Exhaust Leaking Sound

[78Southwind]

When I bought my 7.3 PSD Excursion (used) it had an up-pipe leak so I installed the International Bellowed up-pipes and all was good. Since then the only thing that I have added is gauges. Now I am starting to hear what sounds like another leak, I didn’t notice it until about 6 months after I installed the new up-pipes. However, I can’t remember if it was before or after the installation of the gauges so I will check the boost gauge and line. The sound isn’t as loud as the original leaking sound and I can’t find any soot on the up-pipes. However, I took a mirror and found a very small amount of soot that outlined the exhaust back pressure shaft on the exhaust side of the turb. Do any of you have any experience with this? What could it be? I checked the turbo a couple of months ago though the blades are worn there didn’t seem to be any play in the shaft. Also, could the EBP butterfly be partially closed and causing the sound? If so how do you check for this?

[StormTrooper]

It could be the EBPV engaged causing a loud hissing noise. It freaked me out when I first heard it on mine, I thought I had a major exhaust leak or like a wastegate stuck open. Then I read up on the post in the 7.3 Tech files and read what I was hearing was normal.

[78Southwind]

Originally Posted by StormTrooper

It could be the EBPV engaged causing a loud hissing noise. It freaked me out when I first heard it on mine, I thought I had a major exhaust leak or like a wastegate stuck open. Then I read up on the post in the 7.3 Tech files and read what I was hearing was normal.

Yeah, I have heard that noise before (loud hissing noise) but this sounds more like a slight ticking sound like an exhaust leak.

[78Southwind]

So I took my tune (SuperChip Tow Safe) out yesterday and the noise is very faint. So is this just increased backpressure that I am hearing? I had my Dad listen to it and he said it sounded normal to him. I also had my buddy listen to it and he said that it sounded like an exhaust leak. I really don't notice any power loss though.

[78Southwind]

Well I checked the clamps to the Y-Pipe and Exhaust Down Pipe today and they seemed tight and I don’t see any black soot. I also checked all the Turbine Housing Bolts that I could see and didn’t see any that were backing out.
I am still curious about what it could possibly be that is causing this exhaust leak sound, so I took a mirror again and found a very small amount of soot that outlined the exhaust back pressure shaft on the exhaust side of the turbo. This time I took a picture of it so that you guys can see what I am talking about. I am wondering if this is what is causing the noise and if the soot outlining the exhaust back pressure shaft is normal. Anyone?

[78Southwind]

Well I checked the exhaust manifolds today and I found some soot, so I am sure this must be where the noise is coming from. Also, I don't have my shop manual with me what do the bolt/nuts get torqued to?