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Q: Swollen coolant water pump bypass hose

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I have a coolant hose that I need help identifying. It comes from the bottom of the thermostat and appears to go into the block. The problem I have is the hose swole enough to strike a bolt close by and puncture it. I haven't had any cooling issues lately, but I did recently "fix" a leak I couldn't find by using some sort of cooling system stop leak.

My car has 150000 miles.
My car has an automatic transmission.

A: The small hose that comes from the bottom o...

The small hose that comes from the bottom of the thermostat housing and has a small bend then goes straight down into the top of the water pump is called the water pump bypass hose. This is the hose you wanted to be identified. If you had a coolant leak and it stopped when you used the stop leak is most likely coming from the thermostat housing. The thermostat housing is made from plastic with rubber O-rings to seal in the coolant. The housings are known to crack and start leaking coolant. You would need to replace the thermostat housing assembly to stop the leak.

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