Hissing/squeal and rpm surge

[Jbird]

Two things i want to throw at you guys and maybe figure out if they are related.
The Last few weeks ive noticed my truck will start to squeal or hiss in third gear if i go anything over 2100rpms. Its coming from the up pipes or manifolds, I'm sure i just haven't had time to dig in and cant tell from just looking at it.
My other problem is truck has been wanting to hold third a little longer then normal. When it does the rpms want to jump or surge back and forth about 100 to 150 rpms. This usually in the 2000 rpm area. Under that load you can really hear and fill that oscillation in rpm so it definitely bothers me and hasnt been that way.

Now heres the questions.
Whats the best way to locate exact origin of the leak? It is rather hard to see everything back there. Especially a hairline crack.

Could this rpm surge be connected to the leak? Maybe not getting the correct ebp and its throwing it off? Trans going out?

Any help would be very appreciated.


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[diesel2121]

If the up pipes are cracked you should be able to see soot in that area.

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[sootie]

if you are loosing drive pressure because of the leak, it will hold the gear longer because it isnt making the power it should. yes the epb reading will be telling the vgt to sweep differently to try and compensate for the leak.

 

[Jbird]

No soot that i can find. Cant locate the leak at idle either


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