I've had my 06 Honda s2000 for a good year now, always stayed at a nice 8 bars. I was in a parking lot, car started to overheat, at least I think. I looked up from my phone, looked at it last at the most 5 minutes, and it had about 11 bars I would say, I turned it off before I counted. Let it be, had no issues driving it short distances. Drove pretty far actually and it did fine until later in the night it reached 9 bars, but from what I have seen thats not actually too bad. But to be safe I figured I'd check it out.I had some speculations that it was the thermostat. Fast forward to know, coolant drained, thermostat replaced with an OEM one from hondapartsnow, new radiator cap from O'Reilly, not honda brand, then Bled through DIYguys method, swtitched to Billmans method bc It made me feel better. Bleed cap no bubbles, air vents burn, all good I thought. I haven't driven it a whole lot but when I do i have an OBD2 port reader to my phone. After a few minutes it gets to about 172F where it slowly makes it up to 176F. Driving at a constant 55mph in 60F weather, it stays at 176F, kind of drops to 174F then right back up. It doesn't seem to get higher until I come to a stop. I was parked at the gym earlier, car was idling for about 5 minutes Id say and the Temps got to about 190F, mightve kept going but I turned it off instead. Drive back same thing, 174F-176F. Is it a faulty Thermostat? Should I bleed the system some more? Get a OEM radiator cap? Takes a few minutes of driving to go up from 7 bars to 8 bars.

Thank you!

 

Got plenty of heat? The temperatures seem normal. You'll feel better with an OEM radiator cap but I doubt anything will change. The DBW cars rarely indicate anything other than 8 bars and the fans rarely come on while the car is moving but will at idle.

-- Chuck

 

The reason most manufactures don't use a actual numbered temp gauge is how much temps can swing and be completely normal. You can expect anywhere from 160-225F, depending on car mods, driving demands (street vs track) and ambient temperature. Typically when I hear someone with a random heating up while sitting idle I tend to think fans stopped working. Also if you get air in coolant system you can get incorrect readings. Especially with how easy it is on our cars I would do a compression check after hitting 11 bars as that's 235F range. Some people get lucky on overheating and have no issues.

 

The "overly large normal range" is just fine. 4°F increments from 160° to 180°F any use? Just need to know if the temp is good to go and the OE gauge does that just fine as do the so-called idiot lights in most cars. The "gauge" in one of my former cars had a needle that stayed right in the center of the scale once the car warmed up. Determined it wasn't a gauge at all it just had 3 positions for the needle: cold, normal, hot. But it looked like a linear gauge. (This gauge will not work in a DBW car.)

-- Chuck

 

Just buy an OEM rad cap and you will be fine and feel better.