Mystery antifreeze leak

My 1997 Olds Regency occasionally leaks antifreeze, usually after I run the heater on the way home from work. I park it and then see antifreeze dripping from underneath the hood,passenger side, midway to the front. The mystery is my repair guy pressured up the system and could not make it leak! Any ideas where it is coming from?

If its the 3800 engine, it could be the intake manifold. they are prone to cracking.

You win the prize. It finally started leaking big time and I had to replace the water pump AND the plastic intake manifold.

And the problem probably stemmed from DEXCOOL coolant.

no cigar for you.

The gasket collapses around the bolts, the bolts become loose thus allowing air to mix with the Dexcool and mix with the engine oil.