Hey guys, I recently put my Z6 back together, and within 30 seconds of starting it the temp gauge spiked up past the red. I thought to myself that there is no way the engine got up to operating temp that quickly, but I went ahead and replaced the thermostat just outta precaution. and despite the replaced part the problem still continues! I've even gone as far as to removing the thermostat completely and the lower radiator hose still wont get hot, and the gauge still spikes within 30 seconds.

What could be causing my issue? I'm drawing a blank and could use some help.