Exhaust leak or boost leak?

[gusu]

I have been noticing that my turbo is louder when spooling down when off throttle than when on throttle much like a semi when engine braking. Other than that I have also noticed a slight gargle sound when idling much like a Dodge Cummins, with that turbo spooling sound as well.

This is why I believe I have a exhaust leak more than a boost leak. But I have also noticed my blow off valve is louder than it used to be. I can literally hear faint blow off at only 7ish inHq.

Which also leads me to another question. When you guys are replacing your recirc tube what kind of hosing are you using and where do you buy it at?

If you guys do believe this is a exhaust leak, where do you think it is most likely leaking from? I have also noticed my wideband reads full lean at idle but reads PERFECT when on throttle.

 

[92AWDHX40]

Full lean on your wide and what are the numbers, it wont hurt to do a boost leak anyway to rule that out.

 

[gofer]

A lean WB is an indication of an exhaust leak BEFORE the sensor and sounding like a dump truck and hearing the turbo spooling down is also a good indication. Assuming your WB is in the front o2 location or just before the flex then you can narrow down the leak to everything before it, i.e., exhaust manifold, turbo, o2 housing, and the dp inlet. If you notice a significant decrease in spool time then odds are it's before the turbo, however, if the turbo still spools up like it always has then it's more than likely after it.

Run the Seafoam test if you can't pinpoint where it's at. Sometimes exhaust leaks can be intermittent because things expand after they heat up.

 

[gusu]

A lean WB is an indication of an exhaust leak BEFORE the sensor and sounding like a dump truck and hearing the turbo spooling down is also a good indication. Assuming your WB is in the front o2 location or just before the flex then you can narrow down the leak to everything before it, i.e., exhaust manifold, turbo, o2 housing, and the dp inlet. If you notice a significant decrease in spool time then odds are it's before the turbo, however, if the turbo still spools up like it always has then it's more than likely after it.

Run the Seafoam test if you can't pinpoint where it's at. Sometimes exhaust leaks can be intermittent because things expand after they heat up.

Wow, thanks. I had totally forgotten about seafoam for finding exhaust leaks.


To answer your question iugrad92turbo, full lean on a AEM wideband shows -.- as the reading, as well as full rich. The reason you can tell the difference is because you can watch it lean out or richen up.

 

[gusu]

Thanks again Gofer, I did confirm I had a massive leak on the O2.

The bottom front stud(?) is totally missing the nut.

So now I have more questions. Should I use copper crush washers and where should I get the gasket? Also what would be the easiest way to get to it, I noticed my Megan DP is so large it will require me to remove my oil filter first. Finally what is size/thread pitch of that nut? I don't really know what to call it or where to look in the repair manual.

Thanks again!




*edit* I decided to go with FP's gasket set, new washers from them as well. I found the nut I was looking for is a M10 x 1.25 (14mm head) after finally finding the "What size is that bolt, nut, stud" thread. I decided to not just try to drop the down pipe and get to it that way after realizing my O2 housing sucks for that. Anyway, thanks for the help guys.