coolant whiff in passenger compartment - '98 accord v6

I've got a '98 accord ex v6 with very low miles (19,000) that gave me
a whiff of coolant odor in the passenger compartment after running for
about 15 minutes. Heater was on - it was cool outside (about 45F).
No signs of leakage in the engine compartment, no white smoke at
exhaust, and idle is still fairly smooth (the car has always had just
a tad more vibration at idle than I expected, even brand new).
Coolant level in overflow bottle is fine (about an inch above min
line).

I suspect that it might be a small leak in the heater core - although
no other signs like fogging windows, or dampness under dash. Any
other thoughts? Any reason why something under the hood might have
'burped' so to speak? Any simple diagnostic ideas?

Thanks for any suggestions.

-Brian

 

Had any work been done on the car recently? If there's any spillage of
coolant under the hood, from coolant replacement or topping up, it can
smell for weeks afterwards. Usually you'll only notice it in certain
situations, e.g. stopped at a traffic light with heater/fan on.

Things to check: radiator for minor cracks in the plastic tank, radiator
cap for spritzes of coolant around it, heating system water valve and
obviously all hose connections. The water pump also has a bleed hole(s) on
it and according to service manuals it's normal to get very slight weeping
from the hole.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

Thanks George - will check those. It also occurred to me that the
coolant I was smelling was not my own - it could have been from a
vehicle ahead of me in traffic... It was not at all present
yesterday, but I'm definitely keeping an eye (and nose) open.

-Brian