Engine/Transmission (1998.5 - 2002) Whistling sound

[JDoiron]

I have developed a whistling sound from under the hood of my 2002 Dodge 3/4 ton diesel. I have tried to find it but cannot hear it with the hood open. I have had someone rev the engine and I still cannot hear it. It only whistling while driving and accelerating. If you shift into neutral while driving down the road and rev the engine you cannot hear anything. It only happens when you put it back in drive and continue driving. The Whistle gets louder as RPM's go up. All gages and fuel mileage normal. It almost sounds like an air leak sound. Hi pitch and up with the revs. Any suggestions?

 

[promisedland]

Ummm, you hearing the turbo?
Sorry, somebody had to say this!

 

[JDoiron]

I was afraid of that. What are my options? Should I park it? I cant hear any whistling while cruising down the road, just getting up to speed. Is this an expensive fix?

 

[BigPapa]

Don't mind him, he's just joking. He's got a new turbo and air filter that lets him hear more turbo whine. His ears are still ringing. :-laf

I guarantee you it's a boost leak. Your only hearing it under boost. The system doesn't build enough boost for a long enough time unless the engine is under load. You need to get you a spray bottle with water and 3-4 drops of dish washing liquid and pressurize the system. Spray the water/soap on every joint and boot and don't forget the intake horn and intake plate where it bolts to the head. Had a buddy who's intake plate gasket had broken and caused a whistle.

Here is a link to a good thread about pressurizing the system:

https://www.turbodieselregister.com/threads/185133-How-to-pressure-test-intake-system

 

[JDoiron]

Wow I think I can do that. What do you mean pressurize the system? Where and how. The noise is not a metal to metal sound but more like a whistle and does sound Turbo related by the way the sound goes up and down with throttle.

 

[BigPapa]

What do you mean pressurize the system? Where and how.

Click on the link to the other thread and read it. Tells you all about it with several options on the "how". Take your pick.

 

[Bob4x4]

You can do a visual inspection first,On the 2nd gen trucks the inner fender liners are metal and on some trucks very close to the charge air hoses.They have a lip that can cut into the boots and create leaks.The lip can be bent down to get rid of the cut risk and gain clearance.Once your visual is completed grab an 11 mm tool and check torque on all the hose clamps of the CAC system,you will find clamps that are not tight enough.The hose at the passenger side nearest the innercooler is the most likely to be a problem.

 

[gtwitch]

I have had the rubber boot from the turbo to the intercooler come loose a couple of times and loosen the clamp and put it back in place and tighten. l think at 220 k I need to get a new set of the blue silicone boots and replace mine.

gtwitch in wyoming

 

[rotohead]

Do you have a boost gauge installed? I had a whistling sound that was hard to id until I looked at the boost line going into the manifold (plug behind the fuel filter). It had worked loose just enough to cause a whistle under moderate power. Drove me nuts.

 

[JDoiron]

I found the whistle or should I say the people that had just change my VP found it. After building all sorts of testing fixtures with no luck, I brought it back to the VP repair shop. They had assured me that nothing they did would cause a whistle. Well, after less than an hour they called me to come pick it up with no charge. They said they found a loose bolt and just tightened it. I do not know what bolt they found loose, I am just glad the whistle is gone. Thanks to everyone that replied.