Funny exhaust smell
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
Funny exhaust smell
2011 GL550 with 90k miles .. new plugs and filters at 80k.. Got out of the GL today after running 50 miles of errands and the driver side exhaust has a burnt toast smell and it is definitely the exhaust smell itself while the passenger side has a little oil smell. When I changed the plugs everything looked great.. no engine codes or lights on?
Any thoughts or similiar experiences? Thanks Bill
Any thoughts or similiar experiences? Thanks Bill
Thread Starter
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Joined: Jul 2016
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
burnt toast smell
I am concerned more about the burnt toast smell . I am going to hookup and read the voltage readings from the catalytic converters O2 sensors . I am concerned about the converters possibly blocking. Also the car has only been driven once in the last two weeks while I had Covid????
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NGL450 w/EORP, S550
Italian tuneup - then read codes. The cats about to be clogged, getting them really nice and hot and blowing the carbon out might rejuvenate them. Of course, if the core matrix is melted, that might be the smell.
That is of course that you don’t have any other significant mechanical damage going on that will grenade the engine at 6000 RPM.
That is of course that you don’t have any other significant mechanical damage going on that will grenade the engine at 6000 RPM.
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Mercedes gl450
I wouldn't call burning oil a "funny" smell. Nor would it likely only come out of one exhaust pipe if the engine is burning oil.
Maybe some fluid or piece of plastic landed on the exhaust pipe. Generally, they will check/top off fluids when you bring the car in for service. It's possible they spilled something that landed on the exhaust pipe or manifold.
Maybe some fluid or piece of plastic landed on the exhaust pipe. Generally, they will check/top off fluids when you bring the car in for service. It's possible they spilled something that landed on the exhaust pipe or manifold.
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
service
I wouldn't call burning oil a "funny" smell. Nor would it likely only come out of one exhaust pipe if the engine is burning oil.
Maybe some fluid or piece of plastic landed on the exhaust pipe. Generally, they will check/top off fluids when you bring the car in for service. It's possible they spilled something that landed on the exhaust pipe or manifold.
Maybe some fluid or piece of plastic landed on the exhaust pipe. Generally, they will check/top off fluids when you bring the car in for service. It's possible they spilled something that landed on the exhaust pipe or manifold.
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Joined: Jul 2016
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
No codes yet
Italian tuneup - then read codes. The cats about to be clogged, getting them really nice and hot and blowing the carbon out might rejuvenate them. Of course, if the core matrix is melted, that might be the smell.
That is of course that you don’t have any other significant mechanical damage going on that will grenade the engine at 6000 RPM.
That is of course that you don’t have any other significant mechanical damage going on that will grenade the engine at 6000 RPM.
First going to go with a Moly product and than Cataclean later in the week. Will read the voltages on the sensors next week.
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Thread Starter
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Joined: Jul 2016
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
Great tip
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'13 s212 63 p30. '06 LX470
No codes yet but definitely some bouncing O2 sensor voltages on the outboard side especially the driver side that has the burnt toast smell… this all came on suddenly ? Car was driven once in two weeks and the burning smell was the second drive in two weeks. No codes yet?
First going to go with a Moly product and than Cataclean later in the week. Will read the voltages on the sensors next week.
First going to go with a Moly product and than Cataclean later in the week. Will read the voltages on the sensors next week.
Generally the smell of bad cat is likened to eggs or sulphur. Burnt toast would be more likened to carbon, or oil issues.
You said the plugs were good, were they all dry?
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
plugs
I would not add the moly until after this issue is figured out. I do support something that can help clean the cats, something like a pea fuel additive and high rpm.
Generally the smell of bad cat is likened to eggs or sulphur. Burnt toast would be more likened to carbon, or oil issues.
You said the plugs were good, were they all dry?
Generally the smell of bad cat is likened to eggs or sulphur. Burnt toast would be more likened to carbon, or oil issues.
You said the plugs were good, were they all dry?
Watching some youtube videos I am going to run some cleaner and see if that stabilizes the outboard side .
Since I have barely ran the car for two weeks tomorrow I am also going to search for any rodent nest??? It would not be the first time in my garage that mice found a new home????
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
Thread Starter
Super Member
Joined: Jul 2016
Posts: 701
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
MBWorld Fanatic!
Joined: Jun 2014
Posts: 1,085
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
MBWorld Fanatic!
Joined: Jun 2014
Posts: 1,085
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
Sorry its taken a few days. Here are screenshots of my ML550 data. Cat temps at 394 degrees C on both sides, noting a very hot day here with tempreture about 37 degrees C. Car was at operating temp after a drive and engine was running when the data was taken. There's a bit of double up in the data as they were taken from different screens that sometimes duplicate information. Hope this helps.
Last edited by BlackML550; Feb 3, 2025 at 12:40 AM.
Thread Starter
Super Member
Joined: Jul 2016
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
thanks
Sorry its taken a few days. Here are screenshots of my ML550 data. Cat temps at 394 degrees C on both sides, noting a very hot day here with tempreture about 37 degrees C. Car was at operating temp after a drive and engine was running when the data was taken. There's a bit of double up in the data as they were taken from different screens that sometimes duplicate information. Hope this helps.
Thread Starter
Super Member
Joined: Jul 2016
Posts: 701
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
Going south
Not going very well as a few predicted it might go south. On startup today it threw 5 codes
P0300…P0303 cylinder 3…P0304…P0306…P0307…
Hookup the Icarsoft and cleared them .. not coming back on yet but running very on the catalytic exhaust… let it high idle at 3000 rpm in the driveway and it reached over 1000 f …. definitely having catalytic issues… any thoughts… thinking of putting it on a lift tomorrow and putting a camera into the converter’s ????
P0300…P0303 cylinder 3…P0304…P0306…P0307…
Hookup the Icarsoft and cleared them .. not coming back on yet but running very on the catalytic exhaust… let it high idle at 3000 rpm in the driveway and it reached over 1000 f …. definitely having catalytic issues… any thoughts… thinking of putting it on a lift tomorrow and putting a camera into the converter’s ????
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From: Melbourne, Australia
2010 ML550 VIN WDC1641722A564750, 2010 B180
Just wondering now - if the cats are stuffed, you'd imagine:
High cat temperatures
Large variance between before and after O2 readings with the after cat reading should be stable and in theory shouldn't fluctuate.
Heat - in theory the after cat tempratures should be higher than before cat temps, so if theyre blocked, they should theoretically be lower after the cat with more heat mid-cat. Maybe a temperature gun to read the temps?
I've read (but not seen) that a pressure test can be done before and after the cat by removing the O2 sensors and using the bungs as the access points. If they're blocked, you'd expect much less pressure after it, but I've got no idea what the differential would be. Hope this helps.
High cat temperatures
Large variance between before and after O2 readings with the after cat reading should be stable and in theory shouldn't fluctuate.
Heat - in theory the after cat tempratures should be higher than before cat temps, so if theyre blocked, they should theoretically be lower after the cat with more heat mid-cat. Maybe a temperature gun to read the temps?
I've read (but not seen) that a pressure test can be done before and after the cat by removing the O2 sensors and using the bungs as the access points. If they're blocked, you'd expect much less pressure after it, but I've got no idea what the differential would be. Hope this helps.
