I just replaced the heater core, I filled the core up through the  heater core lines. I then burped the system. The thermostat is working properly and the radiator has been flushed multiple times with no visible rust.

 

This was a problem with the old heater core but I chalked that up to a rodent building a nest on top of the heater core. It may not have been the entire problem.

 

My question is, if I accidentally swapped the lines going and coming from the heater core, would this cause the heater core not to get warm.

 

If it's not that. I guess, I must have a vapor lock?

I dont think it would make a difference which way the coolant is pumped through.

there should be a valve just before the core that regulates the flow via the linkage from the control panel on the dash. other than that i would check the flaps and cables inside the unit and make sure they are opening and closing properly and your not getting vent air..etc.

There is no valve on the Brat. Your air mix door is most likely not moving. You need to check the cable from the control to the door and make sure it is attached and the door is moving. The Brat also has no vacuum controls for the heat, so don't be looking there.

Ok thanks, It's raining today so I can't check it out, but I think the temp/air mix door? cable came unhooked.

The cores probably gunked up, try flushing it with CLR. There are a few videos of this on YouTube. There should be a bypass valve on the side of the heater core box and make sure that's moving I've had them come unhooked.

Edited August 28, 201312 yr by mikaleda

It was the cable for the heat control. It came unhooked. Works great now, thanks.

I would suggest avoiding using corrosive flushes.  The aluminum in the system will not like them, and it is hard to properly neutralize the acids.

I would suggest avoiding using corrosive flushes.  The aluminum in the system will not like them, and it is hard to properly neutralize the acids.

by flushed I ment, drained it when I was chasing down an overheating problem, then drained it again so I could add the correct amount of antifreeze. Drained it when I was swapping the heater core, then refilled with the correct amount of antifreeze.

 

  :water:

I would suggest avoiding using corrosive flushes.  The aluminum in the system will not like them, and it is hard to properly neutralize the acids.

I'm not sure if you were mentioning this for what I said, but the process only goes to the heater core wich is copper. It is very important to get all of it out though by flushing it several times with water

I find it not to bad to remove the end tank clean core out and resoder the end back on then they work great