How can you insure that the car's radiator is full when it don't have a cap just the plastic filler tank

Please follow the below instructions to cool down the overheat.

1 Turn off the engine.
2 Wait. If the engine is steaming, don't open the hood.
3 Pull the hood release lever under the dashboard to open the hood when the car has cooled completely.
4 Walk around the front of the car, reach under the hood, find the latch and squeeze it. As you squeeze the latch, pull up and open the hood.
5 Check the coolant reservoir tank first. It's a plastic jug that has a small hose running to the radiator. The reservoir can be filled when the engine is hot (except on German and Swedish cars, the plastic reservoir is also under pressure, so don't open when the engine is hot).
6 Open the radiator cap with a rag. Remember: open it only after the engine has completely cooled. If you're not sure, don't open the cap. If you open the cap while it's still warm, you may burn yourself with steam or hot coolant. Open the cap slowly, as if you were opening a bottle of soda that has been shaken up.
7 Examine the radiator. Look inside and see if there's coolant left. If needed, fill to the top of the radiator.
8 Put the radiator cap back on.
9 Check to see that the upper or lower radiator hose, or any of the heater hoses, hasn't burst.
10 Restart the engine.
11 Watch the temperature gauge obsessively. Don't let the needle go into the red. Turn off the engine if the gauge approaches the red zone.
12 Understand that you can continue driving a high-temperature vehicle if you're far from a phone or a service station and the car does not need coolant (or does not respond to these instructions). However, drive only as long as you stop and turn off the engine whenever the gauge gets close to the red, and let the engine cool down until you drive again. This may take a long time, but it probably beats walking.
THanks.

Let the vehicle cool off completely, then remove the radiator/surge tank cap and fill it to the indicated full level. Leaving the cap off, start the engine and allow it to run until the temp gauge reaches normal, about 10 to 15 minutes. Place the heater on high, observe to see that you have good interior heat, and top off the radiator/surge tank. Reinstall the cap and drive it, observing the temp gauge. If it is still not right, stop and squeeze the top radiator hose-it should be difficult, if not impossible to calopse, and hot. If it is easy to calopse, you have an internal, or external leak, or your cap is not holding pressure.

I assume you have a 3.8L V6. Probably thermostat, but first take a look in the radiator to make sure it is full. Not just the plastic overflow tank, take the radiator cap off and look. Make sure the engine is cold though. The radiator should be full to the top. The way the system works is that as you drive your car, the water heats up and expands and the check valve in the radiator cap will let the overflow go into the plastic tank when the pressure get over a set amount usually 14-17 lbs. When you shut off your engine, the water will be slowly sucked back into the radiator as the engine cools. if the radiator cap is bad, it may not let the water get sucked back into the radiator and the engine will run hot, you will get air and steam bubbles in the engine, the thermostat will work as long as it has water running by it but if a slug of steam goes by it, it will close. "Burping" that engine is a pain but just keep the overflow tank full and check it every time you *start* the car. The air will work itself out.

Hello, If your car overheats and damages the engine, you have no one to blame but yourself. Keep your eyes on the temperature gauge and never let the needle move into the red. Pull over before it gets too hot. And to resolve this follow this steps:

1. Turn off the engine.

2. Wait. If the engine is steaming, don't open the hood.

3. Pull the hood release lever under the dashboard to open the hood when the car has cooled completely.

4. Walk around the front of the car, reach under the hood, find the latch and squeeze it. As you squeeze the latch, pull up and open the hood.

5. Check the coolant reservoir tank first. It's a plastic jug that has a small hose running to the radiator. The reservoir can be filled when the engine is hot (except on German and Swedish cars, the plastic reservoir is also under pressure, so don't open when the engine is hot).

6. Open the radiator cap with a rag. Remember: open it only after the engine has completely cooled. If you're not sure, don't open the cap. If you open the cap while it's still warm, you may burn yourself with steam or hot coolant. Open the cap slowly, as if you were opening a bottle of soda that has been shaken up.

