Radiator water level
Thread Starter
3rd Gear
Joined: May 2025
Posts: 3
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Radiator water level
I have 2001 base hatchback, I fill the radiator header tank, drive around and not overheating but when I stop and come back to the car there is water on the ground, am I over filling the header tank, on a positive note car goes great and is very economical on highway driving, I am a LS1 convert
Race Director
Joined: Oct 2004
Posts: 12,864
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You have hot and cold level marks on the expansion tank. Where is the coolant level in relation to those marks? If you overfill it, when it gets up to temp, it has to expand somewhere. If that checks out, early C5s had a cap rated@15lbs. Later ones had an 18lb rated cap. I never has a leak with the 15lb cap. BUT-I DID have a slow leak due to one of the OEM spring type hose clamps losing some of its tension after 20 years. It was one of the heater hoses right at the water pump/T-stat area. It was so slow, it never dripped to the pavement, due to the 200° water pump evaporating it before it could pool up. Pressure test your coolant system. That will find the problem.......
