Hello

 

for past days i noticed my temprature gauge goes down while i am driwing and and comes back on 90

 

i m nearly 200000 miles, its never heppen before, 

 

and car is loosing cooling water aswell.

 

what it could be. 

 

Thanks 

Might be the thermostat is starting to play up.   Coolant wise it could be leaking from any where !

I'd be finding where the coolant is going! Perhaps the temperature gauge is moving due to air getting into the system?

The fast movement of the temp gauge is due to air or gas at the temperature sender.

If you can't find any evidence of where the water is going, I would start to suspect a failing head gasket is over-pressurising the cooling system and forcing coolant out past the pressure relief valve in the coolant bottle cap.