rust problem
Bro,
I kena the same thing before. What you can do.
Get the Nasa Brand radiator flush. run it for a while then flush kow kow. after flush use battery water (the not acid type, i think it's something like air suling, reason coz your block is made of cast iron, when tend to rust if you don't run the engine for some time. reason why use this water is because it does not have salt in the water) you'll need a few bottle's lar. i think around 4 or 5. then also add coolent into the system. try the toyota coolant (some swear by it) it's red in color and apparently quite good.
this is what i did and so far no problems.