"Siren" sound

[kneedragger627]

We are taking the truck from Alaska to Missiouri hauling 2 motorcycles in the bed and a 6x12 Uhaul in tow. not really that much weight. As we were leaving, the code for underboost came on and we determined that the EGR valve was bad. It was covered in carbon and was stuck open. We replaced it but now we are hearing a loud sound, almost like a siren, everytime we go up a long hill. Same sound whether in tow/haul mode or not. It almost sounds like a fan kicking on. All the gauges look good. No spikes in temp or anything. Stock gauges. Any help would be appreciated. Almost back into the US and i wont be able to get back on here until then.

[southend]

Exhaust flex joint cracked/lose clamps, turbo boots loose/busted.

Sent from my SCH-I500

[forddieseldoctor]

I've seen a bad gasket on an egr valve do this. Basically any exhaust leak between the heads and the turbo can give you a whistle noise.

[kneedragger627]

UPDATE:
The sound seems to fluctuate with the RPM. Higher the RPM, the louder the sound. Also, the AC seems to be running non stop. Even when I have it in what i assume is just the vent. Maybe its just that? It seems like it'll make it to Missouri where I can have it checked out. I'll keep updating with whatever I find out.

[forddieseldoctor]

If you have your a/c on the mix setting where it mixes between vent and floor it will run the a/c. Look in your owner's manual if you don't believe me. And it will also run the a/c on either defrost setting.

[southend]

Originally Posted by forddieseldoctor

If you have your a/c on the mix setting where it mixes between vent and floor it will run the a/c. Look in your owner's manual if you don't believe me. And it will also run the a/c on either defrost setting.

I believe he is saying the "vent" setting, that will not run the compressor, it just lets fresh air in.

Sent from my SCH-I500

[southend]

Originally Posted by kneedragger627

UPDATE:
The sound seems to fluctuate with the RPM. Higher the RPM, the louder the sound. Also, the AC seems to be running non stop. Even when I have it in what i assume is just the vent. Maybe its just that? It seems like it'll make it to Missouri where I can have it checked out. I'll keep updating with whatever I find out.

Originally Posted by southend

Exhaust flex joint cracked/lose clamps, turbo boots loose/busted.

Sent from my SCH-I500

I'm still saying this.

Sent from my SCH-I500

[forddieseldoctor]

Originally Posted by southend

I believe he is saying the "vent" setting, that will not run the compressor, it just lets fresh air in.

Sent from my SCH-I500

Some people call the mix setting vent.

Originally Posted by southend

I'm still saying this.

Sent from my SCH-I500

I fully agree that it's an exhaust leak before the turbo.

[kneedragger627]

I called a ford dealership on the way down and talked to a service tech. To him it sounded like some kind of fan cooling off the clutch since it was working harder to pull the trailer. What do you guys think?

[forddieseldoctor]

Originally Posted by kneedragger627

I called a ford dealership on the way down and talked to a service tech. To him it sounded like some kind of fan cooling off the clutch since it was working harder to pull the trailer. What do you guys think?

I never thought of that, but I have heard the fan kick in dragging around some trailers with a 6.0. I guess I wouldn't have described it as a siren though. But it makes perfect sense to me. I guess I missed the part about pulling a hill with a trailer.