I get an occasional antifreeze smell when I'm driving, Checked for possible head gasket problem, nothing, looked for leaking fluid around the engine and heater core, nothing, no leaks. WTF?

 

possibly coolant reservoir/overflow bottle venting to atmosphere.

 

X2

 

Sometimes when the heater core starts to leak, you will get atomized coolant through the heater vents before it actually starts leaking liquid coolant. Are you smeeling it with the heat on/off/or both?

 

I kinda have the same problem, I smell it all the time through the vents. AC on or off and my heat is not very hot.

 

You have a leaky heater core

 

If it leaks it will fog the windows with an oily film over time. You might put a newspaper down in the passenger floorboard and see if anything leaks on it after a couple of days.

If the coolant smell only comes from the outside, then see my post above.

 

After smelling an antifreeze odor around my '87 for several months, the coolant reservoir (football) split open from an apparent hidden crack. I barely made it home.

 

I was replying to the guy that said he smells it through the vents. If its coming through the vents but you can't smell it under the hood, its the heater core. As heater core leaks get worse, they will start to cause the window to fog and then get bad enough that the pass side floor boards get wet.

As for the OP's problem, pressure test the cooling system just to be sure there are no leaks but it is probably just the overflow venting pressure. Keep an eye on it for sure though.

 

I have a 91' 4.0. I have had it for about 10 years now.. I would occasionally have that smell.. it ended up being the heater core switching valve, it is vacuum actuated and when it would turn on a little fluid was leaking from the actuator arm on the outside.. cost about $8.00 and took about 10 min to replace. Hope this helps.

 

I had a freezeout plug rot out behind the flywheel. That made a smell.