high pitch squeal from under the hood.....turbo?
 

ok i have a question........the last 500 km i have been getting a high pitched squeal coming from the engine compartment it happens usually from around 20-30 psi boost and 2000-2200 rpms especially if the engine is not at full temp which usually runs at 188-194......it does make the noise at highway speeds but not as bad at lower speeds......it sorta sounds like a belt squeal or pully bearing squeal but it is not consistant.......the engine has 110,000 km on it.......anyone have any idea what this could be or has had similar problems?

check your idler pully for dry bearings.

On the 6.0's with a blown head gasket you could get a squeal as the combustion pressure entered the coolant system and exited through the coolant pressure capx(; usually under moderate to high boost. I would not consider it high frequency but a lower tone squeal...... similiar to low speed bushing, etc.......

Haven't heard of 6.4's having this problem but if you have also been losing coolant; or a tuner in the equation.......

Bob

no i havnt lost any coolant or anything like that........i guess i am gonna have to check my bearing on pully's and start that way first then move onto other things

Not an expert, but I second the idler pulley.

Your description sounds about like what I had happening. Turned out to be the idler pulley. I believe there's a TSB out there for the 6.4L concerning this problem. Sorry, don't know the number.

Not that it's cold outside yet (although it was in the 40's in Colorado Springs this morning on the way to the airport) but maybe this is the TSB?
https://www.ford-trucks.com/forums/8...ml#post7098031

That is the correct TSB.