My 1990 4 Runner gauge takes a long time to raise to normal. After letting it idle for several minutes and then driving it for 20 miles or so, it still reads below cool when it should read normal. The heater works fine, new thermostat and radiator. Just replaced the head gaskets and the heads and block are clean. I am baffeled by this, by all rights the gauge should at least register something after running that long. Any ideas are welcome as to what might the problem be.

 

May not be a 'problem'. After doing a cooling system flush, radiator clean, painting my radiator with a black heat-dissipating paint (looks awesome), new high-flow water pump, and a high-flow t-stat, mine barely hits 180 degrees with the A/C on full blast in 98 degree summers. Right now, in winter, it runs around 165-170...can't get it higher. Runs like a champ. Yeah, it may affect emission a tiny bit, but it lets me run a bunch more advance without pinging...free horsepower!!

On the flip side, you should check your temperature sending unit...could be just giving a false reading.

 

thanks for the info. A cooler thermostat might help but I believe I have a restriction in the heater pipe under the intake

 

If you have an electric fan, check to see that it isn't running all the time. that would keep the temp down. Also if the thermostat was installed incorrectly (backwards), or the wrong range, it could cause that problem.

 

i should mention,it aint running cool,its running hot,but guage shows normal.

 

do you have the 2 stage or regular tstat? i am assuming a 22re engine? my oem tstat died on me in less than 6 months! jsut replaced it with the 2 stage

 

3.0 . What is a 2 stage?

 

Just two different levels of operation. A partial flow and a full flow operation, depending on temp level.