When I drive first thing in the morning the temperature gauge slowly gets to the regular operating temperature level (a little less than half). When going on the freeway and driving up to or more than 100kmh (63mph), the temperature gauge maxes out. After another 10 minutes or so, the temperature gauge goes back down to the regular operating temperature level. At this point, the temperature gauge maintain at this the regular operating temperature level for the remainder of the trip (I could go up to 130kmh or faster it it would maintain itself).

Does anyone know what the issue is? I've checked coolant levels but it seems fine. Could it be air inside the system?

Thanks in advance,

 

Could be air trapped in the system. Or thermostat starting to stick closed.

 

uhhh so you kept driving it even after the guage was maxed out for 10 minutes? Maybe the sender unit is bad? Does it actually overheat and boil over?

 

highly advisable not to drive the car when the temp raised like that at all.

you might have a thermostat issue. try replacing that.

you should probably inspect for damages from driving on overheated engine...coolant system pressure test, compression/leakdown test.

 

When I pull over to on the side of the freeway to look for or smell smoke, didnt see any so I thought maybe it wasn't actually overheated. When the temperature gauge eventually drops from max down to normal operating level, it drops relatively quickly as well (30 to 60 seconds) and then it just maintains itself from that time onward.

 

First thing in the morning I would open the radiator cap to verify the radiator is full of coolant. Also verify the reservoir has coolant. If that checks out, try turning on the heat when the temperature is reading hot or overheating. If there's no heat or little heat then it's a good sign of air pockets in the system.

If you have good heat then next step is to check the upper and lower radiator hoses. If the upper hose is hot and the lower hose is cold then I would lean towards a faulty thermostat. Let us know what you find.

 

Did the following last night (https://www.s2ki.com/forums/s2000-un...eed-1067218/); roughly 4 to 5 times. Topped off more coolant this morning. Seems to be fine now; will monitor more over next couple of days or so.

I think my coolant level may have been a little low.

 

Keep a close eye on it. Coolant system shouldn't have any air introduced to it since it's a sealed system. Might have a slightly cracked hose somewhere. Engine oil level and color look fine right?

 

Yea the engine oil, etc. looks fine.

I park the car 8 to 9 months of the year. Could this be what caused the issue?

 

Or he let his overflow reservoir run dry.