Re: Strange water flow problem 288 cu in engine

Posted by HH56 On 2022/8/15 10:08:18

Trapped air means that for some reason liquid was not able to flow in and completely fill an area inside the engine or radiator that normally would contain coolant. The space that should have coolant flowing thru was full of air that could not be expelled so it is trapped.

This is not generally an issue on that engine however it conceivably could happen if the car was parked in such a way when it was filled that the rear of the engine was at a higher level than the front. If the rear of the engine is high liquid would find it easier to just stay toward the front of the engine and never reach the back thus trapping air.

If your car is parked on level ground the front of the engine is normally tipped up a very small amount. As coolant enters the radiator it wants to flow down to the bottom and out the bottom hose into the water pump return thus entering and filling the engine sort of from bottom to top, rear to front and pushing any air ahead of it up into the head and then out the upper hose. There should be enough leakage even thru a closed thermostat air is pushed out until the entire cooling system is filled. Air could still be in small higher up places but once the engine is started the pump and coolant flow will push coolant into any tiny spots left over such as the heater hoses and core which would hold around a quart.

Unless you have a leaking head gasket and that is the cause of the large bubble, chances are the bubble that came out got rid of most of the trapped air. You might make sure the car is on level ground and then try filling a bit more just to be thorough.

The normal maximum coolant level is you should be able to look in the radiator cap hole and see the top of the coolant at about 1 inch below the flat sealing surface at the bottom of the fill opening just below the overflow outlet That inch allows enough space for expansion so the coolant is not forced out the cap and into the overflow tube when the engine gets hot.