Radiator Expansion Tank

The MGA radiator is a 'total loss' system in that water that escapes through the pressure cap due to expansion escapes down a drain pipe to the ground.

All modern cars incorporate expansion tanks that contain this lost water and then allow it to be drawn back into the radiator as the water cools.

Such a system can be incorporated into the MGA using an MGB expansion tank (see photograph).

In this set up, the MGB expansion tank and its retaining bracket is attached to an L-shaped bracket which in turn is attached to the radiator top retaining bolt.  There is approximately 6mm clearance either side of the tank between the radiator and the front carburettor bowl.  A piece of pressure piping attaches the expansion tank to the radiator overflow pipe.  The radiator pressure cap is transferred to the expansion tank and a blanking cap fitted to the radiator, allowing unrestricted water flow between the radiator and the expansion tank.

The blanking cap was a standard cap that had its innards removed and Araldited to make airtight around the remnants of the central shaft.  A large rubber washer was inserted to make an airtight seal around the top of the filler neck.