sounds like.....
 

I had an interesting sound develope this weekend. It is most evident at 65mph when the engine is pulling, 3000 RPMs or so. It sounds like an air hose is leaking from the engine compartment. A high hissing sound. At low idle & stop & go driving the noise is not noticable. The only thing I can figure that would generate that kind of pressure under high RMP is the turbocharger. There is no loss of power or change in performance of the car. Any advice or ideas would by worth their weight in gold (or deisel fuel).


85 300d 232k

I think you're right in your assesment that its probably coming from the turbo related circuit. The '85 models had a different turbo set up compared to the earlier turbodiesels, so I can't offer any help on the subject. Could it be the EGR circuit? It operates at half throttle, so that might be another thing to check. Good luck.