My recently purchased 98 F150 periodically spews smoke from all ports of the HVAC system. This smoke smells oily and coats the winshield and windows with an oily fog that must be cleaned off with a clean towel or it smears. It seems to be worse when it is raining. I have checked the levels of the antifreeze, break fluid, transmission fluid and power steering. All seem to be full with no visable leaking. The truck stops fine, does not overheat, transmission and steering work fine.

I expect I will have to take it to the local dealership, but I haven't had much luck lately with those mechanics diagnosing the problem without several hundred $s of trial and error. They are mostly good people, but inexperienced.

If any one has any ideas where this smoke is coming from, I can point the mechanic in the right direction.

thanks,

 

Coolant is leaking into the HVAC system ducts.

Most common: Heater core or the hoses leading to the core.

A pressure test of the cooling system is in order to pinpoint the leak.

Steve

 

Thanks Steve

I just confirmed your diagnosis. I had not seen any coolant leak prior to this morning. It is leaking near the firewall on the vehicle's right side. I expect this is at the heater core. I hope it is just a hose. The heater plenty warm on cold mornings. I will find out today.

MAJ J