Question: Will a radiator stop leak additive really stop
a coolant leak?
Answer: Yes, but only if the leak is in a component that
normally responds to such a product.
Leaks that can often be sealed with an additive include radiator
and heater core pinholes (but not cracks), seepage leaks around
engine freeze plugs, thermostat, manifold and head gaskets, and
porosity leaks in aluminum heads or blocks.
Leaks that do not usually respond to additives include leaks in
hoses, the water pump (around the shaft), or the radiator cap.
Large cracks, cracks along outside corners or where hoses attach
to the end tanks on the radiator are also very difficult to seal.
Even if a leak is sealed by an additive, no manufacturer will
guarantee that such a seal will last. Repairing or replacing
the leaky component, therefore, is the best cure -- and the only
one that will guarantee lasting results.
