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Discussion Starter · #21 ·
I got the same problem with my 3.9 engine, with an impressive 108 celcius (about 226 fahrenheit) before the fans start, which seems very high to me. On some cars (Volkswagen I think), one of the two fans start at 200 and if the engine reach 220 the other fan engage. Is that how it is supposed to works too on the 3.9 engine ?
I believe but I'm not sure that our fans have a low and high speed to them.

220 isn't real high, I've heard some engines are designed to run hotter to help burn cleaner (emissions) But it's higher than I'd like.

If you haven't changed the coolant lately try that and I'd add a bottle of "Water Wetter" I think it made a difference in my 3.5
 

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I got the same problem with my 3.9 engine, with an impressive 108 celcius (about 226 fahrenheit) before the fans start, which seems very high to me. On some cars (Volkswagen I think), one of the two fans start at 200 and if the engine reach 220 the other fan engage. Is that how it is supposed to works too on the 3.9 engine ?
here's the cooling protocol (all engines):

The PCM or ECM commands Low Speed Fans ON under the following conditions:

• Engine coolant temperature exceeds approximately 106°C (223°F).

• When A/C is requested and the ambient temperature is more than 50°C (122°F).

• A/C refrigerant pressure exceeds 1 310 kPa (190 psi).

• After the vehicle is shut off, if the engine coolant temperature at key-off is more than 140°C (284°F) and system voltage is more than 12 volts. The fans will stay ON for approximately 3 minutes.

The PCM or ECM commands High Speed Fans ON under the following conditions:

• Engine coolant temperature reaches 110°C (230°F).

• A/C refrigerant pressure exceeds 1 655 kPa (240 psi).

• When certain DTCs set
 

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50/50 with a 15 lb cap good for 265, the fans will make sure it won't exceed 230.

Lot of head gasket issues with iron block, aluminum head, not the same expansion rate.
 

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I live in a Country with a 2010 G6, GT, with the 3.5 DOHC, with A/T. Where are the hotter thermostats you mention in this thread? :)
I recently replaced the thermostat in my 08 3.5 and there was only ONE temp thermostat offered thru numerous parts stores and online. Why do you want one that opens at an even higher temp? IF you don't seem to get enough interior heat after T-Stat replacement, then you need to check HVAC door functions(they're electrical and not cable operated) or try flushing the heater core.
 
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