strange acceleration noise on 300d ...part 2 - PeachParts Mercedes-Benz Forum

Dan62 · #1 03-25-2009, 07:52 PM

So I have isolated the strange acceleration noise on my 1984 300d, and I am pretty sure it is coming from the transmission. When I am in park it is a very faint hum like something is spinning softly, but when I put my vehicle into drive or reverse it changes slightly in pitch without moving. when I move in drive it increases in speed and pitch and then comes down in speed and pitch with each shift. What could this be? Also, I first noticed this sound after accidentally driving over a curbed parking spot divider in a dimly lit parking lot. I heard the bottom of the car knock the curb.

If anyone has any idea of what this might be it would be greatly appreciated.
Dan

pawoSD · #2 03-25-2009, 08:28 PM

So you drove over a curb, which hit the bottom of the car, and did not thoroughly inspect it under there for damage right away??? Sigh. (I'd have stopped immediately and done a once-over to make sure it was ok)

Anyways, I'd be putting it up and checking everything....you could have dented a pan on the engine or transmission, or damaged a mount, or any list of things....the engine/trans/torque converter housing all hang pretty low and could have been hit.

777funk · #3 03-25-2009, 09:30 PM

Quote:

Originally Posted by pawoSD

So you drove over a curb, which hit the bottom of the car, and did not thoroughly inspect it under there for damage right away??? Sigh. (I'd have stopped immediately and done a once-over to make sure it was ok)

Anyways, I'd be putting it up and checking everything....you could have dented a pan on the engine or transmission, or damaged a mount, or any list of things....the engine/trans/torque converter housing all hang pretty low and could have been hit.

Hey give Dan a break! This is his 1st MB.

But yeah I'd take a good look under there Dan. I'd also check to make sure your oil and transmission fluid are at the right levels. Last thing you want is something draining before a long drive or really any drive for that matter.

Let me know what you find Dan.
Nick

WhoWhat · #4 03-25-2009, 09:37 PM

Quote:

Originally Posted by pawoSD

Anyways, I'd be putting it up and checking everything....you could have dented a pan on the engine or transmission, or damaged a mount, or any list of things....the engine/trans/torque converter housing all hang pretty low and could have been hit.

x2. Give everything a once over underneath. Even if you're not sure what something is, you'll at least be able to tell if something's been scraped along a curb.

Could your noise be a loose/noisy belt from the engine compartment? Sometimes, the noise pitch of the moving parts changes when engaging the transmission. It seems that if the noise raises and lowers with speed and/or engine RPMs, it has to be a moving part of some kind.

Dan62 · #5 03-25-2009, 09:55 PM

I have looked under the car several times and did not notice any damage, scrapes or dents to the transmission. I have also checked the engine and did not hear any sounds coming from any of the parts that the belts are connected to. both the engine oil and the transmission fluid are ok, but the transmission fluid is just above the add mark. I will check it all over again before work in the morning to see where the levels are.

pawoSD · #6 03-25-2009, 11:25 PM

I'd put it on ramps or a lift and get a better look at everything, especially if a new noise came about after the impact....