My 2005 Blazer runs good, have had no problems with it in the 9 years I have owned it. But it is leaking Coolant. Not a large amount but enough to require monitoring.
I can not see exactly where the leak is coming from - but I can not see the water pump. Any suggestions?

 

A cooling system pressure tester would be helpful, most auto parts stores rent them. Pressurize to 15psi and look for leaks. Very common on the 4.3L to leak at the lower intake manifold gaskets. There are coolant passages at each end of the cylinder heads, both sides, and they like to leak where the intake manifold bolts to them. Very common to leak under the AC compressor making it difficult to see.