Very first post and it's quite a biggy. I drive a Lag II 2.2 dCi Sport Tourer on a '52 plate with 54k on the clock (mechanic raised his eyebrows at the mileage but the documents line up ok so who knows?) which I bought from a trader about 12 mths ago with around 42k. Had a couple of fuel injection warning lights around Christmas time which after a trip to dealer resulted in a free replacement EGR pipe and a valve clean up. After intermittent fuel injection warning lights every now and again which dissappear when I switch off the ignition and back on again and blowing the dipstick out a couple of times along with some dirty exhaust when changing gear (especially if my timing was a poor), I drove around for a couple of months like a grandad (didn't like to go above about 2200rpm). My 54K service is due so I took it to a local independant Renault specialist that had been recommended. Thats where I got the raised eyebrows. I realise there aren't too many causes of blowing a dipstick, it comes down to blocked breathers or too much blowby past the rings. Bad news was it turned out the breathers were clear. Worse news is one of the cylinders was holding virtually no compression. Valves then? maybe the hydraulic lifters (I'm told) were not operating correctly. Not great but OK lets have a look. Cam Cover and Intake Manifold off (all one unit) and an exhaust valve looks in a bad way. I got a sinking feeling. Cylinder off and the picture is revealed. Detonation on a big scale. The Piston Crown is burned away quite badly including some land. The Bore is scored and may not hone sufficiently to get a good seal in future. One of the Exhaust Valves is burned through around 15% of the circumference and so too is the valve seat. It appears the head itself is too affected to risk trying to fit a new seat. The best guess is a dodgy injector spraying fuel in such a way that detonation occurred. So I may well need to replace either whole engine or might get away with just the head. This is where I need help (apart from being told to look into warning lights a litttle sooner) has anyone any ideas ref where to source good used or recon from? I don't want to give Renault £4k for an Engine or £2k+ for a new Head (excluding fitting). The web wants around £2k for a used engine and I can't track down a cylinder head. Any help would be appreciated on the sourcing and any advice on ensuring the mechanic finds and rectifies route cause and warnings of anything else that might have been affected by this unfortunate failure. Sorry for the essay but it might help someone avoid hefty bill.