I recently replaced the heads on my 2500 1998 V8 magum 160K miles because it had a hole burnt thru the exhaust valve # 8 cylinder. The truck ran really great for 1000 miles and then the CEL came on and the codes were for misfire detected on cylinders # 5 and 6, I was baffled because the engine was running really awesome at the time except a very little stammering at idle that it has had since it was new. As time progressed a noise was noticeable while accelerating under load that was similar to a exhaust leak, every time I have tried to locate the source I cannot here the noise in the engine compartment or from below. It also seems I need to drive a bit before I can hear it. It has gotten worse with time and I have stopped driving the truck except for times of dire need for fear something is going to be damaged badly.
I have checked the compression on # 6 cylinder and it is 135, however with a leak down test I couldn’t get it to hold air until I loosened the rocker arms no matter how I bumped the engine there seemed to be no spot that both valves were completely closed is this normal or is there a possible problem in the camshaft and or valve train? Sometimes when I am driving the noise sounds like it may be a lifter or something like that. I can repair any thing that the problem may be but would like to know what it is before I start blindly taking stabs it. I used Felpro gaskets and replaced the head bolts with new Felpro bolts when I replaced the heads so I can hardly believe I have a blown gasket but that is the most likely candidate for a culprit I can come up with. In the mean time the idle has gotten a little rougher but my battery went dead a few times and the light resets when this happens it takes a while to come on again I will run a tank or more of gas before the light comes back on. When I had a hole in the exhaust valve it would come on in 5 to 15 miles of driving.

 

Sorry I had the last post saved in word because I have been trying to post unsuccesfully all week. I have more up dated info

I went thru and tested ecery cylinder and they all will hold air if I usea socket and turn the crank by hand it appears the air was pushing the engine backwards to where air would leak outif i turned it back forwards it would seal. not losing air in a leak down test is always good news But it still leaves the ? what is wrong What I do find strange is that the intake valve is still open when the piston is at BDC ready to start compression stroke. I have most of my exp on Chevy and whith them I would know already that I have likely jumped a tooth on my timing chain. Is dodge the same or is that timing between piston and valve normal for them?