Following up......The "new" vaporiser wasn't getting particularly warm. We investigated, tried bleeding as we may have got an airlock. NOPE, no coolant at all. We tried a rod down the hose, but didn't get anywhere so we started tracking back.
It seems when they cut the audi water hoses at the back of the engine, they did a crap job. One of the T-pieces was solid, had various glues and sealants and was pretty broken up from over clamping. Swapped it out, recut the pipe and got a good seal (Air pump test first) and then refilled and bled the coolant and it heats up nicely.
It explains why last year I was struggling with cabin heat and when draining, cleaning and filling the coolant i got so much grit out. Think they must have used some form of rad-weld in the system *Shudder*.
And this place that did the conversion in Romania seems to be highly rated!!!
Still, the LPG is now working and doing what it should. It need tuning up, but preliminary tests show it to be a good and capable it. I could floor it and she goes like she does on petrol!
Cleaner emissions and half price 4.2l power awaits