BMW E38 water pump and thermostat
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Should you replace the E38 water pump preventively?
If the service history is unknown, it is worth replacing the pump and thermostat together. The pump can fail without warning at around 200,000 km, and replacement is cheap and easy. A leaking weep hole warns before complete failure.
What should you do with the thermostat when replacing the pump?
The thermostat and its housing are replaced at the same time, and the thermostat and housing gaskets are renewed. On the M60 the normal thermostat is an 85-degree one.
Why does the E38 engine temperature stay low?
The thermostat may have stuck open, so the temperature does not rise to normal. On the M73 the normal operating temperature is about 95 degrees plus or minus 3. The temperature sensors for the instrument cluster and the engine management are different sensors, so it is worth comparing the readings.
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