Water temperature gauge reads low

Good morning.

This sounds like the thermostat is stuck open and not closing.

I would replace the thermostat.

Roy

REMOVAL

CAUTION: Do not pry on water thermostat to remove.

1. Drain the cooling system so that the coolant level is below the water thermostat.
2. Remove the coolant outlet housing retaining bolts. Pull the elbow away from the intake manifold sufficiently to provide access to the water thermostat. Remove the water thermostat and gasket.

INSTALLATION

WARNING: Do not stand in line with or near radiator fan blade when engine is running.

WARNING: To prevent incorrect installation of the water thermostat, the water outlet connection casting contains a locking recess into which the water thermostat is turned and locked. Install the water thermostat with the bridge section in the outlet casting. Turn the water thermostat clockwise to lock it in position on the flats cast into the water outlet connection.

1. Clean the coolant water outlet connection. Coat a new gasket with Perfect Seal Sealing Compound B5A-19554-A (ESR-M18PZ-A) or equivalent. Position the gasket on the intake manifold opening.

NOTE: It is critical that the correct water thermostat installation alignment be made to provide coolant flow to heater. Insert and rotate water thermostat to the left or right until it stops in the water outlet connection housing, then visually check for full width of heater outlet tube opening to be visible within the thermostat port in assembly. This port alignment at assembly is required to provide maximum coolant flow to the heater.

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2. Position the coolant water outlet connection against the intake manifold. Install and tighten the retaining bolts to 9-12 Nm (80-106 in lb).
3. Fill the cooling system with the recommended Premium Cooling System Fluid E2FZ-19549-AA (ESE-M97B44-A) or equivalent and water mixture. Check for leaks and proper coolant level after the engine has reached operating temperature.

NOTE: A coolant mixture of 50 percent coolant concentrate and 50 percent water is recommended to maintain best overall performance. To avoid damaging the radiator, the coolant concentrate should not exceed 60 percent.

What temperature thermostat did you use?

Roy

I had the exact same problem with my 2003 Explorer (except I have a 4.6l). The problem was the temperature sender unit. I kept getting codes for coolant temperature running cold, and also, sometimes it would peg the meter like it was overheated. At first I replaced the thermostat. I still had trouble with the gauge so I replaced the temperature sender and that solved the problem.

Jon

As Johnny said, if you have a code for the system such as 128, then it is running cold.

I am not a fan of the thermostats from AutoZone. Just get a good quality one and it has to be a 195 degree. Anything lower and the engine will not heat up enough for fuel mapping.

Roy

I could not agree more! Yes, I used a 195 degree on mine as well. I have had problems with AutoZone stuff as well in the past, especially electronic things.

I use a low temperature failsafe thermostat in my 2002 Blazer for the mail routes that I run. The failsafe will kick in and hold the thermostat open until I open it up and release the metal tabs holding it open. During the winter I just use a regular 195, no problem. In short, get a regular thermostat or open up the housing and release the metal tabs -or- bend the trans back enough that they will not hold it open anymore.

And do not worry Roy, I still reach operating temperature with all of the stop and go. It just takes a little longer and does not go above 195. It would get up closer to 215 or so with a regular 195 thermostat, which is why I go back and forth.