In August I replaced my UIM and LIM gaskets along with the UIM (including reduced stovepipe with heat shield) and the LIM itself (with the help of many people here). Not long after I started noticing a coolant smell as the engine came up to temperature, then it would go away. I couldn't find a leak under the hood and so I've been operating under the idea that my heater core had a pinhole leak and that was how I was smelling it.

This weekend (after replacing my fourth window regulator ) I found signs of the leak. Small wisps of smoke coming up from the exhaust crossover pipe- at the joint of the front header.

I believe now that the smell goes away because eventually the pipes heat up enough and seal themselves up?

From my understanding that means I have coolant getting into the combustion chamber. I can think of two ways:

1.) Blown head gasket
2.) LIM gasket not sealing

How can I diagnose this further? I used the GM aluminum framed LIM gaskets and torqued it all in sequence? I don't think I can do a head gasket by myself. I'm not sure if it'* the LIM gasket if I should do it myself since I did once and here I am again for round two.

Is there any sort of leak down or pressure check that I (or a dealer) can do to find the source of the leak? The car drives fine - no noticeable loss of power. Possibly somewhat lower gas mileage though - hard to say. I'm pushing 140k on her. (2000 SE)

Any suggestions?

Could the coolant possibly be dripping down from the throttle body gasket?

Or dripping from the thermostat housing or hose?

I always assume the worst. Great suggestions guys. Turns out it was just the upper radiator hose dripping from the thermostat housing. I should known better- any time you put hose clamps on you have to retighten them at least once as the rubber settles. Glad it was a simple fix. Thanks!