I have been reading the archives regarding turbo "whine" as my 1985 300D has similar problems.

The turbo was rebuilt by Majestic Turbo in Texas. Since re-installation, I have noticed a "whine" as the turbo spools up, then quiets down somewhat at highway speeds, although noticable.

It does not sound like a whistle or air leak. The sound is more like a turbine engine spooling up, almost like a siren. The archives suggest there is a possibility of the flex pipe behind the turbo being the problem.


I did not drop the exhaust assembly when I removed the turbo, rather I removed the three flange bolts, moved downpipe around enough to remove the flexpipe, then removed the turbo. Also, I did not remove the intake or exhaust manifold. When re-installing the flex pipe, I noticed it was just a little off angle between the turbo and downpipe. I would think if anything, there would be an loud exhaust leak, unless the sleeve inside the flex pipe is lined up properly and the turbo is "leaking air" around the flex pipe. Any thoughts? Alan