So after standing for several years I've got my little french registered 1984 R4 TL running. The expansion bottle internals were so badly stained it was impossible to see the level of added water (just for flushing and starting purposes). I back flushed the radiator and engine block and discovered that the thermostat had been removed. Once the flushing was completed, new thermostat added, expansion bottle cleaned out and fresh 50 50 coolant added, I ran the engine and took it for a quick trip up the dirt lane outside our house. It ran okay. The level in the expansion bottle dropped and I sorted a couple of leaks at the inlet manifold to cylinder head hose by cutting off the rotted ends, losing about an 1" overall, but which gave me clean ends. Letting it idle for 10 or so minutes, I could detect no leaks from any hose or the radiator. Fast forward 2 weeks and I had time to once again play with the R4 To my horror the expansion bottle was totally empty and even the radiator seemed to only be about half full, I had previously left it topped up to the correct level. No obvious external leaks. I refilled the coolant and took it for a short 2K/M run, after which the expansion bottle level had gone from max to min. No visible external leaks, no steam, from the radiator but the water is going somewhere. The oil level isn't increasing, although there is a tell tale rainbow in water drained from the coolant system. Its losing a fair bit of water but the dipstick doesn't indicate any coolant in the oil, is it likely its just the head gasket or is there the possibility that a liner seal has gone? Its the 845 B1B engine. Thanks George