1999 Toyota Van

Engine Cooling problem
1999 Toyota Van 4 cyl Front Wheel Drive Automatic 973500 miles

when my toyota lucida vans traverling it will worm up, the gage will go from normal 2hot but no hot steam, but if I move switch from cool level 2 half way the tempurture will drop back 2 normal, if I keep driving with the gage as ease I can keep driving 400kms with no problem at all I give up, can u please help me with my problem thank u so much.
April 2, 2010.

Has the cooling system been serviced? At that mileage you should be on at least your second thermostat. The t-stat could be partially stuck, not allowing full flow. This is a cheap easy place to start. Also look for any leaks, if the cooling system cant hold pressure it will run hot

Apr 4, 2010.