I have a partially obstructed heater core. I removed the heater core hoses and flushed the core in both directions several times using Prestone radiator flush with boiling water. Some particulate crud comes out but man it's a slooowwww process.
Iím wondering if I couldn't I use the old two-part radiator flush/neutralizer (oxalic acid/baking soda) on the heater core only? From what I can tell (based on a few photos Iíve seen on the Ďnet) the water tubes and the spiral mixer elements inside the tubes seem to be copper or brass or bronze. The fins are aluminum but they don't seem to come in contact with the coolant. I don't know about the ends of the core--I assume the copper/brass/bronze tubing is just bent into a 180 degree turn. Does anyone know if there is anything but copper/brass/bronze in the coolant flow path in the heater core?
Since oxalic acid is stronger than the Prestone (citric acid, basically lemon juice) it should shorten the process. Any reason I shouldnít do this? I know this will likely be temporary but I donít have the time/money to replace the core now.
I see people use CLR but when I read the label it says NOT to use it on copper, brass, aluminum and a whole host of other metals. So that gives me pause. At least oxalic acid was used as a radiator flush. Any thoughts?