78 Degree thermostat

[AuSpecVr4]

Hey guys

I have noticed this recently and i'm hoping that my head isn't cracked but i would like some advice on what to do. The car runs great and pulls hard, i have a 78 degree thermostat in my car and when i'm driving coolant temperature gets to 95-1xx degrees, it gets to 100 degrees and sits there for a couple of minutes of driving when the coolant temp drops my check engine light goes off, its set to 100 degrees. I've heard that in some cases a colder thermostat can cause more problems then it solves? i have a aluminum evo 3 radiator with the stock thermo fan on and on idle it will creep to 100 and wont come back down and the fan is on. Is it because its getting hot its flowing more water earlier and not allowing the radiator to cool the water quick enough? so if i put in a hotter thermostat, the radiator would have time to cool the water? I have broken my alternator belt twice while driving.. and continued driving for a couple of hundred metres before pulling over and turning the car off. Would this of been enough to have cracked my head and is there any easy way of checking this? during ECMlink log, i saw at least 115 degrees at the thermostat housing which is after the engine block and head.. after the belt had broken, i could only imagine how hot it would of been inside the cooling system and inside the engine/head. That happened a month or two ago now, the car still overheats on idle but it doesn't miss a beat and revs out fine.

Cheers, Brock

 

[fuel]

115deg (celcius) is nothing to worry about. That wouldn't have cracked your head if it were for just a few hundred meters. I snapped the fan belt on my 82 Galant GT 4G63 SOHC turbo and drove 2km home and it didn't damage the engine - the temp gauge barely moved beyond half.

I think it's a combination of your thermostat being too cold a temperature, and your radiator being too efficient at speed. I would fit the recommended thermostat (I think it's either 82 or 88deg celcius).

 

[AuSpecVr4]

okay cheers, this head seems to be bullet proof. I will try to put a hotter thermostat back in, cheers

 

[bazeng]

Agreed. I had a 78 deg tstat and the main problem is that I couldn't get the correct fan switch sensor to suit. You really want everything to work together. With the std fan switch and lower tstat it would cause the temp to fluctuate when idle then on cruise. I went back up to the std tstat and it was much better overall.