Morning all... Since May this year, when my EGR valve imploded, I've been having a 'mare with coolant loss from my 2004 C5 Avant Final Edition 1.9 TDi multitronic. See the following threads: http://www.audi-sport.net/vb/a6-s6-allroad-forum-c5-chassis/158523-1-9-tdi-flatlining-limp-mode.html http://www.audi-sport.net/vb/diesel-forum/170659-egr-cooler-gone.html http://www.audi-sport.net/vb/diesel-forum/161246-major-issues-following-egr-failure.html So far this year, I have had the following checked/ replaced/ repaired: May/ June - EGR Valve failure EGR Valve (this disintegrated, resulting in the screws and spindle ending up in one of the cylinders) Cylinder Head Gasket/ Bolts (required after checking the cylinder/ piston for damage etc as a result of the EGR failure) Timing Belt/ Water Pump etc (60,000 mile service, including brake fluid change, filters etc) Oil Cooler (this failed shortly after the EGR, resulting in oil mixing with the water) October - Coolant levels constantly dropping, about 1" per month from the expansion tank since June. Coolant system pressure tested by VAG centre in Dunfermline. No external leaks found. Heater Matrix checked for leaks, none found Multitronic gearbox oil checked for glycol - negative result (rules out gearbox oil cooler) New EGR cooler recommended by VAG - some white smoke on start up for a few minutes. New EGR cooler fitted by Star Performance in Kirkcaldy (for obvious reasons!) There is no water in the engine (no froth/ emulsified oil on the filler cap and oil levels within the normal range) So, can anyone here make any suggestions as to where the coolant is going? I've already spent the best part of £2500 getting all of this done (that includes the service and MOT, which it just passed) and I'm completely at a loss as to why the coolant is disappearing. Please help if you can! Cheers, A.