w2hmh

I have a 1991 350SD with 185,000 miles. It is very clean and runs very well, only uses a bit over 1qt oil between changes (5,000mi). When I bought this car about 20,000 miles ago I replaced the rear muffler and pipe with new MB parts. Although the front muffler (is that the right term?) only had evidence of a few very small leaks I wanted to replace it, but have been unable to find one anywhere. I patched(welded) the few small holes and carried on. I don't believe there are any leaks, but the car seems somewhat loud ( hasn't changed since I bought it). This may be simply that I am unfamiliar with what these cars should sound like, but the exhaust exhibits a "raspy/buzzing/vibrating" exhaust sound at around 2,000 rpm that seems to be coming from the front muffler (has been this way since I bought it).

Has anyone experienced anything like this?
Does anyone have any experience with noise reduction with these cars?
What is the function of the front muffler and how does it affect noise levels?
Has anyone ever replaced the front muffler with an aftermarket one with any success?...if so what product did you use?
Has anyone ever replaced the front muffler with a pipe?....how did this affect the noise level?

Apologies for all the questions here, but any experience or thoughts on this would be much appreciated.

Henry

MPH 350SDL

Based on my experience with a 350SDL that I bought used and have put 145K miles on, your description of the exhaust noise is normal. You will hear a buzz/rattle noise at 2000 RPM. I can't tell you why, but they just make that noise. It's nothing to be concerned with.

w2hmh

Thanks for the feedback...much appreciated

yeahrightnc

My '91 (114K miles) does this exact same thing. Would Mercedes really have put an S-Class on the road at this point in time, with a design flaw like that? I have ridden in other 350SDLs that didn't seem to make this noise - it's like a buzzing/rattling noise from the left rear of the car. I checked the heat shield (and even put asphalt sound-deadening material on it), but it still rattles like crazy when it's cold. Lessens somewhat as the car warms up, and not nearly as noticeable in the summer. Beautiful car - runs great, burns no oil, no signs of bent rods as yet (hoping I got a good one). It turns heads - and I have people stop and look at it all the time. But that vibration is right at 45mph - and living in the city, I'm in that speed range all the time. 65mph on the road and it's quiet as a church. Keep hoping I can find a fix - going to have my mechanic look at it and see if he can figure it out.

yeahrightnc

Mine's gotten REALLY bad - weather's getting colder and this exhaust is really starting to make noise. It used to go away for the most part once the car warmed up, but it seems to be noticeable all the time now. Really bad first starting out in the mornings; takes a few miles for it to not sound really obnoxious. I hope it can't be heard outside the car.....