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This engine is a '96 jdm gsr b18c, converted to obd1, that I swapped into my '90 LS. I've been driving it since January, mostly in cooler weather. 40 to 80 degrees.

A few days ago, it was a 90 degree day. I came off the highway and parked to go into a printing store. It sat there in the sun for half an hour. I had not noticed the temp gauge when I came off the highway, so I don't know if it heated up then, but when I came out of the store, starting it took longer, like the starter was dragging some. Hot engine. After it started everything was fine...normal and I drove home (watching the temp gauge). It's typical that when I stop in front of my garage to unlock the doors the fans come on while I've stopped, but then turn off again before I get the car in the garage, and it did that.

This time I noticed the code 11. It's equipped with Hondata and a US P72, so that code is over heated engine.

I tend to do errands in the morning, so I haven't driven in 90 degrees again, but everything is working normally and I idled the engine long enough to feel hot water in both the cooling hoses.

Anybody ever seen an engine get hot and not do it again? I did replace the thermostat when I swapped the engine.
Is there anything else that could cause this? I'm stumped.

Thanks
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Just for fun make sure the heater works(if hooked up). Did the fans come on when you were idling the car? You can also checked temps on the radiator itself across the core to make sure you have good heat transfer. If you don't have an even temperature change across the radiator core it could be internally clogged. The thermostat could be sticking intermittently(if you install one of those safe thermostats remove it and throw it away). Do you have the correct thermostat in it temperature wise?

 

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The radiator was less than a year old when I did the swap...oem brand, denso. The thermostat was straight from Acura.

The only time I've seen the fans run, is when stopping after the highway, usually when I open my garage door. I idle the car up to half an hour and they didn't run (temp normal), but I've been told by rebuilders, it can take 45 minutes. I've never pulled my car out to idle in real hot temps.

The heater works.

What kind of thermometer to use on the radiator?
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