Fan operation.

No one mentioned that the radiator cap also prevents the water boiling until a certain temperature depending on the presssure setting, so if it is leaking the water will boil sooner.
 
No one mentioned that the radiator cap also prevents the water boiling until a certain temperature depending on the presssure setting, so if it is leaking the water will boil sooner.

There was no apparent leak, but it must not have been 100% sealed
 
No one mentioned that the radiator cap also prevents the water boiling until a certain temperature depending on the presssure setting, so if it is leaking the water will boil sooner.

That's a good point Doc, I didn't think/remember that wee bit of knowledge.