I've had my upper tank soldered a number of times, and each time it was a diminishing return -- arguing with the shop because they didn't want to do it, arguing with the shop when they claimed my coolant was all brown and rusty and I'd been neglecting my cooling system (when I had changed the coolant not 2 weeks before), etc. The last attempt at soldering the tank seam lasted about 1.5 years, but the upper tank seam had been leaking for the last few months with a crack in the solder that was visibly lengthening. I decided to install a new CSF radiator last weekend. So far it seems to be working well.

So... all that to say that in my experience radiator tanks (at least) can be soldered, but it isn't necessarily a permanent repair.

I've no personal experience with electric fans in a Montero, but common sense would seem to say the polarity for your fan motor is reversed <img src="/forums/images/graemlins/cyclops.gif" alt="" />

Eric W.