I have been avoiding highway use, but had no choice today. While cruising at 55 mph on a warm 80 degree day there was a loud fan like noise that nearly made me jump out of my seat. It had no effect on speed or power, but it was a sound like when you step on the gas and the trans shifts, but obviously that wasn't the case. The noise kicked in for about 45 seconds or so then kicked off. Temp was pretty constant at about 210 on the gauge. It did this several times over a 10 mile drive. Is this normal? or does any idea have any idea? It is a m998 with a GEP 6.5