If there is a small leak that can be fixed by topping off the coolant, can you live with that?

 

I would guess the third hose you mentioned is the one missing. Anyway... FOUND the leak! The expansion tank has two pinhole leaks from the bottom half of the tank. When the system is at operating temp and press, there are twin tiny streams of coolant spraying out from the tank against the spring tower housing. Already ordered a replacement tank, plus the missing bleed/vent hose, upper and lower rad hoses and a thermostat. Looks like a project day coming up!

 

Replace your plastic T-stat housing with a metal one if you have not already done so.

 

Finally figured it out... on the 4.2L the expansion tank has a factory plugged nipple next to the one that connects to the small hose to the T-stat housing - nothing is supposed to hook up to the blanked nipple. Anyway, found my leak... micro crack in the expansion tank. Replaced it and all is well for now - upper&lower hose, plus T-stat and housing replacement is next. The octopus looks good. Thanks again for your input!

 

Here's one I didn't see mentioned. I had the thermostat housing replaced but still had the bad smell. I finally decided maybe some coolant was laying in the engine valley under the intake manifold. I pumped some soapy water in there and flushed it around a bit. No more smell.

 

You found it!

Whenever mine had a leak from anywhere around the top of the engine, some coolant remains laying somewhere on top of the engine. Good work.

I hesitate cleaning around the engine area, because of a bad experience with getting another engine steam cleaned in the past.

 

Happy you found the leak.

Any coolant leaking from the top usually ends up pooling on the engine valley between the cylinder heads. From there is dribbles back falling onto either side of the transmission bellhousing, and often onto the catalytic converter brackets.