7. Examine the radiator. Look inside and see if there's coolant left. If needed, fill to the top of the radiator.

8. Put the radiator cap back on.


9. Check to see that the upper or lower radiator hose, or any of the heater hoses, hasn't burst.

10. Restart the engine.

11. Watch the temperature gauge obsessively. Don't let the needle go into the red. Turn off the engine if the gauge approaches the red zone.
Thanks

Do you have an overflow tank that has low level in it?
LEVEL CHECK The coolant level should be checked regularly. Serious engine damage can occur if the engine overheats. CAUTION
Check the coolant level when the engine is cold; serious injury could result from escaping steam or hot fluid if checked when hot. If your car is equipped with an electric cooling fan, make sure that the ignition switch is OFF. The cooling fan will automatically operate if the ignition switch is on and the engine coolant temperature is high, or if the wiring connector on the thermostat housing is disconnected.

1. Depress the button on the thermal expansion tank (coolant recovery reservoir) safety cap, if there is one. Allow all of the pressure trapped in the system to escape. CAUTION
   The radiator is not factory-equipped with a safety cap. Do not remove the radiator cap before removing the expansion tank cap, or when the engine is hot. Fig. 1: Remove insects and debris from the radiator fins
   
   
2. Remove the expansion tank cap. The expansion tank should be 1⁄3 full, unless Full and Low marks are provided. The level should be well above the bottom of the tank when the engine is cold.
3. If it is not, carefully remove the cap from the radiator. The radiator should be full.
4. Add a 50/50 solution of ethylene glycol (or other suitable coolant) and clean water. If there was no coolant in the expansion tank, fill the radiator until the level is near the inlet port and install the radiator cap. Then, fill the expansion tank to the specified level, and secure the expansion tank cap. When checking the coolant level, the pressure cap should be examined for signs of age or deterioration. Check it for a worn or cracked gasket. If the cap doesn't seal properly, fluid will be lost and the engine will overheat. A worn cap should be replaced with a new one. The fan belt and other drive belts should be inspected and adjusted to the proper tension. (Please refer to the belt inspection and adjusting procedures, earlier in this section.) Remove the radiator cap and run the tip of your finger around the inside of the filler neck. Check for excessive deposits of rust or scale around the filler neck lip and the filler port. Make sure the coolant is free of oil. Replace the coolant as necessary. Hose clamps should be tightened, and soft or cracked hoses replaced. Damp spots, or accumulations of rust or dye near hoses, the water pump or other areas indicate possible leakage, which must be corrected before filling the system with fresh coolant. Periodically clean any debris, leaves, paper, insects, etc. from the radiator fins. Pick the large pieces off by hand. The smaller pieces can be washed away with water pressure from a hose. Carefully straighten any bent radiator fins with a pair of needle nose pliers. Be careful as the fins are very soft. Don't wiggle the fins back and forth too much. Straighten them once and try not to move them again.
   

Does your engine overheat? Could be a thermostat that is stuck, let me know with some clarification and i can help ou better. Thanks

normaly you add to the plastic res , but lets make sure its full , so when it is cold the engine then open the radiator cap the metal one slowly and first top it off then close cap all the way and fill plastic res to the cold fill line. but usualy you just make sure the plastic tank is either full to the hot line or cold line , which is when the engine is hot or cold. but it is also good to check both .

The water (coolant) in the expansion tank will rise and fall with the engine temperature. What the expansion tank does is collect and return coolant to and from the engine. When the engine warms up the coolant gets hot, builds up pressure and opens up the radiator cap. The coolant then goes into the expansion tank. Now when the engine cools down the pressure drops in the cooling system and the pressure drop (vacuum) pulls the coolant back into the engine via the radiator cap. The radiator cap allows the cooling system to build up pressure and by doing so increases the boiling point of the coolant, but when that pressure exceeds the caps rating the cap opens and the coolant goes to the expansion valve. The cap has another part to it that when the engine cools down and a partial vacuum is created in the cooling system a "valve" in the radiator cap opens and allows the coolant to be drawn back into the engine. I would look at your radiator cap to see if any gunk or build up is on it, and check the rubber gaskets for cracks. It's easiest just to replace the cap because they are inexpensive and easy to replace (2-10 dollars). The expansion tank should have two hoses on it. The one on the bottom comes from the radiator and the one on the top (possibly part of filler cap) runs down and is open to the ground. That way if it is overfilled or becomes overfilled it will slowly leak onto the ground. When and if you change your radiator cap, make sure the engine is cooled down, remove cap and start engine and turn heater to full blast, full heat. Leave the cap off and let it run until engine warmed up. This should burp out any air pockets that may have happened when coolant was changed. Also top off the coolant in the radiator while it is running. Hope this helps and good luck