1st Gen R53 Cooper S Most liked posts in thread: What am I smelling when I stomp on the gas?

last night I went for a spin and decided to do a little research on the smell thing. Since the last hard pull the car has been driving around town a few times, maybe 40 miles total of short and easy trips, so it was time to clear the pipes again.

First pull was 2nd gear, full throttle up to about 55k rpm at 14.5psi boost. The roof was cracked open and we were headed into the wind. The smell that got into the cabin was so strong we had to open the windows. My son said that a few weeks ago when we drove home from Road America, his friends who were driving behind us also smelled it. Conclusion from all that - the smell comes out of the exhaust and depending on turbulence, speed, open windows, gets sucked into the car. Scary to know that some exhaust fumes actually get into the car even when every window is closed, but there's no other explanation. If we had such an exhaust leak for fumes to come from the front of the car through the hood to the fresh air intake, that would be audible.

After the first pull, we did a few 6psi runs with less throttle. No more smell. Next open stretch of clear road, one more hard pull at full throttle and boost in second gear, almost exactly like the first one, but in a different direction to the wind, and no smell.

I figured if this is a leak in the intake system, rpm should not matter, but boost should, so we did three more pulls in 4th and 5th gear full throttle from lower RPM, boost at 10-11psi, climbing slowly with the rpm building before lifting. No smell. One more hard pull to 6k rpm, and again, no smell.

Conclusion - crap builds up on the IC surfaces or other areas of the intake, and if not driven hard for a while, the first hard pull will suck much of that gunk into the engine, it burns the oily mess and what we smell is a puff of smoke coming out of the exhaust.

So for next season, I've added a catch can to the shopping list. The smell clearly was "exhaust flavor" with a blend of some real icky stuff in it, probably exactly what come out of a crank case and builds up in the IC. Everyone who ever smelled it agrees that it doesn't smell like rubber, just some real rank exhaust.

 

ah yes, every time my Mini does some weird stuff no other car does, I am told my damper is probably failing. When the engine cuts out completely without engine code on a long uphill mountain road, I am told I am screwed and it must be the damper self destructing. Now I smell combusted dinosaur juice in the cabin and it is could be the engine damper failing...

Can you even remotely explain what the damper has to do with the smell in my cabin after a brief pull to maybe just 3500rpm?

I've thrown $400 at the damper failure risk and put an ATE damper in there this summer, only to remove a perfectly fine OEM damper. The car smelled like this before the damper change, before several oil leak fixes, before new belts and tensioner, although that lasts bit probably is responsible for the lack of burnt rubber that used to be mixed in with the smell.

The car runs fine. The seals on the SC are fine, or at least I can attest there's full boost at full throttle (15 PSI). It stinks even on just 2 or 3 pounds of boost. I am not really asking how to keep the smell from coming into the cabin by sealing the hood. I know it is bent up slightly higher now by the M7 strut bar, so I guess that's why it is more noticeable than it was in the past.

The question is - what on earth is causing this? I want to exterminate the source of this. It does smell mostly like an exhaust leak under the hood, but it doesn't sound like I have that issue, plus I'd smell it all the time if it was a leak in the exhaust system.

My best guess is that there's some EGR fumes mixed into the SC pressurized part of the system and it leaks slightly under pressure, doesn't leak in normal driving, as then the intake runs a vacuum and everything gets sucked into the engine.

So where can it leak post super charger? The IC boots seem fine, but I can throw more money at the car and replace those, too. What about that bypass valve area - it does have some rubber parts to it that may not be sealed perfectly? Going to yank the SC this winter for another oil change, so I'll just replace all that stuff, too . That's been pretty much my mode of maintenance with this Mini: anything that has failed on other cars, just replace. Am I forgetting a soft spot in the pressure segment of the SC system that could leak?

Regarding keeping the smell out - I've soaked the hood liner material around the M7 bars the day I installed and then many more times, but the hood is still up a little in the center. I am thinking it may be time for a knife to be asked for some more aggressive assistance with the hood liner to get that hood back to a proper seal, but I did smell this stuff before the M7, just not s bad as now.

 

I thought it was something like burnt oil. Unlikely now, because after 2000 miles since fixing every oil leakI could locate, the engine is still shiny clean and there's really no oil anywhere on the outside of it. New valve cover gasket, O-rings on dip stick and CPS sensor are still holding, new crank seal on the damper side. No leaks visible.

The smell - how to describe?

It certainly isn't rubber, nor clutch/burnt slipping smell. It is like really bad exhaust pre-cat lightup, and maybe some burnt oil mixed into it. The car does not smell like that out the tailpipe. It is a little more on the burnt side, so oil is probably involved, but none of that oil is external on the engine block, nor would I think oil burns of so quickly in response to higher boost, but never when just cruising along. There's no oil leak around the exhaust ports that I can spot. Valve cover gasket was replaced in June.

Searching around, it appears many others have noticed this smell, but no real answer as to origin. Over at NAM there are a number of older threads about this. No answers, though.

Looks like I'll just address it over the winter - new gaskets everywhere, replace most of the exhaust system if the budget allows. Also, it isn't the end of the world. The car runs fine. Smells a little. I've had motorcycles with everything vented to the outside air and they were worse. In fact, thinking back to what that smell was like, I think the crank case smell from that modified KTM 950 engine was very similar to what I smell now.