e90 M3 strong exhaust

mrh335 · 11-08-2021, 09:57 PM

I have a 2011 e90 M3 that is completely stock.

Recently I had an oil leak and oil smell and very strong exhaust smell.

The valve cover gasket was replaced three times to fix the oil leak hopefully for good. The exhaust manifold gaskets were replaced last year due to a very small leak.

The exhaust smell still remains. When sitting at a traffic light, the smell is so overwhelming in the car, I need to open the windows. It is bad when the car first starts, when it is returned warm to the garage, or when idling. The exhaust system has been inspected and no leaks found, but there has to be something huge. I am the only owner and never has the exhaust been this strong and it noted by my wife as well as being awful.

Does anyone have any suggestions of where to hunt for this issue and what the cause could be?

chutak · 11-09-2021, 04:27 AM

Check if the small donut gaskets are installed and not falling apart at where the headers connect to the primary cats. Also, ensure the torx bolts at that connection are tight, should be torqued to 20 ft-lbs. An exhaust leak at this location can be quite smelly.

nrubenstein · 11-09-2021, 11:15 AM

Do you have excess exhaust noise? An exhaust leak of the scale that you're describing would be catastrophically loud on the S65.

Frankly, the symptoms that you describe sound a lot more like oil dripping on your exhaust than an exhaust leak. Did they replace your valve covers, or just keep replacing the gaskets?

mrh335 · 11-09-2021, 12:55 PM

Quote:

Originally Posted by nrubenstein

Do you have excess exhaust noise? An exhaust leak of the scale that you're describing would be catastrophically loud on the S65.

Frankly, the symptoms that you describe sound a lot more like oil dripping on your exhaust than an exhaust leak. Did they replace your valve covers, or just keep replacing the gaskets?

They replaced the gasket only. Some paint was chipping on the covers which may have been the culprit leading to multiple failures, but they cleaned up the sealing surface to help with that. That was last week and the exhaust smell is same before and after that fix.

I haven't noticed any change in exhaust noise in the car. My wife says it sounds different from outside, but not sure how accurate that is.

Kman987 · 01-18-2022, 04:07 AM

hi mrh335! Did you resolve your smell problem? I am dealing with what seems like the exact same problem. Faint smell of exhaust fumes when the car is moving, which becomes uncomfortably bad when the car is running stationary at a light. As I am typing this, just having a though...I should prolly crank up the AC immediately after starting the cold starting the car to see if its oil dripping on exhaust headers problem.

In any case, please chime in with the status of your problem.

Cheers,
Kman987

mrh335 · 01-18-2022, 10:24 AM

Quote:

Originally Posted by Kman987

hi mrh335! Did you resolve your smell problem? I am dealing with what seems like the exact same problem. Faint smell of exhaust fumes when the car is moving, which becomes uncomfortably bad when the car is running stationary at a light. As I am typing this, just having a though...I should prolly crank up the AC immediately after starting the cold starting the car to see if its oil dripping on exhaust headers problem.

In any case, please chime in with the status of your problem.

Cheers,
Kman987

I don't have a solution yet. I was crawling around the engine this weekend and was able to determine the smell is more oil than exhaust. The tail pipes have no fumes at all. When the hood is open, the smell is very strong near to the hood air intake area. The other side of the engine does not have a smell. Looking a little deeper, I can see some oil residue on the exhaust shield bolt recess below the valve manifolds. I am going to monitor and check that now to see if it is old oil that keeps smelling or if there is still an oil leak dripping in that area or if it is something completely different I haven't found yet.

CamasM3e93 · 01-18-2022, 12:15 PM

I'd say you are burning leaking oil falling onto the exhaust header rather than an exhaust leak - based on your observations and what else is going on. Are you getting any fouling of dirt/grime around either of the oil separators? these are black plastic devices that come off the valve covers and connect up to the plenum. you can get leaking of oil around the base or where they connect to the plenum. I solved the leak by replacing the gasket on each of side and scraping away the chipping paint layer on the valve cover where the gasket sealed - so I had bare metal all the way around where the oil separator gasket sits against the valve cover. My mechanic thought it was a leaking valve cover gasket and it was actually this - so if you've gone through 3 valve cover changes maybe they missed the source and you've got oil leaking down onto the exhaust header.

