My last 300SD gave a turbo whistle upon accelerating, which I thought was normal. It was a fast car, too. My current 300SD was sluggish when I purchased it and I immediately noticed that I couldn't hear the turbo. This lead me to believe that the turbo was dead. After doing routine filter and fluid changes, adjusting valves, and backing the ALDA off completely I got a lot more power out of the vehicle.

I was still unhappy with the fact that I couldn't hear the turbo and I wanted to know if it was working. Today I removed the exhaust and drove the car. Wow, my turbo works for sure! I could hear it spool up and hear the waste gate open. I was turning heads and got a smile from a guy with a Ford Powerstroke. The engine was louder, but it wasn't annoying at all, it actually sounded good, like a big truck.

When I removed the exhaust I had to remove the flex pipe that goes between the turbo and the exhaust. There was a pipe inside of the flex pipe. Out of curiosity I did not put this pipe back in when I installed the flex pipe.

I drove the car again, and though the engine was back to being quiet as before I removed the exhaust, I could now hear the turbo with the exhaust attached! It's not as loud as without exhaust, but the engine is quiet and the turbo is audible over the engine when accelerating, just like my last 300SD. It sounds like a jet and I love it!

Now that I think of it, my last 300SD had no exhaust when I purchased it. Someone local gave me a used exhaust system but it did not have that pipe that fits inside the flex pipe. So, there you go. If you want to hear your turbo, remove the pipe inside the flex pipe.

I was tempted to make some holes in the flex pipe to allow more sound to come out, but I don't want the engine compartment filling up with smoke and soot. Though, I wonder if I could sleeve one so that it's open and allows the sound to escape while routing the exhaust down the pipe. In any case my exhaust is sealed.

I am considering having a custom exhaust downpipe made out of thinner metal that will transfer sound so that the turbo noise can come through it. I may remove the muffler while retaining the resonator if that will help make the turbo louder. The engine is loud enough for me; I just want turbo noise.

This was totally worth the hour spent removing the inner pipe. Imma firin' mah turbo! WOOO WOOO!

Below are some pictures of the pipe on a spare engine I have. I was tempted to use the damaged flex pipe in the last picture to get more sound out, but then I don't want the exhaust escaping, either.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles