On the 3.9L V6, 5.2L V8 and 5.9L V8 the Oil leaks commonly from the valve cover gaskets, intake manifold gaskets (front and rear), timing cover gaskets, distributor O-ring, and the rear main seal area. Using fluorescent engine oil dye can be helpful in determining the source(s) of the oil leak.
The AC/heater (HVAC) system may unexpectedly switch to the defrost mode when accelerating. This system is operated by engine vacuum and should be inspected for any vacuum leaks if this problem develops. There is also a revised vacuum check valve available to address this concern.
Some vehicles may exhibit one or more of the following: Spark knock complaints when the vehicle is under load, various single cylinder misfire, and surge in 4th gear (around 45 mph). Our technicians tell us that rerouting the coil and spark plug wires to minimize induction effects will commonly correct this condition. If wires must cross during the reroute procedure, they must cross at a 90 degree angle.
A surging or bucking during acceleration can be caused if the distributor is moved or mis-indexed. This is a result of the cam and crank position sensors being out of synchronization. Wear of the oil pump drive gear can cause similar symptoms because it allows excessive free play in the distributor drive. The distributor drive gear and bushing should be replaced if the rotor tip moves back-and-forth more than 3/16th of an inch when checking drive gear free play.
The door glass may separate from the glass lift channel. Our technicians tell us a front door glass channel kit is available to repair the door glass. The repair involves removing the door glass from the vehicle.
Delayed transmission engagement of 2 to 8 seconds may be noted after the vehicle has been parked for an extended period. Our technicians tell the repair involves installing a drainback relief valve in the transmission oil cooler pressure line.
A delayed upshift condition may be experienced for about 1/4 mile in cold weather (32 degrees F and below) and is most noticeable after the vehicle has been parked for 8 or more hours. Our technicians tell us the repair involves replacing teflon governor drive seal rings with cast iron seal rings.
Hard Starting, Rough Idle, Black Exhaust Smoke, Poor fuel mileage may indicate a leaking injector or more commonly a leaking injector O-ring. Our technicians tell us that with engine idling and air cleaner removed, look into the throttle body with a flashlight, If fuel is seen dripping from around the injector, the O-ring is likely faulty. If fuel is dripping from the injector nozzle, replace the injector.
One the 3.9L V6 and 5.9L V8 the carbon buildup on the top of the piston is common. As the buildup increases with mileage and over time, symptoms may vary from light ticking, to ticking/hammering, to hammering/knocking noises. Fuel injector cleaner often solves the problem.