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Ask discostew Your Own Question
Category: Australia Car
Satisfied Customers: 88
Experience:  proprietor at port steering & alignment
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The temp gauge goes up then drops straight back down on my

Customer Question

The temp gauge goes up then drops straight back down on my vt commadore
JA: What is the make/model/year of your car?
Customer: 1999 berlina
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: I just did thermostate radiator coolant leads and plugs
JA: Has the vehicle overheated in the past? And what about servicing? Is it up-to-date on oil changes?
Customer: Yeh a few weeks ago thats why i did all that or and i did oil change to jusr dont no why it goes up then staight down nomaly it would stay up if its hot ha
JA: Anything else you want the mechanic to know before I connect you?
Customer: Dont thinl so
Submitted: 11 months ago.
Category: Australia Car
Expert:  discostew replied 11 months ago.

Hi im stew a mechanic here in australia,your berlina,,,im assuming its a V6?is this right,have you ensured there is no air in the system?,as the motor is warming up the heater control needs to be in the hot section (to ensure the heater core fills with water/evacuates air from the heater core),once hot(top hose hot,shows thermo is open ,flowing hot through the radiator)you need to replace pressure cap,gain a little heat(pressure)then bleed air from system via bleeder valve on top of thermo housing.air pockets will cause the fluctuation ,the temp gauge sender can monitor the temp of water not hot air,cheers stew