Toyota Repair: Breaks 93 4 Runner, pin holes, raditor

Question
I have a '93 4 Runner four wheel drive. Sometimes while breaking experance a spongy feeling in the break petal. The petal will drop a few inches before it catches. The bread fluid has never been low so I can't beleve their is air in the line. In addition the tank on the raditor showes a some water deposits and looks like pin holes existed and are pluged. Is this a concern? Thanks for your help.

Answer
The first thing you need to do is check the brake pads and the rear brake shoes for wear, if they are good, a rear brake adjustment may be all that is needed, if they go far out of adjustment the brake pedal can feel low and spongy.
On the second question, I think it's time to replace the radiator.