I gave a rapping/clunking noise in my '79 300SD. It sounds like it is coming from the footwell area and sometimes I can feel it with my foot if I press against the inside of the firewall. It only does it when I hit some bumps in the road but sometimes I can feel a slight clunk when braking, but there is no instability of the car. It doesn't affect the handling of the car, but the noise is annoying. I am going on a 5000 mile trip next month and I would like to fix it before I leave.

I got under the car in a pit and used a wrecking bar to pry here and there (with car jacked up under frame)and I couldn't find anything loose or nor could I recreate the noise by prying under the wheels. It sounds like there is a bushing worn out or gone, but where are there any bushings in the firewall area? Or what else could it be?

P E H

P E H

taking a stab
 

Check your subframe mounts. I believe (not certain) the 116's have 2 on each side. Jack the car at the lifting points till the front wheels are off the ground. Look at the area where the front axle carrier mounts to the frame, if you see the rubber, your mounts are probably shot.

The crossover piece between the frame rails is the axle carrier. Make sure you aren't lifting the car from there, or you won't see the separation of torn mounts. The clunk you feel when braking is possibly the front axle shifting under the weight load and the thunk going over bumps is the axle bouncing.

Just a guess though.