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Overheating,... sometimes

2003 Baja with over 90,000 miles.

Driving around town does not seem to cause any problems but after driving highway speeds (55-70mph) when stopped at a light the engine temp rises to near overheating. After I start moving the temp returns to normal and seems to be fine until the next time I hit the high way speeds.

Those symptoms usually indicate a fan or air-flow problem. Is/are the fan(s) running?

I think so… I thought I heard it running but have not actually looked. I will have to do that. Nice suggestion.

That does sound like a fan malfuntioning or an air obstruction. If the fan is not running when the engine is hot, check fuses and relays before replacing the fan itself.

OK… to further the mystery…

It has been running perfectly normal the last few days. No overheating of any kind,(BTW, the fan does run) until this afternoon… Highway was fine, most of the city driving fine until 20 minutes or so after I left the highway the temp ramped up. It was just a minute before I was going to stop so I parked, shut off the car and when I restarted minutes later, the temp was normal and remained so the rest of the way home.

The coolant system capacity is under performing. It could be a simple low coolant, a flush and new coolant, low pressure in the system, bad radiator cap, bad thermostat, partially blocked or clogged or deteriorated radiator, then moving your way up the $ ladder to head gasket etc. Some gauges have dampers built in so you may wish not to trust it. Have a qualified mechanic figure out the problem for you, unless you want suggestions for diy parts replacement.

Thanks for the tips. Think I’ll get it in soon for a flush and fill and while they are at it they can give it a once over. Due for a whole once over anyway.

Thanks to all!