'01 TT with 57k miles on it. My coolant temp gage started acting up recently. As usual, I always let the car come up to operating temperature (180°) before I start doing WOT runs. The car was at 180° after about 5 minutes of driving, I did a 2nd gear WOT almost to redline and I looked at my coolant and it was well under 180° as if it cooled off or something. Then after about 2 minutes of driving it returned to 180°. It was almost like I had 2 warm up periods. I wasn't too concerned since it was reading cooler not hotter, but still, it seems weird. Anyone else experience something like this? Faulty gage or temp sensor, maybe the thermostat? Thanks in advance!

 

Did you check the coolant level? Maybe low...

 

More than likely the full coolant system ( which is a lot) wasn't up to temp. When you did a WOT the engine gained a lot of heat, thermostat opened and incomes a cold slug of water, drops the engine temp right down until it warms back up and your gauge returns to normal.
5 minutes is not enought time to warm one of these cars to full operating temp. Don't forget there is an oil tank with loads of oil that you have to warm up as well. You just did a wot run too soon IMO.

 

Sunnyside, that's what I was thinking. Thermostat opened all the way and cooled it down quickly. The funny thing is that the temperature never spiked over 180° it just dropped down from 180°.

Raineycd, Yes the coolant level was full.

Thanks for the responses! I guess it just takes longer than the coolant temp gage indicates for everything to warm up.