Expansion tank cap (Renault 19)

Since the cooling system operates under pressure, the expansion tank cap plays an important role:

• The gasket, when the cap is screwed on, prevents the pressure in the system from dropping.
• If the pressure in the cooling system on a warm engine exceeds 1.6 bar, the pressure reducing valve opens and a small amount of water vapor is released to equalize the pressure.

Checking the pressure reducing valve

The expansion tank cap pressure reducing valve is checked using the device described above with the appropriate attachment:

1. Increase the pressure until air begins to come out.

2. Measure the pressure and compare the result with the data on the expansion tank cap.

(Original version on our portal: renaultbook.ru)

Note: Recommendation: If the valve is faulty, the rubber gasket is damaged, or sediment has accumulated on the lid, it should be replaced.