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Heater core flow rate

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Jul 20, 2001
Herndon, VA
I haven't seen much talk about this, but I was wondering how much water should be coming out of the intake valve of a heater core? Should it fill the entire hose up, or should it just be trickling due to the size of the passes inside the core?
Once you get all the air air of the system, the hose should be completely full regardless of the flow rate. It sounds to me that you have air in your system.

BTW heater cores are generally regarded as one of the least restrictive radiators when it comes to flow.