Testing for Cooling System Air Leaks

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Testing for Cooling System Air Leaks

With the engine cold (off overnight)
Remove overflow tank cap to equalize pressure
Replace cap
Start engine, let idle for about 30 seconds
Turn engine off
Remove overflow tank cap and listen for escaping pressure

If any pressure builds up during this brief time, there is a leak between the combustion part of the engine and the cooling system. There are many possible causes, including cracked head, cracked block, and head gasket failure.
Dave B.
www.BlueHummer.com

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