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gomi_otaku
gomi_otaku, VW Technician
Category: VW
Satisfied Customers: 3379
Experience:  VW FastTrack '00-'01, VW Academy Chicago and Seattle '00-present, VW Certified
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Car is overheating coolant level is good changed the sensor

Customer Question

car is overheating coolant level is good changed the sensor is it the water pump or thermostat how do i know if the radiator is clogged
Submitted: 1 year ago.
Category: VW
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  gomi_otaku replied 1 year ago.

Turn your A/C switch on, and see if the electric fans run. It's common for them to fail, since the control module is built into the left side fan assembly.

Customer: replied 1 year ago.
the fans do run they even run after i shut it off
Expert:  gomi_otaku replied 1 year ago.

You should be able to run the engine to temp, if the thermostat is opening the upper hose will get hot while the lower hose stays cold, when the thermostat opens then the lower hose will get warmer as the hot coolant going into the radiator is cooled (slightly) by the fans running, and is slightly cooler going back to the engine than what is coming out. You can check it with your hands, but it's best to have one of those handheld laser thermometers (they sell them at Home Depot, Sears, etc)

Customer: replied 1 year ago.
what about the thermostat or water pump
Expert:  gomi_otaku replied 1 year ago.

This is how you test those two things- if the water pump is not pumping, then the hot coolant will never get to the radiator, it will just sit in the engine and eventually boil over. If the thermostat is not opening, then the coolant will be circulated (and you will get heat in the interior, which you typically would not if the coolant pump is not working) but the lower hose will stay cold no matter how hot the engine gets.

Customer: replied 1 year ago.
oh ok the heat di dcome on i will check the lower hose so it should be cooler then the top ?
Expert:  gomi_otaku replied 1 year ago.

They will both be cool if the engine has not been running- but yes, the lower hose should be cooler than the top at all times.

Expert:  gomi_otaku replied 1 year ago.

If the thermostat is opening, it should at least be warm.

Keep in mind that any leak in the system will not allow it to build pressure, and the coolant will "boil" and the engine will overheat. So if your coolant cap is loose, or you have any leaks in the seals or hoses, that could be your issue.

Customer: replied 1 year ago.
cap is good and the coolant level is good when i changed the ect i did lose some coolant
Customer: replied 1 year ago.
the lower hose is cooler then the the top
Expert:  gomi_otaku replied 1 year ago.

Does the coolant actually boil over, or is it just the coolant temp gauge on the cluster showing it is overheating?

Customer: replied 1 year ago.
just the gauge
Customer: replied 1 year ago.
there is no coolant lose
Customer: replied 1 year ago.
if i try to open the fill bottle a lot of coolant rushes in
Expert:  gomi_otaku replied 1 year ago.

Which coolant temp sensor did you replace? Where is it located?

Customer: replied 1 year ago.
driver side near top
Expert:  gomi_otaku replied 1 year ago.

There is another Engine Coolant Temp sensor in the lower radiator hose, right by the radiator. I would replace that one as well, the two sensors work in conjunction. Also, check the connectors on BOTH sensors to make sure there is no sign of coolant migration or corrosion on the pins. If you still have the same issue, then I would suspect the thermostat, though if that is the case you should have a check engine light on or at least stored faults.

You can often have faults read for FREE at large auto parts stores like Autozone

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