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1998 BMW 540i Question: what are the reasons for the cooling system to boil or fluctuating cooling temp

 

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p dog, Pacifica, CA, January 04, 2012, 23:17
 Rookie

also heater is not working properly

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  • Answer #1

    January 04, 2012, 23:47
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     Master

    Sounds like the thermostat is bad. Need to replace soon but make sure coolant is at proper level and not leaking. Other cause is heater core obstruction not allowing fluid to flow through properly. Hopefully, not the water pump.

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  • Medium-star Best Answer
    British European Motors from BOSCH Service, January 09, 2012, 11:30
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     Enthusiast

    Thermostat problem, most likely.

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