Coolant Pump - BMW B46TU Reference Manual

B46TU￿/￿B48TU￿Engines
3.￿Cooling￿System
3.4.￿Coolant￿pump
The￿layout￿and￿function￿of￿the￿coolant￿pump￿have￿been￿revised￿and￿adapted￿to￿match￿the￿cooling
concept￿of￿the￿B46TU/B48TU engines.
Coolant￿pump
Index
A
B
A￿pressure￿relief￿valve￿is￿installed￿in￿the￿mechanical￿coolant￿pump￿housing.￿In￿combination￿with￿the
heat￿management￿module,￿the￿pressure￿relief￿valve￿on￿the￿one￿hand￿ensures￿that￿the￿engine￿operating
temperature￿is￿reached￿more￿quickly,￿while￿at￿the￿same￿time￿reducing￿leaks￿and￿component￿damage
due￿to￿high￿pressure￿in￿the￿cooling￿system.
If￿an￿excess￿pressure￿of￿more￿than￿2.2 bar￿(32￿psi)￿builds￿up￿in￿the￿coolant￿circuit,￿the￿pressure￿relief
valve￿opens￿and￿releases￿a￿bypass￿channel.￿The￿coolant￿is￿now￿exclusively￿circulated￿in￿the￿pump
body.￿Once￿the￿pressure￿drops￿below￿2.2 bar￿(32￿psi),￿the￿pressure￿relief￿valve￿closes￿and￿the￿coolant
is￿again￿routed￿through￿the￿coolant￿ducts.
26
Explanation
Pressure￿relief￿valve￿closed￿(pressure < 2.2 bar￿/￿32￿psi)
Pressure￿relief￿valve￿opened￿(pressure > 2.2 bar￿/￿32￿psi)