Undetectable leak in radiator?

Yesterday after driving my 1990 Integra ~ 25 min (Fwy), upon parking at the Farmers Market, I noticed the Fan running, which it usually NEVER does, unless there are impending issues (like in the past, when I needed a new radiator). I also noticed a weird smell, and even a stronger than usual gas smell coming from near the engine area, but thought it could have been from other cars near me that were coming and going.

This morning I opened the radiator cap and found the liquid slightly low, but there was still stuff in the overflow reservoir.
There are not ANY signs of leakage under the car, but I now think the smell I noticed yesterday WAS radiator fluid.
The hoses all look fine and the radiator is only a year or so old.

FYI, I tried to search Radiator queries under Repair and Maint. and the "ask a question " section, but it is not giving me the BLUE links that I USED TO GET, (as in others on the forum who posted radiator problems), but rather the links are RED now, and when I click on them, it often comes up as UNTRUSTED site, so I don’t want to go there! Maybe the format has changed and it is ALL like this?

If you can’t detect any leaks, and if you don’t know that the radiator pressure cap was replaced when the radiator was, the problem could be with the pressure cap.

Pressure caps are designed to open at a certain pressure. This is somewhere beween 14-16 PSI. If the pressure cap is defective where it’s opening at 3 PSI this allows the coolant in the radiator to escape as a vapor which causes the smell.


Perhaps put a piece of cardboard under the engine as you park it later so you can see whether it is indeed leaking antifreeze.
Weep holes can be really small so you may not be able to see it unless you look closely. It may only bleed when the system is pressurized, like when you’re running. Inspect especially the top radiator hose, if you don’t see any evidence of it leaking coolant. If that weeps, it will spill on to the engine, causing it to burn and smell quite strongly.

It could be leaking onto the engine and evaporating. Worse case, there could be an internal leak in the engine, with the coolant getting into your oil. Make sure the oil isn’t milky looking.