Coolant expansion tank: common defects and their signs

1. Corrosion and clogging of the expansion tank cap valve.
   • Temperature of the engine increases.
   • The passenger compartment warms up insufficiently during winter time.
   • Smoke appears from under the hood.
2. Valve jamming.
   • Pressure in the cooling system increases.
   • Pipes and clamps crack.
   • The tank may inflate or explode.
3. Tank body cracking.
   • Antifreeze consumption increases.
   • The engine overheats.
   • Efficiency of the cooling system worsens.
   • Cooling liquid leaks.

How to repair or replace coolant expansion tank?

Manufacturers recommend to replace the car coolant expansion tank once a year. However, if the component breaks down earlier, it is necessary to repair or replace it immediately.

The cooling system expansion tank can be repaired, if the cause of its malfunction is in the cap valve. In this case, you can just replace the cap. Make sure the spare part is marked identically to the broken one.

If the housing is cracked or damaged, the coolant expansion tank requires replacement. It can be performed single-handedly, as the procedure is quite simple. In order to replace the part, you need to:

1. After the engine cools down, drain cooling liquid into a spare container.
2. Loosen the clamps of steam- and liquid-discharge hoses and remove them from the tank.
3. Remove tank fasteners from the bracket.
4. Lift and tilt the tank in the direction of the headlights to release it.
5. Loosen the lower clamp and remove the hose from the tank pipe. Remove the tank.
6. Install a new one in reverse order. Fill with antifreeze up to the mark on tank walls.
7. Start the engine and check for leaks on tank walls and hoses.