Ford 4.2 Engine Problems

The 4.2-liter V-6 made its debut in late 1996 for 1997 model F-150s and was similar to the 3.8-liter version with 12 valves and pushrods. It featured a 3.81-inch bore and 3.74-inch stroke and initially generated 202 horsepower and 252 pound-feet of torque.

From the onset the 4.2-liter F-150 truck was plagued with intake manifold gasket problems. If the gasket failed, coolant leaked internally and caused significant damage. The problem occurred because engines built before Jan. 15, 1998, were equipped with obsolete lower intake manifold gasket. After Jan. 15, 1998, a thicker gasket was installed that provided a tighter seal between the manifold and engine.

Exacerbating the 4.2-liter's problems was a leaking timing cover gasket on all motors installed in 1997 F-150s built through Dec. 31, 1996. Ford recalled those vehicles to effect repairs, but Ford did not recall 1997 F-150s built from Jan. 1, 1997, to May 1, 1997, and equipped with the same gasket.

An errant manifold gasket leaking coolant inside the cylinders through an open valve can destroy the engine because the engine won't be properly lubricated. It also will lead to damage to the bearings. Engine knock is the first sign of internal damage. Most engine failures occur after 80,000 miles.

If coolant is leaking internally, there may be no outward signs of leakage either in the engine bay or on the ground underneath the engine. A simple check of the coolant level will determine the loss of coolant. If the level is low, the owner can expect it to be leaking inside the engine since there is no other place the liquid can go. The vehicle should be towed, not driven, to a mechanic.

The 4.2-liter V-6 engine missing or making a popping noise on acceleration, but may not have a "check engine" light illuminated, may have a coil or fouling spark plug problem. If the engine is vibrating at idle, the problem is likely collapsed motor mounts, which is not uncommon in high-mileage trucks.

It's never a good idea to ignore a "check engine" light. Whatever problem is under the hood will only become worse. The light is an early warning system that something is wrong. It may only be a loose gas gap or an indication of a more serious problem. For example, if the light is illuminated, it may take two or three days for the engine to misfire or hesitate on acceleration. The problem may be a faulty spark plug or wire, which will cause no damage to the engine. But if it's a bad manifold gasket, then coolant is leaking internally and the engine's life is threatened.