1998993C2S (did I get that right?LOL)
I am certainly not the best guy to ask. I am only offering my opinion so please don't put much weight on anything that I say. There are some really knowledgable members on here that I am sure could give you some great suggestions as to what to look for. Not to mention that the dealer has the car and cannot find anything either.
I think that you did the right things. If they smelled coolant before they replaced the heater hoses then maybe they fixed it. Although the pressure test didn't find anything. So that would seem to say that there was not a leak in the hose.
Are you smelling it in the cabin but not really outside the car? No obvious coolant level change and no coolant on the ground? It kind of baffles me too that there is no coolant leakage showing anywhere. I am sure that they would have checked all the hoses and they replaced the heater hoses. To change the heater hoses they would have had to remove the plastic undercar cover. So if there was no coolant there either I can see why they are saying return it.
I am not really helping here but just trying to think through it with you.
I guess I would be sure that it is all documented with the dealership. Then I would question them a little bit more to see if they saw any signs of coolant having leaked on the back of the engine or around any of the hoses. At that point I guess I would take the car back and when driving it I would keep a good eye on the temp gauge and watch the coolant level carefully. See if the smell goes away now that the hoses have been changed.
The last thing I guess I would ask them is if they will remove the upper timing belt cover and look down in there toward the water pump to see if it looks wet anywhere around that side of the engine by the water pump. I think that you can probably see down enough to see if it damp there without removing the lower timing belt cover but I can't remember.
If all that checks out I would take the car back from the dealer and just see if you get any more symptoms.
Sorry I can't be of any real help. These things can be very frustrating. Good luck. OH, and I am having a hard time feeling sorry for a guy that has to split his time between Vail and Atlanta
You should try living in Indiana