Bought my 05 new and now has 115k miles. Over the years sometimes it would do the hoot owl when the temps were below freezing and would stop within a couple of miles.

Now for the past few months the hoot owl is all the time no matter what the temp is outside. The noise goes up and down with rpm and in gear or neutral but not when it is sitting as I have listened in a rubber hose to try and find out where the noise is coming from.

I researched until my eyes hurt and find a ton of posts about the noise but not any fixes when the noise is under the hood, which I am quite sure it is. I have checked all the clamps, boots, hoses at turbo and intercooler but all seem fine. Truck runs fine and sometimes cranks a little longer to start cold but not excessive. I have new batteries and new cross over cable.

Any ideas? I have a 4k mile trip in 2 months and would like to get it fixed before I head out.

Thanks.

 

Hoot Owl? It may be the sound made by the fan. Normal on cold mornings and goes away after a short drive of a block or two. Never heard it on warmer mornings.
Back to morning brew.

 

Some call it turbo whine but I have never heard my turbo since I bought it. I don't think it is fan because now it does it below freezing and at 80°.

 

Does it make the noise constantly or at a particular rpm?

I had an 03 that eventually started to make a kazoo like buzz right at 2000 rpm.

Turns out there was an updated hose from the power steering pump to the brake hydrobooster that eliminates pedal/dash vibration.

The old style is a plain run, and the updated one has a metal coupler/restriction, and a big weight mid-span.

Just a guess, if your truck has the old style hose.

 

Goes up and down with rpm. I had it making the noise while my son listened all over under the hood with a hose and could not hear it. Standing beside the truck I can hear it or in the cab but not under the hood.

Stock I hit 30 boost so I assume my waste gate is ok?

New thing this week that I found while WOT checking the boost is the tranny does a quick up shift and the rpm goes into the red quickly then goes back down when it shifts. Split second for this to happen and I have always had the 1-2 upshift but this is new.

Can a transmission make a turbo sound?

 

Still trying to track this down as it is making the noise all the time now. Even took it to a diesel mechanic and he couldn't find it.

Took hose off turbo and bearing seems to be fine.

Loosened belt and turned every pulley, the one at the top in the middle turned fine but had a slight wabble.

Power steering pulley turned one way easy but couldn't turn it the other way by hand, is this normal?

Any ideas are welcome.

 

You got me. There was a TSB on stamped alternator bracket prone to crack. Newer part is solid/cast.

 

I never got that TSB but I will check it out.

 

Might have predated your truck, but my 03 had the issue.