Thread: 300Tdi - turbo issue?

My 300Tdi has been running brilliantly recently with a new timing belt and a boost pin but all of a sudden it started making a screaming noise. It started intermittently for a few seconds and then continuously and loud. I was driving at 70kph down hill at the time. I pulled over and let it idle and the noise went away.

My first though was belts and maybe a dodgy tensioner. Changed the tensioner and was ok.

Then driving uphill at 80 it returns, so pull over let it get back to idle and disappears again. The most recent incident driving on the flat at 80 and it starts screaming, so I thought I will just put it in neutral and let the revs drop while still moving (no other traffic around) but the noise didn’t go away. I pulled off and came to a standstill and it did go away then drove off as before with no issues.

What might be causing this?

I had a similar issue some years back. It turned out to be a rubber elbow in the line between the turbo and the intercooler. It was delaminating internally, which caused a screaming/whistling noise, and loss of power due to restricted air supply to the engine. The restriction wouldn't be an issue at idle or coast, but under load you'd notice it. I've also experienced an alternator seize-up, such that it stalled the engine at low rev's and the only way to restart was roll-start with clouds of smoke coming off the accessory drive belt at the crank pulley. Shut down immediately as the water pump wasn't turning.
Look for a simple solution before imagining the worst!
Cheers, Rob S