not to use the aircon that often as this can cause any stagnant water to turn bad in the bottom of the airbox, if you run the aircon then it will flow water through aiding the removal of this. The airbox cleaner kills the bacteria, so if the dealer cant find anything its worth doing this anyway as it should be done every so often so its not wasted money..

[Mattstorm]

My Mini went in last Friday and there were no faults on the car and everything looked normal so still not solved. Left the car all weekend until this morning (Monday) and the smell returned really quite strong after 2.5 miles of driving. As soon as the smell came I pressed the recirc button and the smell went away, pressed it again to turn off and it came back??? So its not within the vents system so its external. Going to book it back in to be left at the dealer for 2 days untouched so hopefully they will smell it on the Monday morning when tested???

[Mattstorm]

Ok, so the Mini went in Last Friday and was left until Monday, Mini tested it and apparently no smell, typical although hard to accept! They Air Con bombed it to freshen and kill bacteria and I picked the car up on the Monday night. Tuesday morning and what a surprise a faint whiff over the powerful air con bomb fragrance. So not solved.

Its not bacteria, fluid loss, coolant smell, burning oil smell, exhaust gasses, PCV (I asked this to be checked). Whats left????? I have a theory it can be either a slightly binding on brake caliper or parking brake shoe which is not seizing on but is touching and creating this smell. So the next test is to leave the parking brake off all weekend and see what happens, if it still occurs then it could be a caliper, not sure how to test this!

Any Ideas?

[stead34]

Fell the wheel area see if any are hotter than the others after a run, or you can jack it up and see if they arent binding

[Mattstorm]

Just to conclude this thread. We don't know. Had a Mini Engineer come to my house on Monday morning so I could drive the car after it had been sat all weekend so he could acknowledge the smell. Drove the car for 2 ish miles, came to a stop and nothing.... then a faint trickle.... built a little to an amount that I was easily picking up but was faint compared to most mondays. The Engineer couldn't smell anything, S0d's law! Its never been that faint before when its occured. I'm hoping it is fading gradually over time, whatever it is!!! So Mini probably think I'm off my trolley so game over, will put up with it or sell the car

[Mattstorm]

Update:

Problem still occuring, no real change in terms of strength or when it happens. Going to pick up a Charcoal Activated Filter from Mini later today to see if that atleast stops the smell entering the car as the car has now been chacked 6 times (I lose count) and mechanically its perfect so its not a problem as such. I think it might even be the normal smell of the engine which somehow is getting through to the cabin intake, maybe a seal not quite where it should be. Will wait and see if the filter is going to solve the issue. Love the Mini but the quality leaves alot to be desired in certain areas! Will still buy another one though next time !