Skip the auto shop - Our mechanics make house calls

Q: Swollen coolant water pump bypass hose

asked by on

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.

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.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Best water pump or "good enough"? 2004 Porsche Boxster S

Hi - there is a certain value from the buyers point of view in being to able say you "only used OEM parts" - and I don't mean necessarily ones that came in a Porsche box. Pierburg is an OEM...

Q: Number #1 cylinder misfire?

Hi there. As you already know, replacing components without proper diagnoses can expensive and time consuming without resolution. Assuming, the engine is mechanically sound, good cylinder compression and valve train properly opening and closing, circuit tests need to be performed....

Q: Gurgling noise and transmission fluid leak 2009 Chevrolet Malibu

Hello - the gurgling noise is most likely a cooling system issue - perhaps overheating that has not yet caused a failure. Check coolant level (engine cold), and the transmission fluid level as well. Look for clear, pinkish (not dark)...

Related articles

What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.