straight pipe project - PeachParts Mercedes-Benz Forum

ivandrocco · #1 11-08-2011, 11:58 AM

my 84 coupe has a weird exhaust issue where the bend just before the muffler whacks against the trailing arm after driving on the highway. You can see where it's hitting because the pipe is at least half crushed in at that spot.

I think this is a coupe specific exhaust routing problem- not sure why my exhaust is shaking so much... i've eliminated most of the engine shake and replaced the hangers.

I'm just going to solve the problem by straight piping the exhaust and routing it away from the training arm.

I was planning on removing the muffler but keeping the resonator so it's not too loud, but after looking at this, it seems like it makes more sense to delete the resonator and keep the muffler because the resonator section has more bends.... Straight pipe exhaust

What do you all recommend?

here's my original thread with photos: exhaust pipe clunking trailing arm

vstech · #2 11-08-2011, 12:13 PM

I'd think the muffler hangers need replacement. a lift to see where everything is touching at once would be helpful!

pwjeep · #3 11-08-2011, 12:15 PM

This sounds like a paraphrase of Shakespere's "To be or not to be..."

My exhaust system on my 240D 4 speed manual was rotted after the down pipe. I went a local muffler shop and said I'll have a straight pipe please. After a little consternation by the proprieter who said "We don't install straight pipes" I immediately settled him down with... "It's a diesel!" He immediately agreed because there was no catalytic converter involved. The vehicle seemed to have much more pick up and for a 240D it seemed almost zippy. The down side is that it was very loud. They custom bent the pipe and it worked great. Several months later I went back as I could barely hear the radio when I accelerated. I was concerned enough about the noise and getting a ticket for it that I had a muffler installed at the rear. I suppose you would get the same kind of noise with a NA 300D

One of my friends has a 300D with a turbo without the muffler. It does not sound loud at all. He says it's because the turbo modulates the exhaust sound. So you could probably get by without a muffler on this kind of car with a turbo.

It's a lot less expensive without the muffler. Ask for a quote first.

ivandrocco · #4 11-08-2011, 12:21 PM

vstech, replaced hangers, used the expensive reinforced ones too. I said that in my first post.

pwjeep, i've been reading about this. I know i can get away without the muffler or the resonator and just a straight pipe. Keeping one apparently makes the noise more manageable. I want to know which one I should keep!

vstech · #5 11-08-2011, 12:31 PM

I saw where you mentioned they had been replaced, but it really looks like I could figure out better what to adjust if you took a pic from the underside of the car.
it could be as simple as loosening the flange, and rotating the pipe a tad one way or the other.

If you are determined to straight pipe, I'd keep the resonator.
the turbo's are quieter than the N/A's but still rumbely without the resonator.

ColLonewolf · #6 11-08-2011, 03:46 PM

Mine has been straight piped for years. Just remove all that unneeded weight. The turbo is a muffler as far as the gov is concerned and it is really not that loud.

pwjeep · #7 11-09-2011, 10:05 AM

Muffler or resonator??? I'd get the one that is the least expensive. I don't know which one would produce the most / least noise. At this point in time, there should be a web page that should be able to tell you the db reduction for a typical muffler / resonator. One should be enough. I think MB does a little bit of overkill on noise reduction. But, I'm hearing challenged.

ivandrocco · #8 11-09-2011, 03:05 PM

chopped it all up and just put the resonator in the space the muffler was in before. clamped it all together and im going to weld a tailpipe and hangers to the resonator. Sounds awesome, wasn't even too loud running around town with nothing bolted on.

mach0415 · #9 11-09-2011, 05:26 PM

I have had mine straight piped the whole way from the turbo to the rear bumper. No complaints. I do a lot of highway miles (45 minutes commute to work everyday and 45 minutes back) and am not annoyed by any droning over that time. I am also prolly deafer than most, as I have worked around machinery my whole life

. Received a lot of compliments, though.

ivandrocco · #10 11-09-2011, 07:41 PM

yeah mine sounded a little gurgley without anything. The resonator gives it a nice growl.

feels much more responsive too now. i highly recommend this mod.

it cost me abut 25 bucks total, and i didn't really need to braze the tailpipe to the resonator. Could do the whole job with a hacksaw and a few clamps.

Dieselboy740 · #11 11-11-2011, 02:10 AM

Mine is 3.5" straight piped. Sounds a little funny on the bottom end but smooths out foa decent 5cyl purr around 2500-3000.

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