Went out of service 5 months ago due to incredibly leaky valve stem seals, rattling timing chain, and a failed coolant crossover pipe.
Ended up being that all the exhaust valves were bent from the 2 previously failed timing chains. The head spent about 3.5 months at the machine shop with problems cropping up left and right.(parts not fitting, not having required tooling, difficulty finding parts ect.)
So the total list of what’s new: timing chain/ guides, chain tensioner, Vanos solenoid, coolant crossover, turbo housing, thermostat housing, exhaust valves, valve guides, valve seals, spark plugs, cam sprocket, and crank sprocket.
Finished it up earlier today and did about 1hrs worth of driving so far, there is a stumble around idle but outside of that everything is working perfectly, im hoping it’s bad fuel or something and the problem irons itself out. Good news is It’s making more power then it ever has and there isnt a threat of timing chain failure for another 15,000 miles or so.