ive posted about this a couple of times and I really need help with this. Ive got some pics this time to show what is going on. Ive got a guy thats going to do a pressure test of the cooling sys. and he says it could be some internal seal causing the prob. and a pressure test will let me know. anyway here are the pics. 1st pic is driving about an hour at night really cool outside temp. i took the pic when i pulled in the drive way. the second pic is driving for about an hour in the middle of the day with 95 degree weather. so why such a difference?

 

it's quite possible it's either got the wrong temp sensor in the engine or a previous owner swapped out the cluster. miss matched ohm values between gauge and sensor will give inaccurate readings. get a new sensor and see if that works. could have the wrong t-stat as well. should be i think a 180 or 185 degree.

 

I dont think it has any thing to do with the gauge or the sensor readding wrong because if you look at the pic where the temp is low its idleing at about 1100 or 1200 like the thermo wax hasnt expanded all the way. and on the second pic where the temp is normal idle is where its supposed to be. Also I changed the tstat to mazda oem Im putting a new fan clutch on this weekend and ill have a chance to check out the radiator. If any one has any other ideas that might help please let me know. Im strugglin here. not to mention the pressure test of the cooling sys. some time this week. Still dont understand how it can vary that much just from outside temp?

 

I believe the S5 temp gauge has three positions only. They are low, meduim and high which is unlike the S4 gauges which have the ability to indicate a reading anywhere between low and high which is unlike yours.

 

well just throwing out ideas like was asked for. i do know that the sensor resistance has to be right or the gauge doesn't read right. if everything's fine, be glad it does actually run that cool. outside of this and others i've mentioned, i wouldn't know why the gauge is reading cooler than usual.

 

I know and i really appreciate what you and everyone else has done to help. Its just really frustrating because i want things to be consistent. And it is kinda awesome that it does run really cool but again consistency. Again thanks alot for all the help because this is like the third time ive posted about this.

 

Test the thermostat. It may be missing/stuck open.

 

I would like to add a little fact. Tradiator hoses look like a pregnant womans ankles (swollen) as soon as the car gets any temp. to it. even low or high temp the hoses always look swollen. and if you try to squeez them they are really tight.

 

The radiator hoses

 

replace the hoses. they're deteriorating from the inside and will burst at any time.