Rumbling noise in back of 240D when making turns
 

It started three or four days ago... At first I thought it was something in the trunk rolling around during turns. What gives? Is it a differential problem, something loose I should worry about? Thanks for your opinions and advice.

Rino

Check the rear sway bar links. Common problem, easy and cheap fix.

Len

also check rear half shafts. the cv joints may be going.

tom w

its also a good idea to change the diff fluid to a good synthetic

Len, what should I look for and if it's that, what's the easy and cheap fix? Even if you just direct me to a website that explains it or other source, it would really be a great help and very much appreciated.

Tom, same thing here, what to look for, what to do about it. Where can I get an explanation of exactly what to check... what to do?

What do you guys use for that? Only God knows what's in it right now. I bought the car two years ago and the EZ Lube guys checked it only once (even though at each and every oil change they marked it on the service report as checked) and said "it was OK"...

Thank you all for your help,

Rino

One sway bar link on each rear wheel running vertically. They are about 6 to 8 inches long, plastic and bolted on top and bottom. Unbolt the old, bolt on the new and you're good to go. Cost ought to be under twenty bucks total.

Len

turning both ways, or only one? maybe bearings.check for play by jacking up and wiggleing the tires.

I run mobil 1 75-90? gear oil in my rear end.

half shafts- look to see that the boots aren't torn.

the half shafts should have no vertical play if grasped and wiggled up and down. you need to park the car with it in neutral and with the parking brake on so that there is no stress on the half shafts.

tom w

Turning both ways... but it seems to make a louder noise when turning right, though I am not 100% sure about this.

Thank you all for the precious advice!
I am ordering the Rhino ramps today and will check all that you suggested as soon as they get here...

Rino

I ended up building my own pair of ramps made of hard wood stacked and nailed together, 4" high... I am also getting the jackstands this weekend as I need to look into the brakes closely. So I'll do brake work first (hoping it will solve the rumbling/clunking/banging noise, then look into the other items you suggested.

UPDATE on locating more specifically the cause (it might help to better diagnose it):
I just noticed this morning that I got the same clunking/banging sound coming from the rear (several instances of it) while jacking up the front left wheel... does this pinpoint to a more specific problem? By the way, I don't drive the car at highway speeds... the clunking/rumbling noise happens when the car is driven slowly while making turns, or accessing the downward slope that leads to my garage.

Thanks...

Rino

I know it might seem simple but have you checked out the exhaust sytem support? Scoot under the back of the car and see if you can wiggle the exhaust system and replicate the sound...might just be a couple of stretched out suspension donuts barely holding up their end of the muffler. They are cheap and available at any parts shop and easy to replace.

still sounds like cv joints to me.

in jacking up the left front you also lift the left rear and depress the right rear. this changes the position of the cv joints and if they are bad they will rumble and clunk even without driving.

tom w

Thanks for the advice! I hope it is just that, I'll check it today... I'll try doing a more thorough inspection underneath, as suggested by others, this weekend... I've been postponing it, thinking of doing it after steam cleaning the bottom of my car, which is badly needed. "So much to do... and so little time..."

Rino

That's exactly what happened, then... I'll make time for a thorough inspection on Sunday and report back.

I also think the suspensions are gone... the car is very rigid and every bump I come across becomes a nightmare... I try to avoid every single bump that is on the road... I'll have to fix that too.

Rino