1984 500SEL strong exhaust smell outside and inside

[werminghausen]

My 500SEL has still a long to do list.
one of the top issues is the exhaust smell inside the car.
The smell of the exhaust is really bad when I am measuring transmission oil levels for instance with the engine running.... it is by far the worst smell of all my Mercedes cars. And I don't understand why that is.

conditions
The ignition and engine performance are as expected from a Euro spec car, very strong engine.
The exhaust system is in bad shape in general and I'll have to replace the downpipes soon. They are very rusted out and might be leaking exhaust. Exhaust manifolds could be leaky at the heads.
(Are exhaust downpipes available and other parts of the exhaust? Any aftermarket pipes you can recommend?)

I have a Euro car with no CAT originally. With the gray import to the US the car received a CAT/O2 sensor and the K Jet modifications etc. I already shut down the K-Jet modifications and the engine is running with the original K-jet system now.

The CAT is still in place where it was welded into the exhaust below the drive shaft.
Can bad CAT cause this evil exhaust smell?


Smell inside: With the window down in summer the exhaust smell reaches the inside. It is exceptionally bad at speed of 50mph and exhaust is probably drawn inside from the back through a leaking trunk lid gasket (open window creating a vacuum inside).
However also with the sun roof open the smell inside becomes really worse. Could it be that there might be a leaky exhaust manifolds and downpipe for instance?

Thank you for your help.

Martin

[lsmalley]

Originally Posted by werminghausen

it is by far the worst smell of all my Mercedes cars. And I don't understand why that is.

The exhaust system is in bad shape in general and I'll have to replace the downpipes soon. "They are very rusted out and might be leaking exhaust. Exhaust manifolds could be leaky at the heads."

Martin

If you have all of the above information, then why are you asking for help to resolve this without even trying to remedy the problems you've already clearly identified yourself?