car gauge going to hot but jumping back n forth
Can working, no leaks
may actually be any number of concerns...coolant flow...one might use a lazer spot thermometer to check the temperature at the inlet and the outlet pipes....the thermostat may be sticking and only opening when it gets way above 295.....apparently you've not and an overboil...the actual temperature gauge may not be sufficiently grounded...and poppin' up with the bogus info .so from the black terminal assure the connection to the chassis/ground has not been corroded...might you measure the voltage at the gauge when this occurs...and more....
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