Cabin noise reduction & new muffler???
 

Maybe I’m just being more sensitive to the noise lately – or maybe mufflers wear out internally?

I am wondering if anyone has had a noticeable drop in interior cabin noise at freeway speeds when they have replaced the center resonator and the rear muffler? If so, could you please say how much of a difference there was, and what was the condition of the exhaust system that you replaced?

My car’s exhaust system is original (1984 300D, 220,000 miles) and there are not any large holes or anything, but it looks like corrosion is just starting to surface. I am wondering if the internal baffles start to rot out & cause a progressive increase in noise, especially when the engine is under load. There is a LARGE difference in noise levels when traveling 70mph and coasting versus cruising. The noise is not just the injection pump and injectors – it is a pretty significant roaring.

Any input would be greatly appreciated.

The center resonator on my W123 rusted on the top so it was leaking and slightly louder. It took me a while to realize it because I couldn't see any rust but eventually I started getting fumes drawn into the passenger compartment so it was obvious I had a hole somewhere. Take a look the next time you are under your car to see if there is any soot buildup around the mufflers. If so you may have a leak on top that you can't see. My new exhaust did make my car a bit quieter but not by a whole lot.

Noise,


Noise on W123's is been a hot issue for a long time. First, these cars WERE not loud new. Only anoiance at highway speeds suggest deterioration in weatherstripping, firewall seals, and engine insulation.

My car, there was a very small tear in the floor board and it made the drivers side hugely noisy- drop of sealant and it's quiter. Every hole in the firewall has a seal. AC lines, gas pedal, speedometer cable, wiring, oil pressure line. If you start digging around, I bet some or all of these have deteriorated. You can replace them or some people use some silicone to seal them.


You can email me directly, I've done some of this to several cars.

Michael

RunningTooHot,

On my 1982 240D my daughter started complaining about the car getting louder and I began looking it over. The exhaust system was a little used here and there so we put a new pipe in from the manifold to the resonator, and a new resonator. Helped but did not completely solve the problem. Then I found the flexible connection between the intake and exhaust controlled by the EGR valve had a big hole in it. Changed that (very sharp edges!) and it got a little better. So I left it alone for a while and she continued to complain. Then I found the exhaust manifold was loose. New gasket for intake and exhaust and new fasteners, and the problem was conquered. It is still not a quiet car, but I think it is back to its original annoying noise level instead of objectionable level. At least my daughter's response changed, so I count that as a success. Good luck, Jim