what causes overflow in radiator

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05-08-2010, 12:37 PM

#16

dyte2004

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Year: 1994

Model: Cherokee

Engine: 4000cc

rad cap change it with a good quality one

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05-08-2010, 01:21 PM

#17

cokeicee

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Year: 1992

Model: Cherokee

Engine: 4.0L

Quote:

Originally Posted by dyte2004

rad cap change it with a good quality one

hehe went out and got one today

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05-09-2010, 05:13 AM

#18

96tudor

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Location: Greenville, SC

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Year: 1996 two-door SE

Model: Cherokee

Engine: 4.0

Quote:

Originally Posted by cokeicee

Your right about the open cooling system but the expansion tank has a line that goes from the bottom of the expansion tank to the radiator. So when the engine cools it sucks coolant from the expansion tank to radiator and when it heats up it goes into the expansion tank.

Maybe thats it when my engine is off the line is in between the fill and full line. But how do I know if the thermostat is completely open or not while the engine is on?

I looked at my '96, and I saw that part of the line connecting the radiator to the reservoir is molded into the reservoir running to the bottom instead of the hose attaching to the bottom of the reservoir. And you're right, that line is a two way street.

When you're driving the vehicle, you know that the thermostat is open with the engine running because it's not overheating.

When you're refilling the cooling system, you'll know that the thermostat is open because the upper radiator hose will be very hot, the coolant in the radiator is hot, and the coolant level in the radiator (looking into the neck) will go down. (The neck on these radiators don't allow you to actually see coolant flowing through the radiator.) Remember that when the relatively cool water (coolant) from the radiator enters the engine after the thermostat initially opens, the thermostat will begin to close down again. Make sure the coolant cycles through the system twice before installing the cap. You can also stick a thermometer into the neck to determine if the coolant has reached operating temperature.