1983 300D Turbo, 143,xxx miles:

I have an odd, loud problem coming from the instrument panel. Sometimes when driving, around 60 mph, out of nowhere a very loud wailing and "vibrating buzz" type noise comes from my dash, drivers side, sounds like it's coming out of somewhere between the speaker and the instrument panel. Every time it has happened, I've had the defrost on as well as the radio. When it first happened, I shut off the heat (no difference), then the radio (also no difference). The only thing that makes it stop is if i slow down to less than 30 mph and then resume normal highway speed. It seems to only happen once per drive, i.e., it doesn't come back when I get back up to 60 mph. There is no gradual build but there is a gradual decline as I slow down. Decline in volume and intensity. But when it first starts, it's immediate, without warning, and very loud. This has caused a couple mini heart attacks as well as pretty dangerous "jumps" of fright on my part. Worried with the winter coming and snow piling up, I'm going to scare myself and jerk the wheel or something ridiculous and end up in the ditch. Also, this typically occurs in the early morning on my way to work, in the cold. I start my car and give it time to warm up in the garage before I drive it but outside it's still cold in upstate New York. Any ideas, or is this just a ghost infested Benz?

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1985 300D - 1984 Euro 280E AMG Clone (SOLD) - 1978 280CE (SOLD) - 1983 300D (SOLD) - 1981 300D (SOLD)

I vote for the speedometer drive cable though, the relationship to the defrost and radio are perplexing. Try driving without both and see if it makes a difference.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250

Ooh ooh... I know this one.

I had a similar noise in my wagon. What it was for me, was the door lock check valve that is under the dash. It's up behind the cluster and near the speaker, right up next to the windshield. Try blocking off the vacuum to the door lock system, and see if that makes the noise stop. If it does then you've got a leak in your door lock system to find. If it doesn't then I'm all wrong.

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Who ya gonna call..................
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BENZ BUSTERS

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

Ha! Alright, all joking aside...

I'm going to check out both of these responses, however, I need a little more info to continue on. First of all, are there any pictorials on doing either of these jobs? Maybe I should look first before I ask.... Second, how does one block off the vacuum to the door lock system? Does it help to know that my locks are extremely slow to lock and unlock? Do I block this off and then drive to work hoping that it happens again? Can I lube the speedometer drive cable or do I need to flat out replace it?

And finally, a new question (which should probably be it's own thread, one that I might start if I don't get any responses): If I'm going to open up the dash to do any of these things, what jobs should I just tack on since I'm opening it up anyway? Are there little things or big things that might need fixin' in my old Benz? Thanks for all the help!

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1985 300D - 1984 Euro 280E AMG Clone (SOLD) - 1978 280CE (SOLD) - 1983 300D (SOLD) - 1981 300D (SOLD)

Sounds like the spedo cable to me too. Mine used to do that when it was cold. A shot of 3-in-1 oil did the trick.

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1979 240D- 316K miles - VGT Turbo, Intercooler, Stick Shift, Many Other Mods - Daily Driver

1982 300SD - 232K miles - Wife's Daily Driver

1986 560SL - Wife's red speed machine

My 1979 300SD does it, too! When it first happened I though that the transmission had gone bad and my engine was over-revving. It does it mostly in the morning when it's cold. It screams on the freeway and is really loud. My odometer is not working and I think maybe it is the odometer gears grinding on each other.

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Stop paying for animal enslavement, cruelty, and slaughter. Save your health and the planet. Go vegan! I did 18 years ago. https://challenge22.com/

DON'T MESS WITH MY MERCEDES!


1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

To lube up the speedo cable, you'll have to pull the instrument cluster out. Either with hooks on the sides or push it out from the back. Then put a little lube into the cable.

To block off the door lock system, you can put a golf T in the supply line that supplies the system with vac in the engine bay. The door lock system has yellow vac lines. Look in your engine bay near the brake booster. You will find a solid yellow line and a yellow line with a brown strip. Both of these are connected to a 3-way rubber connector. Block off the line that supplies that 3-way with vac. Here is a photo of mine.

You might also try blocking off the climate control vac. It's the green line with the yellow stripe. You can see it in the pic too. Do them one at a time so you can tell which system is the culprit if one is.

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Mine used to do that and then just stopped doing it one day.

Maybe it was the Holy Water I sprinkled on the dash...

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'79 300SD
'82 Chevy Chevette diesel

My 1991 350SD had a similar noise problem. When cold out, starting at about 25mph a loud noise started. Sounded like it was from the dash area, then right side, also rear.
It turned out to be a bad driveshaft support bearing. My car required two.
Had them replaced & no noise for the past 6 months.

Speedo Cable. Mine was doing this and some lubricant fixed it!