So i went to go get my car tuned and the tuner ask what temps. are you running while driving i said 230-235 he says thats way too hot, and i should be around 190?? He says he will try to tune the car .... but dosent know how well it will work with the high temp numbers. I have heard that running around 230 is ok?? please chime in if im ok ... or if i should get a lower thermostat and the fans reprogrammed when i go back in for a tune.

 

Get another tunner...

Mark

 

On the highway at 55 or greater you should be seeing temps between 190 and 200. If not you probably have some debris blocking your radiator or your center spoiler isn't in place or is flexed backwards. If you are seeing temps of 230-235 in traffic you need to watch them and see if they go up and down between roughly 219 and 235. If they do and you are seeing 190 to 200 on the highway then your cooling system is OK. On hot days at 75 mph on the highway in 6th gear I see 190 with a 195 thermostat.

Bill

 

The sweet spot is anywhere between 190-200. Get your fans programmed if you want to run cooler temps in city driving. Dearborne is right regarding freeway driving at any speed about 60MPH, you should see 190-200 without programming your fans. I think 235 is too high for city driving but many on the forum say this is ok for the C5 b/ made to run at these temps and be O.K.

 

A lower thermostat won't change anything, other than causing the engine to waste fuel getting up to its regular operating temperature. On the Highway your coolant temp should be about 195 degrees and oil should be about 205 degrees (plus/minus 5 degrees for both readings).

In traffic or at a long stop light it is common to see the coolant temp rise to the area of 230 degrees (especially on a hot day) at which point the radiator fans will kick in to improve air flow through the radiator.

Modern engines are designed to run "hot" as it improves fuel econonmy and helps them meet emission targets. A "cold" engine is a heat sink that is robbing power from the burned fuel. Heat taken to heat the engine is wasted power.

 

my car's oil runs 230 -235 on the freeway.... i dont have a radiator shroud on my car. so im guessing i should just get a thermostat and my fans reprogrammed??

 

If the oil temp is staying at 230-235 after, say, a steady run at 60 MPH for 20 minutes, then that does sound high. After driving around town and getting the oil that "hot" it will take at least 10 minutes on the freeway before I see it start to drop down, and probably another 10 minutes before it is in the range I expect of about 200 to 205 (this is based on a "warm" day here in NorCal.

I suspect the lack of a radiator shroud (I'm assuming you're referring to the seal around the radiator and A/C condenser) is your biggest problem. The Service Manual states :

"The cooling system uses deflectors, air baffles, and air seals to increase system cooling. Deflectors are installed under the vehicle to redirect airflow beneath the vehicle to flow through the radiator to increase cooling. Air baffles are also used to direct airflow into the radiator to increase cooling. Air seals prevent air from bypassing the radiator and A/C condenser. Air seals also prevent recirculation of the air for better hot weather cooling and A/C condenser performance."

A lower temp thermostat does NOTHING except increase the time (by a few minutes) it takes the engine to come up to "normal" temperature. A 160 degree thermo opens sooner than 195 thermo, but in both cases the engine will eventually reach the same operating temperature.

If you've removed the air seal, having the fans come on earlier probably won't help a lot as they'll be recirculating warmed air through the radiator. I'd bet the Chevy engineers spent a lot of time working out how to get the cooling system to work well given the body design of the C5, especially the nose area. I'd recommend you consider putting back whatever "shroud" or other components of the system you've removed. I strongly suspect you'll find your cooling system will work properly after that.