stock temp gauge falls when at WOT for longer then few seconds

[jayc-glanza17]

two nights this week after seeing the mrs, on the way back home, i gave it the beans from slip road to a road.. so 2nd,3rd and WOT and very high revs...

on doing this i noticed my stock temp gauge fell down..

why would the gauge go down whilst at WOT, and very high revs???

yet if u drive it normally the gauge does not move stays where it should, very odd...

btw im forged 4e for two years now, and havent got an aftermarket water temp gauge

 

[weeJohn]

If its not a gauge or sensor fault, it could be the rad is cooling faster than the stat has a chance to close.

 

[jayc-glanza17]

forgot to add im running a full length 40mm thick ally radiator...

but warms up fine according to gauge..

 

[weeJohn]

Put a piece of cardboard in front of half of it and see if it does it.

 

[jayc-glanza17]

other then the rad cooling too much for thermostat..
what else could be the issue?? because everythings connected and working..

just want to start doing a process of elimination

 

[AdamB]

Sometimes depending on air temp and how well designed your front bumper is you can create the correct turbulence to dissipate heat even further.
Have you played with anything since you've noticed this? Might be worth checking the stat is working correctly.

 

[jayc-glanza17]

only thing thats change adam.. is cruise bonnet(been on for few months) but didnt look at temp gauge as intently...
also battery relocated to boot..

i will check the thermostat, btw the heaters blow hot, but only once car is warming up, but they dont cool down as the gauge falls down on WOT..