Drilling hole in the thermostat

05 Jun 2004 Drilling hole in the thermostat

Do we need to drill a hole in the thermostsat for the original 2.5 engine?

If so, what size?

Yes, all engines could benefit from a 0.25 hole in the thermostat in order to add more hot fluid to it’s opening mechanism on it’s top side and thereby even out the amount of cooling taking place between the right and left radiator.

The procedure is:

1) Drain fluid from the engine through the drain at the bottom of the thermostat housing located on bottom of the engine on the opposite side from the oil filter.

2) Remove the thermostat housing and take out the thermostat.

3) Remove the sealing ring from the thermostat use diagonals to cut away the jiggle pin through the outer ring. Hold the thermostat with two Wise Grip pliers and drill the now available jiggle pin hole u to 1/4″ Be VERY careful, the thermostat edge is sharp.

4) Deburr the hole and reinstall the sealing ring.

5) Install the thermostat with the bulb and spring up into the engine.

6) Install the thermostat housing and refill the coolant.

7) Start the engine and feel to be sure the left and right radiators warm equally fast.

Jan