I have a 2003 4wd 4.7 Durango. I still love it. It just hit 140K miles. I would like to keep running since I will be sending a kid to college soon. Short history: Exhaust manifold studs (twice). Musical chairs with crankshaft position sensor. (Has original OEM now). Bosche Platinum plugs put in 60K ago. (probably time eh?) Water pump at 108K not because it went bad but a friend's Dakota pump died around that mileage. Enginewise nothing serious. Still has original starter and alternator. Factory battery lasted 8 years! Always garage kept and driven by a stay at home mom. Concerns: Misses when fired cold for about 1 second. How long to injectors and ignition coils last?

 

Think I would change the plugs, and go back to the factory recommended flavor. I know on some of the trucks, rare-earth plugs are a crap shoot, and have been the culprits in mystery mis-fires.......

 

140K is low miles for a 4.7L. The most important thing in the longevity of this (and any) engine, is religiously checking the fluids and avoiding overheats. I run NGK V-power plugs and Quaker State Ultimate durability 0W-20 in the crank-case. Use Mopar coolant. It has silicates to prevent head small gasket leaks, which can eventually turn into big ones. Tranny drain and fill are also equally important. I drain mine every 25K and I installed an aftermarket drain plug to prevent from pulling the pan each time.

 

4.7 will last long beyond what you have on it with only basic maintance, my only suggestion is agreement with the comment about the platinum plugs, GET THEM OUT, they are a very common cause of misfires in the engine, especially if you do alot of city type driving, the coppers work fine and the plugs are easy and quick enough to change.

 

Here's a good suggestion, replace the radiator hoses before they break! I blew out an upper hose and it overheated, eventually causing a dropped valve seat.