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Message: <blockquote data-quote="e34_lover" data-source="post: 676135" data-attributes="member: 16259">Firstly, I need to say I don't know much about the N52B25 but I do have some ideas as to why this is happening.If I am not mistaken the N52B25 has an electrical waterpump unlike the old crankshaft driven pumps. I believe the thermostat is also now electrical. If your temperatures are going up and down sporadically, it could be the thermostat that is getting wrong information about the current water temperature and not opening to cool the coolant. Unsure if the coolant temperature sensor is built into the thermostat or if theres a seperate sensor. Also, I don't know if the waterpump can be driven at different speeds dependant on temperature or if it is fixed. If it is dependant on temperature, it could also be receiving wrong information and not pumping at the required speed.Does the temperature go up and down while driving normally or stopped at traffic? If this happens only while you are stopped, your high speed fan relay may be faulty or your fan may not be working at all. You will need to check this yourself.Whats the mileage on your car? The waterpump IS a service item and should be replaced during the life of the car. I believe that spending some money here and preventing a major failure is more than worth it.Your radiator shouldn't get clogged unless there is either a headgasket leak causing oil to gunk up your cooling system or if there has been tap water used in the cooling system, depositing minerals and rusting internals. Hope this helps!</blockquote>

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