Turbo Question

[Gary Burris]

I have a 2007 6.0 Diesel. After the truck sits overnight, when I start the engine and start down the road there is a whistle, when the boost pressure rises from 0 to 10 psi but then the sound disappears. When the engine is warm the whistle is not there no matter what the boost pressure is. Is this normal or do I have a head gasket leaking?

[PGreenSVT]

I suppose it depends on where the whistle is coming from. The turbo will normally whistle some from the tail pipe. It tends to be more noticeable at lower rpm and boost levels.

Head gaskets tend to leak worse as the engine warms up and you get heat expansion. Blown head gaskets typically do not cause a whistle. Could the whistle be coming from your degass tank cap? That could happen if the cap is bad. It could also happen if a bad head gasket is over pressurizing the cooling system. In this case you get a tea kettle kind of whistle and puking from the degass tank. This usually happens when warm and under a load though.

Is your truck puking or losing coolant? Do a little digging around in the engine compartment and let us know what you find.

[Gary Burris]

I am not loosing coolant or puking coolant. I will check the degass cap

Thank you

[Face Down]

You most likely have a crack in one of the three flexible joints in your up-pipe. I had the same thing...at idle I would get a intermittent "dog whistle" that would go away when I hit the skinny pedal...only to return again while sitting at a light or in a drive-thru. I just did a full EGR delete and got lucky as the crack was in the EGR portion of the up-pipe that I replaced. Unfortunately it is hard to tell where it is coming from until you tear everything apart. If you get lucky you can crawl under the truck and look for some soot on the firewall to pin point which joint it is coming from...I tried that and could see squat!

[Gary Burris]

Thank you for the information

[PGreenSVT]

Good observation Face Down. If it is a leaking bellows in the up pipe or Y pipe one way to get an idea where it is coming from is to open the hood and power brake the truck for a few seconds. you should get a telltale of soot from the area that's leaking.