I took my 2000 Sable 24V Duratech to the dealer for the exhaust smell I noticed when the car was stopped and the heat was on or (to a lesser extent) the AC
They found nothing (which blew me away, since I figured they would want to sell me a new exhaust system - Freedom Ford, Norfolk VA.)
I actually bought a carbon monoxide detector, with a digital readout to measure the CO
in the passenger compartment, but there was zero.
So, I took a second look at the engine and noticed that the rubber elbows on BOTH crankcase breather tubes had rotted away. The elbow on the rear cylinder bank was completely broken and the tube was dangling from the other end where it connects to the throttle body.
The front elbow had 1/4 inch hole on the underside where you wouldn't normally be able to see it.
I replaced both elbows, using old spark plug boots that had a right angle bend and they fit perfectly.
Replacing the PCV
breather tube elbows (PCV
vent) solved the problem, no more smell.
Both tubes connect the throttle body and are about 12 inches long. The other end, where mine rotted away, connect to the top of the cylinder bank valve covers.