Squealing Turbo

Checking bellows for cracks would be a good start, possibly turbo mounting gasket on its way out, or exhaust manifold leak, start with them and then check out both compressor wheels and make sure they haven't touched the housings!

 

Have you upgraded tour boot clamps? I cant keep the "stock" clamps tight enough to stay sealed above 40 psi. I just double clamped mine I can't find the ones with the 1" spring.(I haven't looked very hard either) I got rid of a lot of my original issues when I replaced the little blue hose and clamps that runs between the two turbos and operates the waste-gate/actuator. My BXS makes about 40-45 psi in the heat and 50-55 on crisp cool morning, I guessing your up around 60-65 with the BD. By the way I've been meaning to ask you does BD put enough timing back in it to cool the exhaust off any?

 

Yep, sounds like a pressure leak. Could be anywhere, but most likely turbo flange, exhaust manifold or air to air boot/clamp.

 

i had the same problem. thought it was a turbo. ended up being the serpentine belt slipping when fan was engaged. try it sitting still at high idle and turn fan on and off with manual switch to see if squeal goes away. dirt gets in the groves of the pulleys and lets it slip.

 

Check the turbos for shaft play. Disconnect the intake and grab the impeller and try to push it in and out and up and down. See if it wiggles in any way. The fins could be hitting the side of the turbo.

or it could be a intake gasket going out, clamp, boot or the cooler.

 

Had the same issue on a bxs. It was a stud on the exhaust manifold that broke. When in low boost it would "squeal" til the boost got higher.

 

If I had a squeal and suspected my fan belt or AC belt, then I would have cranked the truck and held a dry bar of soap against it, coating it from top and bottom a good bit, then went down the road to see if the sound went away. (My grandfather, a master mechanic, showed me this trick many years ago).

 

Should the soap be olay ? Or splash wintergreen?