Intake fails = Fuel/air cannot enter, cylinder does not light, fuel puddles against intake valve, reversion occurs in the exhaust manifold due to failure of valve overlap, nothing really happens until the fuel floods the intake and runs to other cylinders, or something causes ignition and you no longer have an intake manifold

Exhaust fails = Fuel/air enters, cylinder lights, exhaust doesn't escape, more fuel/air enters, cylinder lights, exhaust doesn't escape, fuel/air ent.......[repeat several times]....more fuel/air enters, amount of unburned fuel/exhaust creates significant pressure and gradually fails to compress, fuel/exhaust escapes past the piston rings to the crankcase, more fuel/air enters, piston can no longer compress the charge, connecting rod bends or exhaust gasses run back out through the intake valve when it opens, hot exhaust gasses pre-ignite fuel in the intake runner, you end up with either a bent connecting rod or you no longer have an intake manifold.

First set - One of the 7/16 bolts into the head came loose, allowing the shaft rocker assembly to flex upward as the valve spring compressed. After enough times, it snapped off, ripping the bolt right out of the head (along with 2 others)

Second set - one of the 1/4" bolts came loose, allowing the rocker arm to pivot upward. Once the loose bolt broke, it bent the second bolt. Luckily it didn't bend the connecting rod, but it trashed the piston rings. With the exhaust valve failed, the intake valve was unable to open due to the cylinder being hydrauliced, so the pushrod punched the 3/8" adjuster right out of the rocker arm.

https://photos.app.goo.gl/RAj29ad1erymaRmFA



https://photos.app.goo.gl/GJCkNSt3QR2yxNaE8



https://photos.app.goo.gl/ZawBe3iuz9dvCM9i7



https://photos.app.goo.gl/2PVLkZmb81QZYat76



https://photos.app.goo.gl/PA1jfoZ8FPqeAYwd6



https://photos.app.goo.gl/mB5SbFDWcC3JYSDV9

 

Thanks, Magnet. That's a bit of carnage there. And to think that I drove the truck almost 30 miles . Well, mine was an intake valve rocker that got ejected, so I'm pretty lucky.