Water shooting out of radiator hose when I pull radiator cap off.

Asked by May 03, 2017 at 06:12 PM about the 2005 Pontiac Grand Prix Base

Question type: Maintenance & Repair

I was sitting in traffic and noticed my car started to
overheat. So I pulled into a 7/11 and popped my
hood. Nothing smelled bad or burned. So I went to
pull my radiator cap off and POW. a jet of water
came shooting out of it. Does this mean I have a
cracked head or blown head gasket? Thanks

3 Answers


No, the cooling system builds up pressure when the engine gets to operating temperature. The cooling system was just under pressure when you removed the radiator cap, pushing the expanded coolant out. Never a good idea to remove the radiator cap when the engine is hot. When you have too remove a radiator cap you should have some leather gloves on or a towel over the cap and remove it slowly. When an engine is starting to over heat you do want to get the cap off with the engine running. Once the cap is off then fill the radiator up with the engine running to cool it down.

1 of 1 people found this helpful.

Ah that makes sense. Thank you very much!


Not only is the coolant under pressure but the water may be super heated. If you remove the cap, the super heated water instantly becomes steam which can peal your skin off! Super dangerous!

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