troopy radiator leak

You probably have cracked radiator top section (plastic). If i where you i would replace whole radiator with heavy duty tropical unit. What you have is common fault with Toyota radiators. As soon as i spot one drop from the radiator i will do the same with mine.

Chuck the plastic one and for similar money you can get a good old fashioned soldered one that can be repaired in the bush if needed. You will have to ring around up there for a supplier.

Common problem even with the older metal radiators in Toyota's, usually the first and second tubes just in at the top on the RHS (drivers side). They always seem to let go at these two points first. If it is a metal radiator and is basically sound have your friendly radiator place chop the offending tubes off and solder them up, you will probably have no more probs.
The metal ones also tend to crack around the seam where the tanks are soldered on too.
If there is any question over the condition of the radiator it would be best to replace it with a new full metal one, radiators are much cheaper than engines.

Glenno.....radiator maintenance in the hands of a pro is quite straight forward....it can be fixed for moderate expense but like the others suggested a superior replacement is the go if you are going to keep the machine. My Mazda Bravo sprung a top tank leak some years back........put in an after market TWIN core all metal unit (brass I think)..........your radiator specialist will know all about them (can't recall the brand now). I got old fashioned performance and reliability, with improved cooling capacity. Might be $400-$500 when its all over but it'll be the last radiator you put in I'd guess.

I had the same problem on my 80 , sent the raidiator out for a full rebuild and new top tank. Havent had any more leaks for 100,000 kms