A cooling system pressure test is used
to check for internal leaks. Some of the
common sources of internal leaks are a
faulty cylinder head gasket, a cracked
cylinder head, or a cracked cylinder
block.
To do a cooling system pressure test, a
special pressure tester is needed.
WARNING!
At normal operating temperature the
cooling system is pressurized. Allow
the system to cool before opening.
Release the cap slowly to allow safe
release of pressure.
With engine cold, install pressure
tester (BMW special tools 17 0 002/17
0 005 or equivalent) to expansion tank.
Pressurize system to specification
listed in
Table a
.
Pressure should not drop more
than 0.1 bar (1.45 psi) for at least
two minutes.
If pressure drops rapidly and there
is no sign of external leakage,
cylinder head gasket may be
faulty. Perform compression and
leak-down tests as described in
100 Engine–General
Also test expansion tank cap
using pressure tester and correct
adapter (BMW special tool 17 0
007 or equivalent). Replace faulty
cap or cap gasket.
Table a. Cooling system test
pressures
Component
Test pressure
Radiator
1.5 bar (21.75
Radiator and Cooling System
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Summary of Contents for 1999-2005 M3
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