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Category: Nissan
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Experience:  ASE certified tech ADVANCED LEVEL PERFORMANCE. Wisconsin certified emissions state inspector
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nissan sentra 2003 1.8l coolang not circulating throw heater

Customer Question

nissan sentra 2003 1.8l
coolang not circulating throw heater core. Both hoses stay cold.
new radiator & thermostat.
Top radiator hose get hot and bottom relatively cold.
Disconnected top heater core hose from thermostat bloc and no coolant going out event with engine running while warm
Submitted: 6 years ago.
Category: Nissan
Expert:  AMEDEE replied 6 years ago.

Your coolant may be low, or there is an air pocket in your cooling system causing a low or not heat situation. You will have to bleed the system. With the engine cold take off the radiator cap and start the motor. as the engine warms up, keep the coolant topped off. the cap should be the highest point int cooling system. If not there will be a bleeder screw that you can open to let out air. Here is a hint, Turn on the heat when the engine is warm, if it is blowing cold, than there is a huge air pocket and the system.

Also, try to raise the front of the vehicle up in the air and run the engine at about 2000 RPM, and see if the heater starts working. Feel the lower radiator hose to see if it opens and allows coolant to flow from the radiator. Make sure that the engine does not overheat while doing this procedure.
If the system works normally after having the front of the vehicle up in the air and then acts up again while driving, the system may be getting more air introduced to the system, and may need the head rechecked for cracks.
AMEDEE and 5 other Nissan Specialists are ready to help you
Customer: replied 6 years ago.

I hop it is only the head gasket, may be cracked cylinder head.

I made your suggestions and I keep getting bubbling from the radiator openning and if i increase rpm over 2000 I get a small blast from the radiator. Never got heat from heater.


Thank you for your help

Expert:  AMEDEE replied 6 years ago.



THanks for the accept!


If you keep getting air from the cooling system bubbling up, either there is one big air pocket or the head gasket is bad. I would try to bleed the engine a few times before checking for a blown head gasket.


Good luck with everything!


Let me know if you have any further questions!

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