I have an 82 300d turbo 123 chassis with about 300000 miles on it. This car is very noisy inside (engine noise) when i drive at high speeds, could anyone tell me if there is something i can look for that might be missing to quite this car down? P.S. I have checked the exhaust and there are no leaks or rust holes but this noise sound like it's coming from the back!

 

a sign of old age.

loose mountings, noise encapsulations, and muffler...?

 

Noise encapsulations. does that meen sound insulation in the floor? Also on the muffler there are 2 of them is the one in the middle of the car a resonator which do you suppose would be bad?

 

My 1959 180D was also extremely noisy, and for years I naturally assumed it was all engine noise. But during an interior renovation I drove it with the seats and carpeting out (I sat on a plastic milk-crate, if you must know) and found that most of the noise was coming from the back -- from the final drive/differential. specifically. I swapped in the rear axle from my parts car and the noise level went down by at least half. But that was the beginning of more problems -- see "rear axle/speedometer problems" thread for details before you try this!

 

I know it sounds crazy but I once took the carpet out of the trunk on my '82 300D Turbo and the cabin noice increased better than 50%.

In my opinion:
1. Make sure you have a good hood pad.
2. Make sure all the rubber mounts are good on the exhaust.
3. Make sure the spare tire is in the compartment in the trunk and the wood cover is over it. You can also put a thick rubber mat under the tire. The area where the tire fits is nothing more than a huge amplifier for noise so you have to deaden it.
4. Make sure the carpet is in the trunk over the spare tire area and over the fuel tank. Add extra carpet to help deaden the noise coming from the rear.
5. Use good quality quite tires. Cheapy tires seem to add to the road noise.
6. All bushings, mounts and shocks need to be in good shape.
7. Add insulation to the floor (under the carpet). JC Whitney has floor noise padding that works very well and is rather inexpensive.

These cars are a bit noisy by nature but they tend to get louder with age. The preceeding tips WILL help.

Good luck,
Tony T