1979 300d NA 290k

This morning (first frost) I head out and about a mile down the highway
a loud whine starts, after I turn off the radio it almost sound like a bad
fan motor or similar but it is speed dependent.

It’s loud inside the car , the speedo needle is smooth, heater motor is off.

As I slow to the signal light it gets less noisy and it’s gone at stop. As I
accelerate away from the light on the first shift, the noise starts again.

I take it slow and easy as I’m almost at my destination.

As I slow for the turn and accelerate again, no noise. 1/8th of a mile later
I stop.

At first break I’m going to start it up and check the fluid level in the tranny
just in case but any other ideas as to what it could be.

I drove the car last night along the same route and the same speeds
and much further without issue.

To be honest it has sat for about a month since I last drove it.

Not sure what thread title has to do with the issue…

Anyway, if the car has not moved in a while, rust in the parking brake can be noisy for a few miles.

Check your fan, and belts… alternator, power steering fluid etc.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

https://www.youtube.com/watch?v=F1ZhD6T0yVw

Speedometer cable lubrication-76 300D

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“Whatever story you're telling, it will be more interesting if, at the end you add, "and then everything burst into flames.”
― Brian P. Cleary, You Oughta Know By Now

I had this problem in a '79 300D and it turned out to be water in the speedo cable had turned to ice. I pulled the cable out of the car, hit it with a hair dryer to get it really warm, let it sit for a bit in the hope that the water was gone, then lubed it. Noise went away.

Phil Forrest

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1972 220D "Trudy," named by a friend.

"The 220D sounds good... I suspect it is the only car that you need a calendar for, rather than a stopwatch, when doing acceleration tests."
Tom Abrahamsson

The 450SEL would do the same thing when it got cold. Sudden loud noise as speed increased, not going away until speed was near zero. Speedo needle didn’t look like it was affected at first glance but if you watched it, you could see something was up. A bit of flutter that wasn’t normal if I remember right.

The inner core of the cable can start oscillating in the housing due to lack of lubrication. No amount of cussing or banging on the dash will fix it, it must be properly lubricated.

Michael

That's the noise...

Hard to believe a cable can make that much noise without the speedo
needle jumping all over the place.

Thanks!

Not only does it make that much noise, it can do it randomly and without warning which can startle a person real good.

Michael