Coolant Loss. Dip stick clean, and no leaks

[RG67MA]

I've got a 1990 with the 4.0L and the AW4 with the original closed cooling system. Early last year I replaced radiator because it developed a pin hole and installed a new Mopar thermostat.

It's been running great until now. I need to top off the coolant bottle every day. No coolant drips on ground. The oil dip stick only has clean oil on it. I do smell coolant from the engine area when I open hood.

Any ideas on what could be going on?

[RG67MA]

One more thing...I pressure tested the system yesterday and the pressure drops slowly, but no obvious leaks under pressure.

 

It had a 16 radiator cap on new radiator last year, but it would weep, so I replaced it shortly after (May 2024) with a 20 and the weeping stopped. It is not weeping from cap now.