300CE 24 - Gearbox noise paranoia

[Ade W124]

Done a quick search but nothing seemed to match my latest query...It could be nothing (first MB and first auto) but I've noticed a new noise in the car in the last few times I've used it.

When the car is held stationary in R or D, there is a quiet but distinct grumble from the front/middle of the car. Its not there in neutral and once the car is moving although it is there when creeping in traffic at tickover (typical London driving... ). It seems worse when the car is hot.

Now obviously when in D the something is spinning in the gearbox which is not when in N and I would expect a noise change and drop in revs, however this one doesn't sound right to my ears... its as if there is a ropy bearing in something which once loaded up realigns itself..

Checked the ATF, the level is good and its clear (recently given the thumbs up by Automerc) and the changes are smooth and quiet when running at any speed other than the aforementioned crawl and stop.

Am I getting worked up about nothing or is something about to fall off? Car is from 1991 on 52k and has done 2k since indy inspection before I bought it which gave it a relatively clean bill of health.

Ade

 

[Hibbo]

Strange as it may sound I don't think this is a gearbox noise at all. My first guess would be knackered engine and/or gearbox mounts.

This may also sound strange, but when stationary in N, something in the gearbox IS spinning, then when you select D or R, the WHOLE GEARBOX IS STILL.
This is because when you're in D or R, the gearbox is locked to the stationary wheels, the torque converter slips and effectively disconnects the engine from the gearbox.

When you engage D or R torque is transmitted through the propshaft and this causes the engine and box to twist slightly on their mounts. If your mounts are on the way out this can transmit engine vibrations into the car.

Sit in the car with it in N (or P ) and with the engine running get someone to compress each engine mount with a pry bar. If this recreates the problem then there's your cure!

 

[television]

I looked at the post earlier, but my mind went blank, thanks to Hibbo it came back to life and it is worth checking the engine mounts.

Malcolm

 

[Ade W124]

Funny, engine mounts were the first thing I thought of.... and then I thought na...

My guess is its not an urgent fix, will postpone further investigation until I have finished moving house..

Thanks for the tips

Ade

 

[television]

Funny, engine mounts were the first thing I thought of.... and then I thought na...

will postpone further investigation until I have finished moving house..

Thanks for the tips

Ade

How far are you going to move it


Malcolm

 

[Ade W124]

About 15 miles... NE to SE London

Ade