LPG in radiator?

Here's a new one.
Mate has a GQ with LPG, last few weeks, after a long trip, the coolant fills the overflow bottle and leaves air in the top of the radiator. When the radiator cools it doesn't draw the coolant back in. When you open the radiator it lets out air under pressure and is low on water. Had it checked out by radiator place, found all to be well. Last trip we took both our GQ's just in case, sure enough it did it again. When I opened the radiator cap I got a distinct smell of LPG, mate couldn't smell it. Seems to me the gas mixer is leaking LPG into the coolant andforcing the coolant into the overflow bottle, is this possible?

I have never heard of it, but just did a search and found this: http://www.squaredarches.com/phpbb2/...php?f=7&t=1215

So I'm guessing it is very possible

Sounds like a blown head gasket to me. Fill the radiator and run the engine with the cap off. Look for bubbles in the top of the tank. Best not have a fag while you do this one.

First thought was blown head gasket, but only blows bubbles on LPG, was so tempted to put a match to the air in the radiator, just to satisfy curiosity. LOL.

Yes very possible as the converter uses the hot rad water to convert the liquid lpg to a gaseous state.