Excessive water pressure in radiator causing overflow tank to overflow in 1997 7.3 powerstroke

stuck thermostat
cooling fan motor slow to cool
hoses too soft or leaks at clamps
clogged radiator
head gasket blown

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Yes, it is important to include the overflow tank or bottle as integral with the radiator and coolant system as a whole. They all intermix. Actually, the level in the overflow tank is a true measure of the correct amount to keep your coolant at. There are two marks on the overflow: full hot and full cold. The coolant system on all modern cars is a sealed system and therefore should never require adding, save a very small amount through evaporation within the overflow tank- the only part that is open to atmosphere.

So once you get all the air out of the system that is possible, both in the engine and in the radiator, you have a full level everywhere, including the overflow tank where it should always remain somewhere between the full hot and full cold marks.

You are right that the overflow collects the heated radiator coolant. But it is due to the expansive properties of coolant-or water- that it expands when heated, (but not boiling-that is very bad news of a different sort). Your radiator cap is designed to open at a specific pressure, just enough to allow coolant to flow into the overflow. As the engine and coolant cools, it contracts, the level drops in the radiator, and a natural vacuum there will siphon the overflow tank back into the radiator until it is full again. That is why you have the full hot and full cold marks.
I will shut off the lecture now. I hope you have liked my answer. If not, I give you permission to kill me now- if I may so jest.

If the engine overheats from a thermostat
stuck closed or bad head gasket

Pressure testing just tests that the radiator cap resists a certain amount of positive pressure. I assume you are saying that it is not drawing back from the overflow when the engine cools down. It is likely that the coolant is being blocked right inside the overflow jug by some dirt or debris. Remove the overflow jug and clean it out - and clean the overflow hose too, in case it is obstructed.

It's probably the radiator overflow tank hose. It is supposed to be connected the the coolant overflow tank and also the other end at the radiator, next to the pressure cap. It allows excess coolant to escape the radiator if necessary and also to **** in coolant if needed.

A tank used for storing excess coolant; connected to the cooling system with a small-diameter overflow hose.

The coolant reservoir is the bottle,under the hood, that holds the radiator fluid. it is also known as a overflow bottle. When the car gets hot,the overflow bottle, releases steam to relive the pressure in the radiator. excess coolant is also stored here.




I hope this helps, Mike from fixya.

Until you get it figured out use regular water. Replace thermostat and radiator/coolant tank caps. Thermostat regulates pressure in the motor and allows radiator to cool. Caps regulate atmosperic pressure. Either or both being bad will cause you system to siphon and fail.

When you top off the radiator you fill it to the neck where the cap goes. When the engine heats up the antifreeze eventually will distribute and the excess will go into the overflow bottle.

After the car cools, it will draw the antifreeze from the overflow tank into the radiator. Then check the level line on the overflow bottle(tank) for the normal amount of antifreeze per marks on the bottle.

You should have your radiator cap checked for its pressure rating. Use the type of cap which allows for an overflow system. The older caps would not let the antifreeze flow both ways.

Have you changed the water pump ?

Due to the complexity of the newer cars on the raod today!! what you are experiencing is Normal!!! since the coolant systems on the newer cars run at such a higher pressure and a high Rpm the reserve tank which has it's on drain hose for excessive overflow from the radiator allows the extra high pressure release from the radiator to back flow to the reserve tank and then out the reserve tank overflow hose on to the raod