New timing belt water pump thermostat idler pullies the whole 9 yards.Truck hits 205 and then gose back to 198.Before it rarely hit 200 in summer.New toyota, coolant also.Runs and starts great.88000 3.4 4x4.All factory parts . could I have gotten defective thermostat.Curious.

 

Contrary to most, the 3.4 5VZ-FE likes the thermostat with the jiggle valve at 6 o'clock. Did you install it the other way?

 

Yep.12 oclock.So it makes that big a difference.

 

Not a big difference, but what you see is about right. I had the same results when I installed mine. At 12:00 the temperature pointer indicated about one pointer's width warmer than usual. I changed it back to 6:00 and the reading returned to its original point.

 

The gauge on dash reads about normal but scan gauge says 204 to 207 and sometimes back to 198 where it rode before all the time.I have another new thermostat.may put it in and put hole at bottom just fir kicks

 

The thermo valve being up versus down is easily an 6-10 degree difference depending on grade as well. Flip it and you will be just as surprised as I was.