Hi George
Primarily because ebay is full of secondhand spares and new ones are not that expensive, they are also easier to work on, or at least the 2.0. Hdi is, there seems to be more space around the engine.
I was a little apprehensive to say the least about venturing into the world of common rail engines but the 2.0. 8 valve is a gem. No DPF and the accompanying electronics, basically simple design, actually simpler mechanically than the XUD. The electronics have so far proved very reliable and the engine has covered 200,000 miles on the original clutch, DMF, head gasket and injectors. The road tax is cheaper due to the lower emissions and the fuel consumption is even better then the 2.1 manual with 60mpg+ attainable with gentle driving.
All the engine problems I have had were down to the HP pump pressure regulator which was replaced with a secondhand one although the usual problem with them is that the filter gets blocked.
I also have a 406 estate with the same engine which has covered 231,000 miles virtually trouble free.
Maybe I have just been lucky, the engine problems could have been expensive without the help of the forums and a little trial and error but its so far cost me very little. I did have to replace the radius arm bearings but as I only paid £550 for the car I'm not complaining.
Its not an XM though
Peter
'96 'N' 2.1 td VSX manual estate White RP6695. Sadly gone
2008 C5 2.0. Hdi Estate, Red
2008 C5 2.0. Hdi Estate Silver
Located in Charmouth, Dorset