SHO's temp is unstable...why?

[frosho]

With the cooling system full and clean and everything working as it should, why do some people still get a fluctuating temp besides that the car is old?

That's just how the system works. The thermostat restricts coolant flow during warm-up, and then opens up at operating temp. Then when it's up to temp, it relies on airflow through the radiator to keep things from overheating. On the highway, there is a lot of constant airflow through the radiator, which keeps the coolant at a relatively constant temp. When you're driving at lower speeds, there isn't enough air moving through the radiator to keep temps down, so the coolant temp will rise until the fan(s) kick on. They will pull air through the radiator until the coolant temp drops to a predetermined set-point, and the process repeats itself. That's where the fluctuation comes from.

 

[SHOstuff]

Bit why do newer cars don't show that fluctuation?

 

[Sho Amo]

I use this when I'm burping a coolant system. It was free.

 

[frosho]

Bit why do newer cars don't show that fluctuation?

I dunno... improved technology?

Also, the stock "gauge" isn't the most accurate thing in the world, and doesn't give you a temperature reading. You need a real coolant temp gauge to see how much it's actually fluctuating.

 

[ViPER1313]

Bit why do newer cars don't show that fluctuation?

My 2007 Grand Prix has a lot larger temperature swing than my SHO does.....

GP: 195 degree thermostat but the fans don't kick on at low speed until 221 degrees, or to high until 228 degrees. The temp gauge will be 100% in the middle until stop and go driving, then it will creep (what I consider pretty close) to the top of the gauge, then cool off. Never over heats. Supposedly it acts this way to save gas (This is also the only car that I have ever driven that I am scared to drive ******* a 95+ degree day - the motor will run 220 degrees even on the highway and the transmission can peak 240+. Once again, the car will not overheat - just the way it is.)

So long as it is in the NORMAL range, don't sweat it.

 

[SHOZ123]

If the system is air tight and the cap holds 15 psi there is no need to burp the system as the air will be removed after a few heat cycles.