I battled a cooling problem a while back. Flushed the system multiple times to no avail. Then I had the radiator rodded out and everything was fine for a day, but the problem quickly returned. Running out of ideas, I installed a Tefba cooling system filter, flushed the system again and cleaned the radiator and no problem since.

It turned out there was (for lack of a better term) crud in the system. It looked like dirt/rust particles that presumably were slowly breaking loose from walls of the coolant passages, lodging in the radiator and inhibiting coolant flow. The filter did trap a bunch of particles that I saved in a jar to keep a running tab of what was in there.

Last edited by KWF340; 09/11/19 02:38 PM.
1968 Charger R/T, 440 Auto, GG1;
1969 Super Bee, 383, 4-speed, T5;
1969.5 Road Runner, 440-6, 4-speed, 96;
1970 Duster 340, 4-speed, EV2;
1970 Charger R/T SE, 440 (496), Auto, EB3;
1970 Dart Swinger 340 (416), 4-speed, EV2;
1970 Corvette coupe, LS5, 4-speed, Daytona yellow;
2000 Corvette coupe, LS1, 6-speed, Twin Turbo, Torch red.