• Ford Taurus engines are generally reliable units, but many do suffer from one serious flaw. Because the castings and base mating surfaces on older aluminum heads (1992 through 1995 3.8L V6s and 1996 through 2000 3.0L V6s) tend to be thin, they are prone to cracking when overheated. The symptoms of a cracked head and a blown gasket are similar, and it is often difficult to differentiate between the two.
  
  

White Smoke

• One of the most common tell-tale signs of a cracked head is white smoke coming from the exhaust pipe, which is actually steam caused by an internal water leak. Some amount of white smoke will indicate either a cracked head or blown gasket, depending on where the crack occurred.
  
  

Oil Smoke

• Blue smoke coming from the exhaust pipe that smells like burning oil usually indicates a crack in the head. This is especially common on four valve-per-cylinder cars (16 valve fours, 24 valve V6s and SHO V8s), which can crack along the valve guides and allow oil to leak. On V6 cars, this can also indicate a blown intake manifold gasket.
  
  

Water in the Oil

• Many head cracks will cause cross-over between the oil and engine coolant. As oil rises to the top, it tends to accumulate in the radiator and is often visible when the cap is removed. You'll have to wait until after the car cools down to check for this as the oil can emulsify when the engine is running.
  
  

Misfiring

• A cracked cylinder head will almost always cause some sort of cylinder misfiring, which creates shaking at idle and loss of power under cruise and acceleration. When tearing the engine down, one sure sign of a cracked head is one or two adjacent cylinders or pistons that are markedly cleaner than the others. Leaking coolant turns into steam in the combustion chamber, which does a nice job of removing varnish from the affected cylinders.
  
  

Coolant Gases

• Depending on the particular year of Taurus and the location of the crack, exhaust gases may accumulate in the coolant system. This can be visibly diagnosed by removing the radiator cap and looking for constant bubbling in the coolant, which may or may not be accompanied by the smell of exhaust. However, in many cases the exhaust-to-coolant crack isn't large enough to cause visible bubbling, which is why any well-equipped shop will have a gas analyzer to check for it. The procedure involves sealing the radiator cap off with a gas sensor and testing for the presence of engine emissions.