Coolant overflow not being used
Thread Starter
Safety Car
Joined: Mar 2005
Posts: 4,723
Likes: 11
From: Winnipeg Manitoba, Canada
Coolant overflow not being used
I've read my fsm several times and can't understand why my overflow isn't being used. To my understanding once the car reaches operating temperature coolant is supposed to be sent to the overflow where the level would reach hot. After the car cools down the coolant is sucked back into the rad. My coolant isn't doing this. I know the system is full, there aren't any leaks and I have a brand new rad cap. After I drive the car I check the overflow but its always at the same cold level. The coolant isnt hot or anthing, but somtimes there is steam coming from the tank. The car does not overheat either. Any ideas? Thanks 
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The cooling system in your car should automatically pull the coolant into the radiator as the engine cools.
You possibly have a faulty or incorrect radiator cap or you may have a small leak somewhere in the cooling system allowing air back into the cooling system as the engine cools off.
The cooling system must be air-tight in order to pull the coolant out of the overflow reservoir.
As the engine heats up, the coolant inside it expands. Without the expansion tank, the coolant would flow out of the overflow tube and be lost from the cooling system onto the street. Instead, the coolant flows into the expansion tank.
Since a vacuum is created in the cooling system when the engine cools, the vacuum causes some of the coolant in the expansion tube to be sucked back into the system.
Because a cooling system with an expansion tank is virtually a closed system, the coolant can flow between the system and the expansion tank as it expands and contracts. This way, no coolant is lost if the system is functioning properly.
Another function of the expansion tank is to remove air bubbles from the cooling system. Coolant without air-bubbles is much more efficient than coolant with air bubbles, because it absorbs heat much faster.
The advantage of the expansion tank is that while the level of coolant contained in it rises and falls, the radiator is always full.
You possibly have a faulty or incorrect radiator cap or you may have a small leak somewhere in the cooling system allowing air back into the cooling system as the engine cools off.
The cooling system must be air-tight in order to pull the coolant out of the overflow reservoir.
As the engine heats up, the coolant inside it expands. Without the expansion tank, the coolant would flow out of the overflow tube and be lost from the cooling system onto the street. Instead, the coolant flows into the expansion tank.
Since a vacuum is created in the cooling system when the engine cools, the vacuum causes some of the coolant in the expansion tube to be sucked back into the system.
Because a cooling system with an expansion tank is virtually a closed system, the coolant can flow between the system and the expansion tank as it expands and contracts. This way, no coolant is lost if the system is functioning properly.
Another function of the expansion tank is to remove air bubbles from the cooling system. Coolant without air-bubbles is much more efficient than coolant with air bubbles, because it absorbs heat much faster.
The advantage of the expansion tank is that while the level of coolant contained in it rises and falls, the radiator is always full.
Thread Starter
Safety Car
Joined: Mar 2005
Posts: 4,723
Likes: 11
From: Winnipeg Manitoba, Canada
Originally Posted by CFI-EFI
I suspect that your cooling system isn't as full as you think it is. You might confirm, also that you bought the correct cap.
RACE ON!!!
RACE ON!!!
Thread Starter
Safety Car
Joined: Mar 2005
Posts: 4,723
Likes: 11
From: Winnipeg Manitoba, Canada
Originally Posted by onedef92
The cooling system in your car should automatically pull the coolant into the radiator as the engine cools.
You possibly have a faulty or incorrect radiator cap or you may have a small leak somewhere in the cooling system allowing air back into the cooling system as the engine cools off.
The cooling system must be air-tight in order to pull the coolant out of the overflow reservoir.
As the engine heats up, the coolant inside it expands. Without the expansion tank, the coolant would flow out of the overflow tube and be lost from the cooling system onto the street. Instead, the coolant flows into the expansion tank.
Since a vacuum is created in the cooling system when the engine cools, the vacuum causes some of the coolant in the expansion tube to be sucked back into the system.
Because a cooling system with an expansion tank is virtually a closed system, the coolant can flow between the system and the expansion tank as it expands and contracts. This way, no coolant is lost if the system is functioning properly.
Another function of the expansion tank is to remove air bubbles from the cooling system. Coolant without air-bubbles is much more efficient than coolant with air bubbles, because it absorbs heat much faster.
The advantage of the expansion tank is that while the level of coolant contained in it rises and falls, the radiator is always full.
You possibly have a faulty or incorrect radiator cap or you may have a small leak somewhere in the cooling system allowing air back into the cooling system as the engine cools off.
The cooling system must be air-tight in order to pull the coolant out of the overflow reservoir.
As the engine heats up, the coolant inside it expands. Without the expansion tank, the coolant would flow out of the overflow tube and be lost from the cooling system onto the street. Instead, the coolant flows into the expansion tank.
Since a vacuum is created in the cooling system when the engine cools, the vacuum causes some of the coolant in the expansion tube to be sucked back into the system.
Because a cooling system with an expansion tank is virtually a closed system, the coolant can flow between the system and the expansion tank as it expands and contracts. This way, no coolant is lost if the system is functioning properly.
Another function of the expansion tank is to remove air bubbles from the cooling system. Coolant without air-bubbles is much more efficient than coolant with air bubbles, because it absorbs heat much faster.
The advantage of the expansion tank is that while the level of coolant contained in it rises and falls, the radiator is always full.
Team Owner
Joined: May 2006
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From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
If you look closely at the Cap when you remove it from the tank you'll see that the line that goes to the over flow tank is above the lower line, when it get's hot then the spring will release the pressure into the over flow tank. Then it will suck the cool fluid back in when it is ready!
Hope this helps!
Thanks,Matt
Hope this helps!
Thanks,Matt
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