240 sounds awfully high, guys...210, 220...that should be peak for normal driving...4-6k rpms? kinda pushing it, eh?.....Most cars "back in the day" ran at 180....I guess the higher temps help the epa rating...but not our motors in the long run.
I would love to hear from a tech or mechanic as to what temps our cars should be running at.
One note about the gauges...unless you have a mechanical gauge that reads actual temps...the gauge you are seeing may only be a glorified idiot light. Thats why they go to max "temp" or 240 and dont move from there.
The temps should rise with the thermostadt closed, then, the thermostadt opens and fan comes on to lower the temp to a certain point and then things cycle again....if your gauge is not showing temperature fluctuations while following the curve (The sine wave or sinusoid is a mathematical curve that describes a smooth repetitive oscillation) then, you have an idiot light gauge, for lack of a better term and not an actual gauge.
Im looking into getting a set of 3 gauges to replace my ashtray area so I can see real time at a glance my water temp, oil pressure and charging system health....I want to know if something is going wrong before the computer parameters max out and switch on the idiot lights.