Ok...Whats to hot???

[9240sx]

I search around and cant find a real answer...So whats the best water temp to have my car at.???.And today on the highway i hit 200f for about 15 seconds...Is that overheating or what?-Thanks,

[doridori23]

200 is hot but not too hot. Ideally you should be around 180-190. Water will not boil under pressure until 220-230 at the sensor (remember that the water is hottest at the cylinder sleeves/liners and temp is measures AFTER the radiator @ the water pump)

[carbully]

I don't know about Nissan, but General Motors does not even fire up the radiator fans on their cars until 235 deg F. Short stints of up to like 245 are not a real big deal. Ideally, though, you want the temp right around where the T-stat opens which is probably like 195 deg F.

[carbully]

Oh, and a 50/50 mix of coolant and water under 14psi will not boil until over 250 deg F.

[9240sx]

So its ok if i hit 200f? The car pretty much stays between 170-185ish...Im not sure why it was on 200f...it was odd because i was watching it like a hawk when it was on 200f.It was there for about 10-15sec..and then it just dropped to 190f in like one second? I was thinking maybe i have air in my system and the temp sensor hit a air bubble..I pulled over and set my fans alittle lower..And the engine was not hot at all..I could touch the valve cover all day and the intake manifold too...even my hotpipe wasnt hot at all..

[carbully]

Yeah, you were fine. Remember that as the t-stat opens up it moves pretty slowly, so it is normal to see a slight temp spike before it levels off. A new t-stat might open slightly sooner, but 200 deg coolant temp is nothing to worry about.