B3.9 and B5.9 Series Engines
Cooling System Diagnostics (008-020)
Section 8 - Cooling System - Group 08
As stated in the coolant discussion, an obstruction in the
passages can interrupt flow.
Radiator, Fans, and Shutters
Air forced through the fins of the radiator by a fan cools the
coolant pumped through the radiator. Environmental debris
(paper, straw, lint, dust, etc.) can obstruct the fins and stop
the flow of air, which will reduce the cooling effect of the
If the fan is belt-driven, a slipping belt will result in slower
fan speed and reduced cooling. A malfunctioning auto-
matic belt tensioner can be the problem.
to make sure they are not causing excessive belt vibration
Interruption of the circuit to an electrically driven fan can
result in insufficient airflow and cause the engine to run hot.
NOTE: Make sure the temperature sensor is functioning