Coolant Odor In '05 330

[DavidKDenver]

Lately, I seem to be getting a faint, musty odor of coolant while using the heater - and right now, that's just about all the time.

Could I have a leak in a heater core? I don't see any mist from the vents which occurred in another vehicle many years ago. Otherwise, what else could cause this?

[RX in NC]

Your could certainly have a heater core leak, but one of the most common coolant leaks is a pinhole breach of the head gasket in your engine (some call this a blown head gasket when the leak is so bad that your engine continues to run even after you shut it down because it has overheated to the point of driving itself on compression almost like a diesel). You can sometimes smell coolant in your cabin when this occurs. Are you losing coolant? Have you checked your overflow container?

The best method to use to determine whether or not you have a leak in your head gasket is to have someone start your vehicle while you observe (and smell) the tailpipe area. If you see an initial burst of steam (not smoke) and if you detect an odor of burning coolant, chances are that you've got one.

The most common cause of leaking head gaskets is running your vehicle on too low a coolant level. Over time coolant evaporates and must be checked and replenished in the overflow container. Most owners probably don't do this on as regular a basis as they should. I glance at all coolant levels every weekend at the same time that I check the oil levels and tire pressures.