I own two 126 300SDs (1981 and 1982). The 1981 has started making an exhaust noise that sounds somewhat like a Jacobson Exhaust Brake. It has a resonance around 1000 -1400 RPM. It sounds like it is coming from the area of the left rear portion of the center resonator.

I have inspected the entire exhaust system by removing it from the car. There are no holes or dents in any component. I have replaced the one seal in the system. I have replaced all the hangers. I even got a used exhaust system from Pull-a-Part which didn't change things much. The motor mounts are new Lemfoerder mounts and there is no metal to metal contact in that area.

My other car is only now starting to have the same problem, but to a much lesser degree. The 1981 has 276K miles and the 1982 has 291K miles.

My question is whether the center resonator is defective internally? Have many of you out there had to replace this componenet due to noise?

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Tom Evans
69 280SE 91K (wish I still had it)
73 220D 98K
78 300D 134K
78 300D 185K
81 300SD 301K (still have)
82 300SD 321K (still have)
84 300D 268K
84 6.2 Diesel GMC Suburban 225K (a whole different story!)

I replaced the entire exhaust system and had the shop run a straight pipe back to the rear muffler (Ansa).

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83 SD

84 CD

Internal baffles can break free and make noise. The typical USA design type muffler ( wrapped ) sometimes tears the external spot welds making the failure visible. I'm not sure about your car as the euro stuff uses a stamped muffler.

Pounding the exhaust with a rubber hammer might locate the problem.