Where Is The Piss Point On My Water Pump

If its only bubbling once it reaches a very high temperature then the radiator cap is doing its job. I would look into replacing the cap though, seems simple but if the cap is not allowing the system to pressurize then the coolant can boil at a lower temperature.

Also, there is the potential that the cooling system is partially air locked. How long has it been since the cooling system has been serviced? Worth a look. The temperature of the coolant can sometimes reach 250 to 275 F (121 to 135 C). Even with antifreeze added, these temperatures would boil the coolant.  To prevent this, the cooling system is pressurized, which further raises the boiling point of the coolant. Most systems have around 14 to 15 pounds per square inch (psi), which raises the boiling point approximately 45 F so the coolant can endure the high temperatures produced in the engine. - See more at: http://motorist.org/articles/Cooling-System-Maintenance#sthash.IbHNtR0q.dpuf

I hope this is helpful to you!

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