Hi guys,

Lately i repurchased my old MR2 after 3 years of not owning it. It was taken care of very well, but since getting it back I have noticed a confusing issue.

Whenever i drive the car, if its in low speed, stop start traffic, the engine will get to operating temp fairly normally. However, whenever I start to drive at a higher speed or on highways, the temp drops gradually back to zero.

I tried turning the engine off and seeing if it climbs back up after driving on the highway but it seems to be reading the correct temp as it doesn't climb.

Note: its a 97 sw20 bathurst
Any ideas of what could cause this?

Fair chance of a stuck open thermostat.

I had a similar issue, altho it never went right down to zero.  Changed thermostat & all fixed.

Welcome back.  
 
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