Overheating DSE

So, my DSE as overheated again
I changed the viscous fan (that was obviously in it's way out) and all was fine. Did some highway trips and some short trips, without a problem. This morning I drove some 50km on the highway and doing the same route back it overheated when I was waiting at the tollbooth.
Funny thing is that almost no coolant had leaked out. Once I took the cap off, very slowly, it started pouring out and eventually exploded like a volcano, with lots of bubbles. After watching this I came to the impression that the expansion cap should have release a lot of fluid earlier. Could this mean that my expansion cap is not working correctly and not releasing pressure as it should ?

I'm obviously thinking about HG issues but there's no oil in water and no water in the oil. What should I do to troubleshoot a possible HG/cracked head issue ?

Cheers!

Airlock? Where did you get your replacement viscous fan from? there is a lot of crap about. Install my mod to use the aircon fans for additional emergency cooling.

I was thinking airlock too because when the temperature started to raise I set the HVAC to maximum heat and there was not hot air.
The viscous fan is an OEM replacement, boxed by Allmakes PR2. It even has LR logo on it. That was the first thing I checked when I popped the hood and the viscous fan was very hard to turn, so it was properly "docked".

mcapinha said:

I was thinking airlock too because when the temperature started to raise I set the HVAC to maximum heat and there was not hot air.
The viscous fan is an OEM replacement, boxed by Allmakes PR2. It even has LR logo on it. That was the first thing I checked when I popped the hood and the viscous fan was very hard to turn, so it was properly "docked".

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I would say definately an airlock in that case. I have found it is easier to get the air out with the front of the car raised a few inches plus some vigerous hose squeezing