You already got a good run down above. The basic 3L diesel engine dates a long way back and seems to rarely fail. However, there is everything else.... I am just going through my 35d now and all of the above happened to some degree or other. I am now on the fourth EGR cooler. #1 cracked, #2 the return spring broke, #3 seems to have suffered the internal coolant leak problem (all Hella/Behr units). Just replaced all the vacuum hoses and actuators, makes a vast difference in responsiveness. I cleaned the intake manifold while it was off, caked thick with soot and oil. The MAP failed earlier this year. My current active SCR tank has been good for several years but it is also the fourth one. Harmonics damper also fails around 100k I think.

Thermostats fail every 50k or so...... The DPF needs to be cleaned somewhere between 130k and 150k. I am just trying to sort out if my NOx sensors are still any good. Anecdotal evidence suggests they are good for up to 140k on average. The tension struts on the front suspension fail every 50k or so. The front upper A-arms look way undersized to me and when they fail the car is a pig to drive.

Just returned from a 100 mile round trip into NoVa and these things are incredibly comfy and rumble along very satisfyingly when all is well. Beginning of the year I towed a small enclosed trailer while in Europe, moving some stuff into storage, several 50 mile trips. It tows like a champ.

This is easily the worst car I ever owned for repairs. Even the E53 did not nearly have this many "events" (though the torque converter failing at 93k was a bit miserable....).

So, yeah, breath in deeply before taking the plunge. And even if it seems ridiculous, probably budget 5k in parts to be replaced at 100k and get it over with in one go. Thermostat is easy to check in hidden menu and should be replaced on failure as it affects the glow plugs and GPU.


EDIT: In addition, my shifter stopped working correctly (I figured out what is wrong, easy fix, but still...) and my door seals are all four falling apart.



Enjoy the hunt! :-)

__________________
2003 4.4i black ext./black int./black headliner (kid's runabout)
2014 535d X-drive, M package, silver/black interior

Sold but not forgotten:
2009 E70 35d, black ext./black int./black headliner (sold 2021)
2006 4.8iS Le Mans blue/cream int./black headliner, SOLD in 2012 sadly...

Other hardware:
2015 Cayenne S (wife's new DD and definitely wroooommmmm)
2016 Tundra 1794 edition crew cab, luxo hauler
2005 Tundra crew cab, weekend hauler. Sold after 150k very happy miles.