4.7 Valve Cover Seal issues
I just wanted to share some of my recent experiences in a thread for others to find easier. I searched this topic thoroughly but found neither of the solutions I required in any of the topics I found.
I first started researching this topic when I noticed my valve covers leaking on my 2002 Ram with the 4.7. I had 270K miles on it and figured they were just dried up, which was partially correct. I purchased a new set of seals from Advance Auto and they came with the individual rubber grommets for each bolt as well. After installing the set, I found that I still had a leak. I searched the topic and found many others had the same problem and had gone thru multiple seals including MOPAR seals at a higher cost and the common final solution always seemed to end with an RTV sealant of some sort.
What I found was that the replacement grommets were too short. Perhaps they are designed for the newer composite valve covers which are thicker, I don't know, I just know that they are too short and did not compress the seal at all. Unfortunately, I had already thrown away the old ones by the time I figured out that I needed them.
Once I replaced the grommets with the correct ones, I still found I had a leak and the only way I could get it to seal was to use an RTV silicone.
I recently rebuilt the engine and have had the valve covers off multiple times looking for a lifter tick and it has not leaked once afterwards, even with the bolts hand tightened. The difference I believe is that the engine is nice and tight with 175 psi compression rather than the tired 145psi that my old engine had. The seals are meant to seal against normal crankcase pressures but when an engine gets worn and the pistons have more blowby, the crankcase pressure can become much higher than normal. The PCV valve and valve cover breathers will vent a certain amount of the excess but once the blowby exceeds what they can handle, pressure will build and the seals are the weakest link.
So, if you find your engine starts sprouting leaks all of a sudden that are stubborn to stop, check your mileage and your compression and keep this in the back of your heads.
Hope this helps.