Found some parts of the timing chain guide in the oil pan during an oil change where I was also changing the leaking gasket. Pulled the engine, spec'd out the parts and had some good times working with my dad over a couple of weekends got everything installed and back into the truck. The only non-ford part I had to use was the left front cassette (used Cloye's 9-0444SF). The initial shake down drive was perfect, about 20 miles with no issues and the engine ran beautifully. My son called me the next morning saying he heard a slight whining noise for a second or two and then it lost all power and started vibrating. He pulled over, called me, and I towed it back a few miles to the house. I pulled #5 plug, because it's about the easiest to get to, and shoved a bore camera into the cylinder and saw what might be a valve strike mark, but the camera kinda sucks so it wasn't too clear (or I just didn't want to believe what I was seeing). I popped the valve cover off of bank two and could see the chain was not on the cam sprocket. Shocked the crappy camera down the front of the head and could see the chain wasn't on the jackshaft sprocket either. The chain guide was also chewed to hell. I dropped the oil pan and found plenty of shredded plastic and two pieces of broken broken chain guides that I think came from bank 1 (these are orange/brownish from ford, not white).

I'm at a bit of a crossroads now as I need to get this back on the road (or just replace it) and I need to get my 2016 Explorer ecoboost water pump and timing components changed as it is at the 110K mile mark. I need to dig into the 4.0L more to see if I can determine what actually failed or caused the failure.

I don't guess I really have any questions, just wanting to post the experience and see if anyone else has an experienced similar. I'm thinking about putting a crate long block into the ranger and trading the explorer in for a tacoma.

Some images...


valve cover lifted on the front of bank two, no chain present.



picture of scope camera showing chain resting down next to the lower sprocket that is on the main jackshaft.



The fun stuff I found in the bottom of the oil pan after draining and dropping. Not much metal at all, mainly all plastic.

And unsure if I'll ever get all the shredded plastic out of outter ring of the pickup tube. That stuff seems to multiply ... every time I get a wad off it out there's another wad waiting.

 

As I tear back into the engine I'll keep updating this thread, if for nothing else as reference I might need to refer back to.


I planned to get the engine ready to pull back out after I got off of work yesterday, but I only made it as far as getting the intake manifold removed. Every intake port on bank 2 (same bank the original post images are from) was flooded with a nice oil, fuel, coolant concoction. Hope to have some more time after work today to actually make some progress on getting the engine pulled.


Looking down intake port for cylinder 5, bank 2.

 

I did a complete timing chain rebuild over 50K miles ago and it is still working very well. A timing chain should not just jump off of the sprocket without a reason. When I rebuild mine, the front crank to jackshaft mechanical tensioner was completely broken off and appeared to have been for quite some time. It amazed me that it did not jump off of the sprockets. It didn't even rattle.

I can see if there was some misalignment of the sprockets, the chain could jump off. Other than misalignment, if the sprocket bolts were not torqued properly, they could come loose and may cause the chain to jump off of the sprocket. With the cassette torn up so much it appears there was some kind of misalignment going on. It may be the cassette was defective or installed incorrectly, if that is possible.

 

Images of the piston and head for Bank 2 cylinders.
Pistons 4 & 5 show small valve strike mark I believe. Unsure what all the pockmarks are from. No other sign of broken timing gear. The main timing chain and sprockets are fine and bank 1 is fine.



Bank 2 piston heads and combustion chambers.

 

It is hard to tell in photos. but I don't see valve strike marks. Those pockmarks look like what you ger from detonation. It looks like the same thing in the squish area of the heads. It is strange that only 4 and 6 have them. Maybe they went lean for some reason.