So I have a 96 Tacoma 4x4 with a 99 3.4 in it few weeks ago it got hot so I replaced thermostat, water pump, timing belt, all tensioner pulleys an all that and after all that the temp gauge still goes all the way to just before the red within 3-5 minutes regardless of outside temp. Before I changed water pump the heat would get hot and then cold hot then cold, after k changed it the heat stays nice and hot? Is the temp gauge bad or the sender unit?

 

Did you bleed the system and get all the air out?

 

Nope I didnt, isn't that what the jiggle valve on the t stat is supposed to do? Anyway how do you bleed the system?

 

You need to measure the temperature independently of everything else. You need to measure it with something reliable. The gauge on the panel is not for troubleshooting gauge problems!

 

I have an infared temp gun, is that a reliable enough way? Or are you referring to a different method?

 

That's your problem. Jiggle valve HELPS, it doesn't do it all by itself.

1. Heater on HIGH (front and rear, if so equipped).
2. Park facing up hill on mild grade or put front wheels on a curb.
3. Fill radiator and fill reservoir to MAX.
3. Leave rad cap off.
4. Start engine and allow engine to heat until thermostat opens--you will see coolant start to circulate in rad.
5. You will see bubbles escape from rad. After several minutes, bubbles will stop coming out.
6. Turn off engine, allow to cool.
7. Fill rad, replace cap.
8. Fill reservoir to MAX.
9. Take for a drive of at least 20 minutes. Allow to cool. Check coolant in reservoir and add coolant to MAX if needed. Or just use as normal and check the next morning when engine is cool.

 

So I did this and nothing happened, and temp gauge did its normal thing, bad radiator? Head gaskets?

 

What is happening in the radiator?? Do you have big areas with no flow that are blocked??

Is the coolant getting hot ?? Just the gauge?

I never had the issues with the 3.4 like the 22REC for air pockets.

Did you get the thermostat in upside down?? Easy to do

Just how hot did it get??

Why did it get Hot??

 

I have no idea why it got hot, that's what I'm trying to figure out, the gauge was holding right under the red area, didn't go into the red at all, I put the jiggle valve at 6 o clock, lower rad hose is warm and top hose is hot, top of rad hot also, I followed the steps above for burping the radiator and no bubbles ever came out, I let it sit there and run for 20 minutes and nothing happened

 

So no idea what I did wrong the first time but I tried burping the radiator again and a lot of bubbles came out for about 5 minutes but the dumb gauge is still going to the same mark, previous owner did some wiring behind the dash any chance the needle got messed with and that's what this problem is?

 

I would recommend a live scanner or ScanGuage that can poll temp from the ECU. Different sensor than the gauge and more accurate than gauge or IR thermometer.