- incorrect operation of the radiator cap valves. Check the opening pressure of the outlet valve, which should be (0.5±0.05) kgf/cm²;
- insufficient tightness of the radiator cap gasket. In this case, replace the cap;
- radiator leak. Check the radiator for leaks. To do this, close the filler neck and radiator pipes, place it in a bath of water and supply compressed air to the radiator at a pressure of 1 kgf/cm². There should be no air leakage for at least 30 seconds. The radiator can be checked for leaks without removing it from the car, for which you should plug the radiator pipes and fill it with water, create a pressure of up to 1 kgf/cm². There should be no water leaks. Fix a small leak by soldering with soft solder (at the automobile plant, soldering was carried out with POSSU 30-2 solder).
Damaged upper and lower radiator tanks are repaired by applying pads:
- cut brass strips 0.8-1.5 mm thick and 10 mm larger than the damaged area;
- clean and tin the overlay and the damaged area, then solder the overlay to the damaged area;
- plug damaged radiator cooling tubes by soldering the upper and lower ends. It is permissible to plug no more than three radiator tubes;
- weld the breaks and cracks on the radiator mounting plates with gas welding.
Eliminate fluid leaks in hose connections by tightening the clamps or replacing damaged parts.
[The original source is located on the website: VAZBOOK]