General Intermittent exhaust leak

[dgdsm]

I described in another thread how I have this intermittent exhaust leak that I can smell. A Seafoam treatment came up with nothing, so I've been looking around for other ways to find it. Now I actually took off the head 2X when working on the engine in 2013-14, and when I put it back together the second time I reused the exhaust manifold gasket from the 1st time. So I've been suspecting for a while the exhaust manifold gasket. I think I found the leak today with the soap-and-water spray bottle method:

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This one's shot with a cell phone so not the greatest quality, but you can see the bubbles at 1:27 and 1:47. So my question is, should I definitely be looking to replace the exhaust manifold or is there some other explanation for the bubbles at the weld point at 1:27? From my scantool/ live data, the engine is running a little lean: Sometimes LTFT at about +7, sometimes climbing up to +12.5 at idle, which I think is all from exhaust leak(s).

Also I'm not too sure about the sound of the engine in this video, which sounds to me like chugging or maybe lifters. This is the engine at idle from a warm start.

 

[dgdsm]

A little update: I picked up an infrared thermometer off Ebay ($7.50 !) and have been using it to check out different parts of the manifold and exhaust and cats. It looks like the temp varies wildly at different places where the manifold meets the head, some places 500F+, other places about 300F. The same spot that reads 500F+ at one point can read 300F a little later. I'm thinking right now that gasket and manifold are both bad, definitely the gasket in any case.

If anyone has some experience with infrared thermometers and exhaust components let me know.

 

[Silent_White]

you cant check for exhaust leaks with soapy water.... those bubbles are because the water is boiling

 

[mike96]

You can try using a mirror to find the leak. It works better if the mirror is cold, like when you pull it out of the tool box first thing in the morning after a cool night. Run the car and hold the mirror close to any and all places you think there might be a leak. The mirror should fog up like when you breath on it. I have done this in the past with good success. I do think it works better with some humidity though.

 

[dgdsm]

I found the soapy water spray method on some YouTube videos and it's on many online forums including this post on dsmtuners . I think most of the video I shot shows boiling water, but the bubbles at 1:27 and 1:47 look to me like gases coming up from the manifold or gasket. But OK, I guess it could be boiling water at those points too.

I have also now a mechanic's stethoscope, but I don't know atm what the exhaust is supposed to sound like to know what's abnormal.

A few days ago I tightened up some of the nuts on the manifold ... a couple of them are hard to put a torque wrench on and I guesstimated those with a flare nut wrench (two years ago). I'm not sure how adding a few ft-lbs of torque to those nuts could make a difference, but I think it did.

And LTFTs are better: Holding steady at +7.2 at idle, and pcm pushes it down to around +4 while driving.