Chemiweld is a cheap way out and should be used in emergancys only. And dont just dump it in. Read the instructions and do it properly or else you will start to block things up.
Find the leak first. If its a pin hole in a hose or a cracked rad its not going to help. Just replace the offending part.

I have seen it used to stop leaks on a VS 5ltr on the water pump and both heads/vally cover. It worked for a couple of months then starting leaving small puddles.

Would you rather trust a bunch of metel flakes in a can or a brand new part when your out in the middle of nowhere in 40deg heat?