Cylinders #5 & #6 exhaust valves are susceptible to excess heat due to the head design and the exhaust manifold crossover tube. From what I have read, number 6 is especially likely to burn. I have also read ( tho I find it a little difficult to believe ) that the valves on these engines get tighter with use, not looser. It would fit, tho, that if the valve gets tigher with age and use,, it would eventually not seat completely and allow combustion flame to escape. I'm just patiently waiting for my 3.0 to die. Right now, I'm not having any problems with mine -- 183,000 miles on it (crossed fingers).

Make sure you keept the cooling system in top condition and don't run the AFM too lean. Basically, keeping the engine in proper tune is probably the most helpful. Also make sure the O2 Sensor is operating properly.


Mike in AR