Head temperature and oil temperature are different things

It only hit me the other day – just because your oil temperature is OK does not mean your cylinder head temperature is. (maybe you already knew this, perhaps I’m a bit slow)

It’s winter here in Sydney, and last week I rode into the city on a miserable rainy day. I kept an eye on my oil temperature (measured at the sump) – it was staying around 80°C, mainly because water was splashing on the oil cooler.

I didn’t have my fans on. I thought I didn’t need them because the engine oil was staying so cool.

But I was wrong! After sitting in traffic for a little while, my engine went into parade mode. That means the cylinder head was in danger of overheating – around 350°C.

I immediately switched the fans on and was out of parade mode by the next set of traffic lights. But a good lesson – run the fans in traffic even if everything else is cool.