We have a 2002 Honda Civic , 1.7L Engine.. Cruising at Highway Speeds the Heater Blows Satisfactory Heat, come to a Stop Light Idling for a couple minutes the Heater starts to Blow Luc Warm Air.. Question? Could that be the Thermostat not working properly??

Most likely, the problem is with the heater core. Try reverse flushing the heater core, to remove any corrosion, and refilling with a 50/50 mixture of the proper antifreeze and distilled water. If you want, install a genuine Honda thermostat after you drain the system.

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Originally Posted by TxGreaseMonkey

Most likely, the problem is with the heater core. Try reverse flushing the heater core, to remove any corrosion, and refilling with a 50/50 mixture of the proper antifreeze and distilled water. If you want, install a genuine Honda thermostat after you drain the system.

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As I Described Satisfactory Heat while Cruising , Becoming Lukewarm after a couple minutes @ Idling Speeds.. Was told because the Water Pump has Slowed Down could be a contributing factor ?? Thoughts Appreciated Thanks...

A 13 year old vehicle can have many issues to address, but I go with TXGM on this heat issue. It's an easy thing to backflush your own heater core and get you through the winter.

If the water pump were faulty then the car engine would overheat due to lack of coolant circulation.

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Originally Posted by talaniman

A 13 year old vehicle can have many issues to address, but I go with TXGM on this heat issue. It's an easy thing to backflush your own heater core and get you through the winter.

If the water pump were faulty then the car engine would overheat due to lack of coolant circulation.

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The Water Pump theory had me thinking we'd have more of an Overheating Issue.. Right Now the timing with Christmas & Boxing Day to purchase a Thermostat & Gasket.. Plus I'm sure we're running out of decent temps to be working outside with this.. Cheers and Thanks for the Comebacks.

That is not a normal explanation, unless the water pump impeller has been eaten away. I've only seen this a few times, where the cooling system has been really neglected. That's why it's best to change the coolant every two years.

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Originally Posted by TxGreaseMonkey

That is not a normal explanation, unless the water pump impeller has been eaten away. I've only seen this a few times, where the cooling system has been really neglected. That's why it's best to change the coolant every two years.

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This is My Son's Car so It's a 2nd hand Description & Part Translation.. lol.. He says if he we're to step up the RPM's just a couple notches while at a Traffic Light (Std.Trans.) he builds up Heat...

If it were my car, I'd reverse flush the heater core, install an OEM thermostat, and refill with coolant. It's easy to do and shouldn't take long.

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Originally Posted by TxGreaseMonkey

If it were my car, I'd reverse flush the heater core, install an OEM thermostat, and refill with coolant. It's easy to do and shouldn't take long.

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Thank You, I Conquer...

Had a Ford Ranger with the same issue. Back flushed the heater core and all kinds of fine junk came out. Works fine now, plenty of heat.