'84 300D engine noise with load change
 

I hope someone can help me with diagnosing a strange engine noise in my 84 300D.

Here goes - cruising at 60MHP on a flat road the engine sound is normal, or at least what I expect normal to be. When encountering the slightest incline, such as an overpass, and not varying the accelerartor any at all, it's as if a switch had been turned on and instantaneously I get a loud engine noise. As soon as the load is decreased on the downhill side of the grade, the noise instantly goes away. I' mean - its just like someone turning a switch on and off! At first I thought it was a loose exh. manifold but then it would be doing it all the time. My attention focused on the exh. pipe and all of its connections to no avail - all seemed tight. I don't see any readily evident exh leaks anywhere. I haven't looked at the turbo charger yet but suspect it may be in there somewhere since that seems to be the last possible place to look.

Anyone have any experience with such a phenomenon or suspect what it could be?

Thanks

Can you describe the loud engine noise?

Are you using the Cruise control? If so, it is accelerating for you. Can you check and see if you getthe same noise when you accelerate?

Thanks for the reply but I guess I may have a toasted turbo on my hands. On the way to work this AM the noise (like an exhaust leak or wastegate open to atmosphere) got way worse, so bad that I had to return home and pick up my F250 to finish the commute. Parked the Benz in the driveway and will take a day off on Friday to tear it apart and analize.

I'm fairly certain its the turbo assembly and will confirm this weekend.

Any suggestions on where to get a quality rebuilt turbo for my '84 300D in short order - like overnight??