My car: 1985 300D (Calif.)
Mileage: 219,000
Problem: A strong exhaust smell that I suspect is the product of a leak.

Background:
6 years - 15,000 miles ago, I replaced the center + rear mufflers due to deterioration from rust. At the same time, I also replaced the down/front exhaust pipe that is situated between the exhaust connection near the battery and the center muffler pipe due to that piece simply falling apart. All was well.

About 2 years ago, I began to notice the strong smell of exhaust when I would exit the driver’s side while the engine was running or just get out of the car after shutting the engine off. I’ve driven and maintained two W123.153 vehicles for around 30 years and I’m certain that there is an exhaust leak because excluding the last 2 years or so, I’ve never encountered this strong of an exhaust smell. And incidentally, there is no visible smoking and mileage remains as it has been for decades.

I have carefully and repeatedly inspected each joint of the exhaust system and found no signs of leakage in the form of soot. I’ve also used exhaust system putty on the joint between the center and rear muffler and the smell continues.

Given the above, I have been wondering:
For a car of this age (going on 37 years, 219,000 miles), is it possible/likely that the intake-exhaust manifold gasket has failed and is thus leaking the exhaust?
Since that area of the engine is black from the factory, dirty in general, and difficult to access, I’ve been unable to visually detect a soot leak in the area if one exists.
On the other hand, I have removed the turbo charger on several of these vehicles and done a head replacement and know the amount of work that is required and so, I’d prefer not to disconnect the exhaust and remove the turbo if a manifold gasket failure is underheard of or extremely unlikely.

My questions:
1. Is there anywhere else that I should be checking for an exhaust leak?
2. Does anyone have experience with the intake-exhaust manifold gasket failing at this sort of mileage or age?

I’d appreciate any help with this. Thanks-

I would look for a small exhaust leak by feeling around all the joints with the motor running. Especially around the flex pipe section.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Ok. That should be a fairly quick undertaking considering that there are only 4 or 5 if I recall accurately. Thank you.

Another way is find a shop that has a smoke machine used to find vacuum leaks. Have them fill the tailpipe with smoke, you should be able to pinpoint any leaking areas.....

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Another excellent idea I hadn't thought of. Great. Thanks-

Have a helper plug the tailpipe with an old towel. If there's a leak it'll be pretty easy to find.....

The best way to find an exhaust leak that's not obvious is a mechanics stethoscope. They're cheap to buy. Great to locate engine noises with the metal probe or remove the diaphragm/probe and use the open plastic tube end for exhaust leaks. https://www.google.com/search?q=lisle+52500+mechanic%27s+stethoscope&rlz=1C1RXQR_enUS967US967&oq=52500+mech&aqs=chrome.1.69i57j0i22i30j69i60l2.9507j1j7&sourceid=chrome&ie=UTF-8

Actually, I have a mechanic's stethoscope. Hadn't considered using it the way you describe. Interesting. Thanks-

Yeah, this would probably make quick work of finding a leak(s). Thank you.