11-08-2021, 09:57 PM	#1
mrh335 Second Lieutenant 28 Rep 207 Posts Drives: 2011 M3 sedan, jet black Join Date: Oct 2006 Location: Bay Area iTrader: (0)	e90 M3 strong exhaust - stock I have a 2011 e90 M3 that is completely stock. Recently I had an oil leak and oil smell and very strong exhaust smell. The valve cover gasket was replaced three times to fix the oil leak hopefully for good. The exhaust manifold gaskets were replaced last year due to a very small leak. The exhaust smell still remains. When sitting at a traffic light, the smell is so overwhelming in the car, I need to open the windows. It is bad when the car first starts, when it is returned warm to the garage, or when idling. The exhaust system has been inspected and no leaks found, but there has to be something huge. I am the only owner and never has the exhaust been this strong and it noted by my wife as well as being awful. Does anyone have any suggestions of where to hunt for this issue and what the cause could be? __________________ 2011 E90 M3 Jet Black/Black ZPP, ZCP, ZTP, ZCW, 6FL, PDC, shades, 6MT
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11-09-2021, 04:27 AM	#2
chutak Second Lieutenant 207 Rep 242 Posts Drives: E90 M3, X3 M40i Join Date: Apr 2015 Location: NoVA iTrader: (1)	Check if the small donut gaskets are installed and not falling apart at where the headers connect to the primary cats. Also, ensure the torx bolts at that connection are tight, should be torqued to 20 ft-lbs. An exhaust leak at this location can be quite smelly.
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11-09-2021, 11:15 AM	#3
nrubenstein Captain 567 Rep 801 Posts Drives: E30 M3/E36 M3/E46 M3/E90 M3 Join Date: Dec 2016 Location: Washington, DC iTrader: (2)	Do you have excess exhaust noise? An exhaust leak of the scale that you're describing would be catastrophically loud on the S65. Frankly, the symptoms that you describe sound a lot more like oil dripping on your exhaust than an exhaust leak. Did they replace your valve covers, or just keep replacing the gaskets? __________________ 2011.75 E90 M3 \| 2006 GMC Sierra LBZ \| 2004 X5 3.0i 6MT \| 1995 M3 S50B32 \| 1990 325is \| 1989 M3 S54B32 Hers: 1996 911 Turbo \| 1989 325iX
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01-18-2022, 04:07 AM	#5
Kman987 New Member 0 Rep 7 Posts Drives: 987 Porsche Cayman S Join Date: Jan 2018 Location: Baku, Azerbaijan iTrader: (0)	hi mrh335! Did you resolve your smell problem? I am dealing with what seems like the exact same problem. Faint smell of exhaust fumes when the car is moving, which becomes uncomfortably bad when the car is running stationary at a light. As I am typing this, just having a though...I should prolly crank up the AC immediately after starting the cold starting the car to see if its oil dripping on exhaust headers problem. In any case, please chime in with the status of your problem. Cheers, Kman987
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01-18-2022, 12:15 PM	#7
CamasM3e93 Friends don't let friends ESS 3140 Rep 862 Posts Drives: '11 Lemans Blue 6mt Harrop e90 Join Date: Dec 2020 Location: Camas, WA iTrader: (0) Garage List 2011 E90 M3 [9.00] 2003 Porsche 911 Turbo [9.75] 2019 BMW X5 xDrive40i [0.00] 2013 Mercedes E550 ... [0.00]	I'd say you are burning leaking oil falling onto the exhaust header rather than an exhaust leak - based on your observations and what else is going on. Are you getting any fouling of dirt/grime around either of the oil separators? these are black plastic devices that come off the valve covers and connect up to the plenum. you can get leaking of oil around the base or where they connect to the plenum. I solved the leak by replacing the gasket on each of side and scraping away the chipping paint layer on the valve cover where the gasket sealed - so I had bare metal all the way around where the oil separator gasket sits against the valve cover. My mechanic thought it was a leaking valve cover gasket and it was actually this - so if you've gone through 3 valve cover changes maybe they missed the source and you've got oil leaking down onto the exhaust header.
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