1995 Turbo 6.5

[Doug Thom]

My 1995 Silverado 6.5 Turbo has developed a problem that I could use some help on please. It has 290000 Km's and yesterday as I accelerate I'm hearing a whistling sound. When I take my foot off the accelerator, no noise. I "suspect" it may be the turbo (original). My question is: is there a fix for these turbos or are they simply a replacement? I have a friend (mechanic) going to have look at the truck this morning.
Thanks for any help you can offer!
Doug

[simon]

if you never heard the turbo wistle before,i would suspect an airleak post turbo,intake gasket,plenum bolts loose , hole in turbo to snorkel hose,etc.
check belt tensioner pulley for bad bearing.

[DmaxMaverick]

It sounds like you may have an intake pressure leak. Check the connection between the turbo compressor and intake, the intake plenum cover, and manifold to head. Any of these can "whistle" if they leak. The rubber coupling between the turbo compressor and intake cover are a common leak location. If the clamp loosens or the hose is damaged, it will leak. In most cases, evidence of oil spray will be present in the area of a leak (from the crankcase vent oil vapor). An exhaust leak can also whistle, if it's somewhere between the head and turbine housing. A failed/failing turbo won't normally "whistle" (because of a failure), although it can during normal operation.