I was coming across the border from the US to Canada this aft and was in line waiting for about 45 minutes. My engine temperature needle rose until it was just shy of being in the red zone. I couldn't tell if my fan is coming on but I'm just wondering if this is normal behavior for an air cooled engine to run that hot when sitting idling.

FYI, as soon as I got through customs and started driving again, the engine temp immediately started dropping and within about 10 minutes it was back to normal.

 

What was the ambient temp, can't imagine it's that high. I'd guess your fan didn't engage or your oil thermostat went south.
When I idle, like today, in 105 ambient and turn my fan on the temp actually drops (I use a switch not the therm controlled deal) and will stay at 200 or less.

 

It sounds like your oil thermostat

 

If i remember correctly you have a 3.2 in that car. You would have an internal and external thermostat would you not ?
Id be checking them both and adding a switch to that fan for good measure

 

I chased this kind of problem a few years back in my 88. Realized the oil lines going to the right front cooler weren't getting hot. Replaced the external thermostat in the right rear wheel well. Oil flowed to the right front oil cooler evidenced by a very hot supply line and a much cooler return line. Back to normal temps.

A few years later, it started again. Replaced the stock oil cooler fan switch in the right front wheel well with the BMW 99C switch so the oil cooler fan would come on sooner. That worked for a while.

A few years later my temps started rising again and I realized the fan in the right front wheel well oil cooler was broke. Replaced it with an elephant Racing fan and all was well again.

A few years later temps started going north again. Added a switch to control the fan in the right front wheel well so I could turn on the fan manually when the external thermostat opened to get ahead of the heat buildup. That didn't help. Replaced the engine mounted oil cooler thermostat and that did the trick.

Essentially, I've replaced all of the components in the oil cooling system other than the coolers so I should be good for another 25 years, right?

 

thanks for the feedback. My car has only ever almost overheated twice and both times it was from sitting in traffic on a hot summer day. otherwise, my gauge is always at normal. I will have to investigate further.

 

45 minutes is a looong time to idle a 911 motor.