A little off point here, but whilst you got everything apart to fix lifters and/or plenum, also replace your valve stem seals with good quality ones. Mine cost me $11 (felpro) on rockauto...5.2 magnum. My oil consumption went from 1 qt every thousand miles, to now, 1/2 qt per oil change, n half of that is in oil catch can, lol. Sometimes I go 4000 miles if I do alotta hiway driving.

 

that's a good. Never done valve stem seals before. Do the heads need to come off? Wish I had more money or I would just replace the heads with aftermarket ones that shouldn't crack. Although mine don't show any symptoms of cracks anyway.

 

Heads don't need to come off. Valve seals aren't difficult, just tedious. There are 16 of them..... Hardest part is making sure you don't drop a valve into a cylinder..... Easily solved with either some cotton rope, (not synthetic please, cotton fibers will burn off, synthetic fibers do not.) or an air compressor.

 

Heyyou's rite. I used 'le rope de cotton n that was the easy part. Getting valve no's 5 n 7 were a gigantic PITA cause of the brake booster. I remember thinking, after it was all over, how relaxed and calm I felt for a job well done. What really pissed me off was trying to retrieve that damnable screwdriver that I embedded in my garage wall. Who knew I could throw that hard, whilst screaming obscenities that were actually, upon reflection, prolly not grammatically correct. Ah well.

 

Another question. What does spark knock sound like? Anything like what is heard in my video? The noise I am hearing is strange to me because it doesn't do it every time I rev it. Only if I quickly give it gas. If I slowly lean into it it won't really do it.

 

Spark knock sounds a lot like shaking a can full of marbles.

 

Did you ever find out the problem?

 

No. I ended up finding out that someone had swapped in a 5.2 into it so the noise was comjng from a 5.2. I have since fully rebuilt a cammed 5.9l and... even that has a strange valvetrain noise😂 runs strong tho

 

Well that's interesting lol. I have the 5.9 with 282k and it has what sounds like valvetrain tapping when cruising in town or on the highway. It also has the hiss and stumble at idle. The intake hat was missing the gasket so i put one in. I did a lot of reading on the hiss and stumble at idle issue and people were saying after they replaced the o2's that the issue was fixed, despite the computer not throwing a code for the sensors. Any thoughts on that?

I plan on inspecting the valvetrain. Great info here about replacing stem seals whilst in there! It does consume a lot of oil. Nothing leaks and no visible smoke so it has to be going somewhere..

I was just curious about the noise and thought I'd sit here and see if anyone comes up with a definite answer while i contemplate a rebuild.

What do you guys mean by blown intake? Are they known to crack apart?

Edit:
**Just found the "end all be all" plenum sticky thread

 

The PCM has no real way to tell if the data its getting from the O2's is correct or not. So long as the heater circuits are working, and the PCM sees voltage from the sensor switching hi/lo, it believes everything is good. Trouble is, while it LOOKS like it is working properly, the sensor could be misreading the exhaust, giving bad data to the PCM, and the PCM adjusts injector pulse width according to that bad data. That can give you a rich, or lean condition, (depending on which way it errors) and the engine just won't run right. Easy test is to unplug the front O2 sensor(s), (how many you have depends on year, and federal or cali emissions.) and go for a drive, if it runs better, replace the sensors.