Hello, I’ve been working on a 2004 f-250 6.0. I had just replaced the hpop and started it up, it ran for a couple minutes then started to make a whining noise almost like a belt. I removed the belt and it kept squealing. So I thought it was a bad turbo, I replaced it and it didn’t squeal as bad but still did. I’m thinking it’s a exhaust leak but would like some help knowing where it might be and how to fix it. Thank you

 

Here is a video of it running at idle

 

Difficult to say from your video. Mechanics stethoscope, wooden dowel, might do the trick to narrow it down. Once you find the noise then the fixing part. If you did the turbo it is a good chance the pipes are not seated all the way. Careful poking around with a listening device in a running motor.

 

The up pipes from the manifold are known to crack at the bellows which could cause a whistle type sound. I’ve heard it can be pretty annoying.

 

Does it change with rpm?

 

I’ve looked and there’s no black suit around the up pipes on the firewall or anything. I’ve heard a exhaust leak before and it just doesn’t sound the same. It doesn’t change at different rpms but it will change in tone just sitting at the same idle. Could it be a vacuum leak? Or a boost leak?

 

Sure sounds more like a boost leak than exhaust. I've had a leak at the collector & it was unmistakable - sounded just like a blow gun on a compressor.

 

Where should I check for boost leaks at? I’ve looked over the cac tubes (or boots) and didn’t see anything big but I didn’t carefully look at them.

 

Unless you can get a look at the boots all the way around you can miss something. I recently had a small slice in a hot side boot. I couldn't see it(maybe with a mirror I might have) or feel it. Taking the boot off you can get a close look. If they have a lot of miles on them they may need replaced anyway. Are they weeping any oil? If they are good, clean the oil off of all mating surfaces and tighten them back down to 108 inch/pounds. If you don't have a torque wrench, in a pinch you can carefully measure how much stud you have showing on the clamp before you loosen anything.

 

Ok I will take them off and check them thoroughly, thank you.

 

No boost at idle, so I wouldn't think you be able to hear a boost leak at idle?

 

@BryanStein i wasn’t sure if there was or not, and the noise happens all the time no matter at idle or driving. But when I drive it, it’s like there’s no power and no boost at all almost like when the cac boots pop off. Just no boost or something that’s what made me think it was a exhaust leak.

 

@Brotherbillstruck I took the boots off and looked at them very close and there doesn’t seem to be any cracks or anything wrong with them. Is there any way I can hook up compressed air in the system and see about any leaks anywhere? I’ve heard people say about smoke tests but haven’t found a machine that will do that yet. Any ideas would help, thank you

 

You can certainly remove them and plug both ends, then thread an air tight air valve in one end to fill with 30 psi air and submerge. But that seems to be lot of trouble for something you can normally find from a visual inspection.

 

Here is how KC Turbos does a leak test with a fitting and shop air on the turbo inlet. I have seen this on the forum here too. Maybe it was Hartwig who put up a picture of his setup.