Water Leak Check

WARNING: This page is about a different car, the 2005 BMW 530i, 2005 BMW 525i, 2004 BMW 530i, and 2004 BMW 525i. However, it is still accessible from the selected car via links, so may be relevant.

WARNING: Danger of scalding!
Only perform this work after engine has cooled down.

Checking Pressure Drop In Cooling System:

Open cap on coolant expansion tank. Fit special tools 17 0 101 / 17 0 113.

Build up gauge pressure of 2 bar, wait approx. 2 minutes.

Cooling system is impervious to leaks if pressure drop is max. 0.1 bar.

Fig 1: Checking Pressure Drop In Cooling System

Courtesy of BMW OF NORTH AMERICA, INC.

Checking Pressure Relief Valve In Cap:

NOTE: Coolant residue can cause the pressure relief valve in the cap to stick, therefore repeat the check procedure on the cap 2--3 times.

Screw cap (1) onto special tool 17 0 114.

Build up pressure with special tool 17 0 101 (hand pump); observe pressure gauge to ascertain when opening pressure is achieved.

Opening pressure of pressure relief valve.

Fig 2: Installing Screw Cap Onto Special Tool

Courtesy of BMW OF NORTH AMERICA, INC.