On my 87 Toyota truck the coolant goes into the overflow tank and I have to add coolant ,why doesn't it return?

the over flow is designed for expansion and contraction of the coolant supply. If you have to keep adding coolant there either is a leak or the engine is consuming it as in a blown headgasket; two fairly common issues especially on 22R. Some checking and testing will be needed to find the cause, but on an 87 it probably has high miles as most do by now and they all eventually will need a gasket replaced. Get it checked as letting it go can cause more damage. If it ends up needing major surgery then you have to decide what is best-to invest in repairs or sell and get something else. Good Luck--T&T

The coolant reservoir has an overflow tube that drains under the truck. Have you seen any small puddles of coolant under the truck, usually after you shut off the engine after its well warmed-up? If so, the coolant system is just bleeding off the excess coolant.

You mentioned it despatched all of the coolant to the reservoir. Did your motor vehicle overheat returned? If confident then you certainly maximum possibly have a blown head gasket or a cracked head. you will possibly be fortunate & in undemanding terms have a caught thermostat or plugged radiator. Have a good save examine each thing out.

Replace radiator cap,there is check valve on it to let coolant return to radiator when there is suction.

sounds like you need a new radiator cap