Hi guys,i have 3 small holes in my radiator tank and was wondering how effective fibre glass is with heat to repair it or do you maybe know of any other method to repair it.It's useless to buy another radiator for N$ 3000.00 if i can repair it for N$ 100.00

 

No.. not fibreglas.
Plastic or metal tanks?
Are these holes or cracks? If they are cracks drill very small holes at end of crack to stop them

Metal - Solder or a high heat 2 part epoxy such as sold in north America as "J-B Weld"

Plastic - hole: find brass or stainless fine thread screw, drill a hole small than screw. prep area make it clean, coat hole and screw with ABS cement and force-thread it into hole.
Crack - find scrap piece plastic rad tank or similar hi temp plastic to conform to area. clean well/sandpaper both tank and patch. drill small holes to attach patch to tank and coat both tank and patch with abs cement as above.
...or... rough area and try the 'J-B Weld' type epoxy.

Except for the solder fix, allow 4 hours for epoxy, 24 hours for abs