2000 Tacoma Overheating

So my 2000 Tacoma (3RZ-FE 2.7L) has been running hot, just replaced the thermostat and water pump - still doing the same thing. Real similar to what's described in an old post, (https://www.tacomaworld.com/threads/overheating-problem-help.239514/), but basically the temp gauge starts climbing to about 3/4, then if I crank the heater and drive, it levels out to dead center. Lower hose is cool, upper hose is hot and has pressure - Using a laser thermometer shows about 240 deg. near the outlet of the thermostat housing on the engine, should be around 180 right? Not convinced the radiator is plugged b/c wouldn't that also restrict flow through the heater core, and just blasting the heat wouldn't drop the temp..? Any thoughts?


Thx.

 

Air pocket in the system, fan not spinning properly, clogged radiator, dirty radiator, it could literally be anything. Does the coolant boil over?

 

All of what @ForestRunnerFrank99 are good things to check.

My bet would be air in the system.

Park it on level ground or a slight incline. Let it cool down. Take of the radiator cap and let it run for a bit while watching the coolant level. Fill as needed.

Some people put in heavier fluid in the fan clutches to make them spin at full speed more often to help with cooling efforts too

 

Should also say that if someone put the wrong coolant (or God forbid hose water) in it in the past it could possibly be gummed up/rusted somewhere important. There are lots of small sleeves for the coolant to flow through that could clog without you ever noticing a difference in pressure. Coolant Systems are weird like that.

 

The top of the radiator will be the hottest that is normal it is what has done the work cooling the engine. The thermostat is open or you would not get a reading like that. 3/4 on the gauge is not hot.

 

Is your fan clutch working? Does it stay cool if the truck is moving but start to heat up when it's idling or moving slowly?

 

good point.
for a while I used hose water in my cooling systems (mixed with coolant obviously), but didn't realize until I was older that I should have been putting in distilled water.
Hose water has some nasty shit in it that'll leave deposits all over your cooling system that you do NOT want in there.

 

Learned this the hard way on my '98 4.0 Ford Ranger. Previous owner only filled it with hose water and I stupidly bought the truck. Wouldn't pass smog so I pulled the engine apart and woah and behold all the jackets were about 1/8 the size they should be from the nasty calcium and rust build up in it. Cylinder heads were cracked bad from the overheating. Only cost me $1700 to fix ; that's a lot of money when in High School.

 

I did pretty much the same thing lol. I was in highschool and had to pull the head on my '96 4.0 Explorer for the same reason. Fortunately it wasn't bad though. Just resurfaced the heads and cleaned it all up with new gaskets and passed smog no problem.

 

Haha that's great. I guess it's just a Ford thing...

 

There are three circuits for the coolant to flow:
1. Inside the engine block only - the water pump circulates the coolant inside the engine letting it to warm up fast.
2. Through the radiator (controlled by thermostat) - when coolant is hot enough the thermostat opens allowing some coolant to flow through the radiator. The top of the radiator will be hot, the bottom usually is quite cold.
3. Through the cabin heater - controlled by the temperature setting which opens the valve (in full hot position the valve is fully open allowing to circulate hot coolant through the heater core). It is not recommend to open the heater when truck is cold as the cooling effect will prolong the time the engine will come up to the operating temperature. That little heater core is actually very efficient. When driving in Death Valley (steep uphill on winding roads with 125F outside) and see the engine overheating it is recommend to turn on the heater on the full hot blast (it is not healthy for passengers but good for engine).

So the answer is: yes. When coolant has problem giving out heat through the radiator (plugged, dirty, fan not working), turning cabin heat on full hot and full blast will lower the engine temperature.