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#1
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Exhaust
My 84 300 SD is making a strange noise.
I removed the crossover resonator and replaced it with a straight piece of exhaust tubing. My noise started at about the same time. I can't put the resonator back on but I don't know what else might be causing the noise . The car doesn't have to be moving and the noise will come on at about 1000 rpm and go away by about 1500. Can anyone tell me what the resonator is supposed to be doing. I can't believe MB put it there for no reason and it must cost a ton. The exhaust is not loud so it doesn't seem noise was the reason. Thanks,
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Darrell 1984 300SD "Ole Girl" 207K |
#2
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What kind of strange noise?
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar. 83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles 08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles 88 Jaguar XJS V12 94,xxx miles. Work in progress. |
#3
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Quote:
It has never been unusual for exhaust 'mods' on the turbodiesels to result in resonance or vibration in the cabin at certain rpms. The original equipment exhaust is designed a certain way for a reason. Did you weld the new, replacement piece in or did you clamp it? No the OEM setup does not cost a 'ton', but that depends on what your definition of a ton may be....
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Mac 2002 e320 4matic estate│1985 300d│1980 300td Previous: 1979 & 1982 & 1983 300sd │ 1982 240d “Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22 |
#4
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The noise is somewhat like a rhythmic knocking noise but it is not a metallic, solid sounding noise.
It happens at low engine speed and seems to increase in frequency then disappear with higher engine speed. It is most easy to hear from inside the cabin. It can be heard moving or stopped. The resonator is the dual crossover resonator which I replaced with a straight piece of tubing welded in place. I have heard most common engine noises, rod, main bearing, piston etc. and this does not sound like any of those I have ever heard.
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Darrell 1984 300SD "Ole Girl" 207K |
#5
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Quote:
As for the noise - have a look at the underside of the car with some trustworthy person revving the engine for you.
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1992 W201 190E 1.8 171,000 km - Daily driver 1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone 1965 Land Rover Series 2a Station Wagon CIS recovery therapy! 1961 Volvo PV544 Bare metal rat rod-ish thing I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior Don't leave that there - I'll take it to bits! |
#6
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Quote:
Anyway, the noise that resulted was similar to what you are describing. Your support may be missing or damaged and the exhaust work you did is just amplifying the problem.
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Mac 2002 e320 4matic estate│1985 300d│1980 300td Previous: 1979 & 1982 & 1983 300sd │ 1982 240d “Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22 |
#7
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It's most likely a resonance from the engine. When my exhaust finally fell off, I had the nastiest drone that drove me nuts. I sounded like a boat with the farting exhaust.
The exhaust shop I took my car to laughed when I said I took off the exhaust myself. I ended up having the last laugh when they saw that I did correctly removed the exhaust myself.
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-Typos courtesy of my mobile phone. |
#8
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Rhythmic knocking: Very likely the exhaust moving around and making contact with something else under the car. Check your hangers and mounts.
I had a similar sound come from my 300D approximately halfway between my origin (Nevada) and destination (Georgia) on a cross country trip. I was a bit worried until I looked and realized I just needed some new muffler hangers.
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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar. 83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles 08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles 88 Jaguar XJS V12 94,xxx miles. Work in progress. |
#9
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Not sure if your year has this, but just down from the exhaust manifold is a 8" long secton of braided steel with flexible pipe under it. This area is prone to cracking and an exhaust leak. Mine is leaking now and hear the noise from both in and outside of the car.
Let us know once you find out
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1987 300TD 147,000 miles- Palomino leather interior, 1995 facelift and body cladding, E350 wheels, Rebuilt suspension and sport springs, rebuilt turbo, New Monarch injection pump and injectors....and the list goes on and on... |
#10
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Well I've checked everything I can find or think of with no luck.
The exhaust downpipe was replaced prior to all this happening. The support for that bolts up to the front of the transmission housing with rubber grommets and it all looks good. I guess when whatever is causing it gets bad enough I will find it. I don't know what else to check at this point. I am either looking for the wrong thing or missing whatever is causing this. Thanks for all the suggestions.
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Darrell 1984 300SD "Ole Girl" 207K |
#11
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This is going to sound cray, but I am wondering if it is coming from the fuel return line going to the tank. Does it have the cigar hose or has someone replaced the return line with a piece of regular fuel hose? It will resonate like hell and gives the characteristics you describe. Mine did it and drove me nuts until I replaced it.
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Thanks, Mark in NC "Spark plugs?...We don't need no stinking spark plugs!" 1985 300SD "Der Silberne Schlitten" 420,000 mi Wish these were diesel: 2003 Ford Club Wagon 130,000 mi |
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