My 2006 Nissan Altima over heated, the mechanic replaced the radiator; said it was leaking. I drove the car away and the temp gauge went up again. I returned to the shop; they replaced the thermostat
(upper and lower). The temp gauge still
goes up returns down to below the center
periodically when I'm driving. Can you
please tell me what could be the problem?
It sounds like there is air in the system. Did they use a vacuum type coolant machine to fill the new radiator? if not then there is probably air trapped. Now days you can't really "bleed" they system anymore. So you have to pull a vaccum on the cooling system then fill by switching the vacuum to liquid fill on a coolant flush machine. I would ask them how they refilled your coolant
Thanks; I'll check this out.