jesseber

Three months ago, my 2006 Z started to overheat. Changed the thermostat and car was perfectly well behaved for two months.

Then one day I overheated out of nowhere again, but there were no symptoms of a hot engine outside of the gauge saying so. Replaced the gauge sensor and after a 15 minute drive all was right again.

Another month goes by and now my fans would come on after 5-10 minutes of driving like normally, but they would be on absolute maniac mode and more or less not turn off for the rest of the drive. After two days of that, my temp began fluctuating from a needle's width below the middle to a needle's width above. I decide to bleed the system and there was, in fact, some air in there, but burping it out gave no change, so I went ahead and replaced the radiator & cap. Car then began to give me full send H reading, but engine/bay still showing no signs of overheating (normal amount of heat coming off engine, no abnormal noises, can rest hand on block, plenty of give in upper hose), so I tried replacing the gauge sensor again. No change.

I'd like to note that at no time did the car burn/leak coolant during all of this. No smoke/condensation from exhaust and oil looks fine, so I'm not inclined to believe that this is a head gasket problem. For the record, my water pump was changed about 40k miles ago. At this point I'm not sure what to do.

TL;DR: My fans and gauge are telling me I'm red hot, but my engine bay suggests otherwise. Any advice would be very appreciated as this is my only car atm and catching rides isn't fun.

nizzan4u2nv

iTrader: (1)

Do the interior fans blow hot air when set to full hot? If not, thats a clear indication that there is still air in the system. Make sure both the upper and lower rad hoses get hot as that is an indicator that the thermostat is opening and coolant is flowing throught the system. Did you use an oem coolant temp sensor? Get yourself a OBD scanner with live data so you can see what your actual temperature is. The oem gauge has no clear indication of actual coolant temp nor is it even accurate. 3/4 of the oem guage is already 230*f plus on live data which is already beginning to boil coolant.

jesseber

Fans not blowing cool inside and lower hose is cold. I guess I need to take this somewhere to be bled professionally.

I did not use OEM sensor.

So is this also a sign that the thermostat needs to be replaced with an OEM one?

nizzan4u2nv

iTrader: (1)

Ive had good luck bleeding with a spill free funnel. Takes a while but it gets the job done. Ive seen some people use the coolant reservoir to bleed the system as well. They hang it from the hood latch.

icer5160

iTrader: (4)

If the lower rad hose is cold after running the engine for 5 minute or so, then most likely your thermostat is stuck closed! Serious problem that needs to be resolved, it's a cheap/easy job to do, but could be catastrophic if not handled quickly! Make sure you bleed/fill the coolant system with the bleeder port near battery box (on heater core inlet hose) opened up! Failure to do so will trap a lot of air!
-Icer