No coolant flow to brand new heater core

[brillo_76]

Is it possible that your thermostat is just bad? As a defective thermostat will do exactly what you are seeing. The works when first start up then after warm up no heat. Is sounding to me like the thermostat is sticking open. A stuck open one.

Do you know of the thermostat is oem or aftermarket?

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[rcvxl24]

Is it possible that your thermostat is just bad? As a defective thermostat will do exactly what you are seeing. The works when first start up then after warm up no heat. Is sounding to me like the thermostat is sticking open. A stuck open one.

Do you know of the thermostat is oem or aftermarket?

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I could be wrong, but I don’t think it’s the thermostat. A few reasons:
- brand new OEM thermostat as of fall 2021
- that wouldn’t explain the lack of flow to the heater core
- my coolant temp always stays at ~188F, if it was stuck open I’d imagine it would fluctuate based on demand and ambient temperature


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[19963.4lsr5]

Pull out the thermostat and force water through the coolant bypass and let it run until you see clean water and no chunks. It’s the only thing that made sense. Hopefully it’s the issue.

Potentially that crap will migrate into your new heater core so back flushing that is a good idea also.


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[gamefreakgc]

Sounds like somebody put a bottle of stop leak in there. That stuff ends up doing more damage than it helps.

 

[brillo_76]

+1 stop leak was used in the past. This would explain the clogging.
Agreed the thermostat would have the coolant temp fluctuate especially if sticking open.

That stuff will plug all kinds of things up. It really should be completely pulled off the market. :/

 

[rcvxl24]

Yes, I agree stop leak was likely used by a previous owner. Reason being, there is an external repair job on my radiator (that surprisingly doesn’t leak) that was probably done in tandem with the stop leak. Sometime in the future I’ll replace the radiator with a new Denso, but it’s not a priority for me right now.


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