When the fluid in the expansion tank reaches the COLD mark, start the engine.
If the overload warning continues, there is one more thing you can try. You can add coolant directly to the radiator, but be sure the cooling system is cool before doing this.
Warning: Steam and boiling liquid can seriously burn you. They are under pressure and can escape under high pressure if you remove the radiator cap. Do not open the radiator cap until the system has cooled.
1. You can remove the radiator high pressure cap when the cooling system including the radiator cap and radiator hose cools down. Turn the radiator cap slowly counterclockwise to the first mark. Do not press down the radiator cap. If you hear a hissing sound, wait until it stops.
2. Then turn the lid further, but press it down. Remove the lid.
3. Fill the radiator with 50/50 DEX-COOL coolant mixture to the base of the filler neck.
4. Then fill the tank up to the COLD mark.
5. Close the reservoir cap, but do not close the radiator.
6. Start the engine, wait until the upper radiator hose warms up. Observe the engine fan.
7. At this time, the coolant level inside the radiator may decrease. If the level has decreased, add coolant through the filler neck until the level rises to the base of the filler neck.
8. Then screw the radiator cap back into place. At any time during this procedure, if fluid leaks from under the cap, open and close the radiator again. Make sure the arrows on the radiator cap are positioned as shown in the picture.
(The article is based on data from the website «chevyman.ru»)