Coolant smell in engine compartment

I can detect a slight coolant smell in the engine compartment, yet I can not see a leak. Other symtoms are low temp. according the the temp. gauge approx. 175 ( radiator fans DO kick on) and the heater does not throw has much heat as it should. The is no oil in the water and no water in the oil. I did see a tread which addressed some plastic part in the engine compartment that leaked. Does any know what that might be or am I in the same boat with everyone else looking at the head gasaket? Will the pressure leak test confirm my worst fears?
Please give me some goodnews.
Thanks Jim

Thanks you have updated your profile but for the benefit of all who want to help, this is a 1997....
In as much as temperature is concerned, chck this out
http://www.my-chevy-venture.com/temperature-gauge.html
as suggested by GregA
BUt..the "heater does not throw as much heat as it should" is not something I like to hear.....much too often associated with head gasket failure indeed, a very common 3.4 issue. THis usually combines several symptoms:
- fluctuating temp needle
- fluctuating heat from heater
- requires adding coolant from time to time
- steaming
...so maybe you are just describing some of these...
If this is the case, it will just get worse so at some time, you would be sure of it : just arrange so it does not happen far from home. My brother just has his done a few months ago, a 2002; ...a nasty job, but depending on condition of your car, it can get out better than new....at least that is what they told my brother.
These head gastet problems are all over the car spectrum: GM 3.1,3.4, DOdge 2.7, Subaru outback.....and the list goes on: it seems 100 years of car experience suddenly vanished as these problems were scarce in the 60's and 70's....then just exploded since the '90's...