Finally got the motor stripped down to the short block to reveal the damage…pistons 4 and 8 from the left bank are toast.

tough to say what caused it, my best guess is that I had a massive crack in the intake tube and unmetered air getting into the intake caused a detonation. Timing gear was in perfect shape on left bank where the piston damage was. Right side a bit loose.

miraculously, cylinder walls and conrods are perfect, as well as the cylinder faces on the other 6 pistons. The faces of the valves for cylinders 4&8 are beat up, but valve stems are all perfect.

Canvas is a 2011 XJ Supercharged SWB with 74k miles, and otherwise in cherry condition.

Planning to rebuild back with performance mods to be a weekender for spirited, country road driving in the piney hills of northeast texas.

Thanks in advice to @davetibbs , @tapps33 , and other contributors, that have allowed me to plan this rebuild.

Hopefully I can add something of value along the way.

pics below:

Notice how piston damage is nearly identical on both pistons

 

I am amazed you didn't have any ECU codes before that damage was done.

 

Are you just going to swap those two pistons/valves and do all new gaskets or are you going to go full rebuild with bearings and everything?

 

@lotusespritse I thought the same thing, but I guess the reason would be because the crack in the intake occurred on the engine side of the iat sensors.

@AldoRaine , I’m still trying to decide how I’m going to repair it. The car is in great cosmetic shape inside and out, and it deserves to be done right.

right now I’m leaning toward only replacing all pistons and rings. Not sure whether to go with KOLBENSCHMIDT off the shelf ($700) or custom forged Mehle pistons ($2,000).

Thw engine turns over like glass, so I’m struggling with the notion of pulling the crank given the difficulty of sourcing fasteners for the mains.

I’m going back and forth even as I write this reply. On one hand there the “if it ain’t broke don’t fix it” advice. The. On the other hand, there’s the “while you’re in there” advice.

if I pull the crank, I will obviously need engage my machine shop, which I should probably do anyway.

As far as the heads go, I’ll probably replace those 8 valves in the damaged cylinders, and redo all the seals and lap the sealing surfaces while I’m there.

I will definitely update the thread with how I decide to go about it.

 

I had an air leak on the back of the intake for our 3.0L S/C on the Range Rover where the symposium connects and it set off all sorts of misfire and lean codes.