I drive a 1997 Plymouth Breeze. The fluid in the engine coolant tank boils sometimes. Why?

Question

1997 Plymouth Breeze, why does the fluid in the Engine Coolant tank boil occasionally? It doesn't happen every time, but it has been happening off and on for a couple of years now. There is no smoke, the engine doesn't overheat and there is no other sign of stress. What is happening?

Answer 1

It's probably not boiling. It's the coolant escaping the system as it expands and going into the coolant tank. It looks like it's boiling as it enters the tank from the radiator. When the engine cools down and the coolant shrinks, it draws the coolant from the tank back into the radiator. It's all normal.

Answer 2

It could be a head gasket, or thermostat, Or there may be air bubbles trapped in your cooling system. There should be a bleeder screw on the thermostat assy. Just follow the top radiator hose to the thermostat housing and look for a small bolt sticking out of it. Crack this bolt loose a couple of turns. if nothing comes out that's the air bleeding out or the bleeder could be clogged. If it is clogged then back it out almost all the way but not completely out and see if air or bubbles will come out near the threads. Do this with the car running at idle. Eventually you should see nothing but coolant coming out. Then tighten up the nut and top off your coolant. If you can't get rid off the air and it doesn't fix the problem get it checked for a blown head gasket. They do have a tool that uses a special fluid that will change color if the head gasket is blown.

Answer 3

When the the engine heats up it also pressurize. Pressurized water has a higher boiling point so it sounds like the rubber on your radiator cap is old and not letting it pressurize sometimes.

Answer 4

Replace the thermostat or you will be replacing the engine.

I am guessing your temperature light or dial is not working also.

It should be beyond 200 degree if it is boiling