overheatng

My truck temp. gauge goes to overheating within two minutes of start up. I didn't know what was up so I changed the thermostat. Same problem. So I took out the thermostat and the gauge still goes hot at idle with in 2 minutes of start up. Any ideas?

 

could be your radiator is clogged up and or fans not working properly..

 

Air in the system? Fans? Water pump?

 

I thought the water pump might be the next thing to look at, but it was just replaced 6000 miles ago. Is there any way I can test the water pump to see if that is the problem. Fan is working pushing a lot of air. Is there more than one fan? Water flows freely thru the radiator when I flushed it. To me it doesn't seem that the engine would get that hot in two minutes at idle, to push gauge to max hot. Could gauge be wrong?

 

Can you give us some background on the truck? How many miles are on it? What maintenance or repairs have been done and at what mileage were they done? Were OEM parts used or aftermarket? Etc.

 

It is a one owner truck bought new. It now has 200,000 miles. I always had the Toyota dealership do all the work. New frame, 2 timing belts, first at 115,000, second at 194,000 and replaced the water pump at the same time. Regular maintenance, oil, plugs etc. that is about it. The truck has had no problems or issues. Not bad for 200K. It is just the temp gauge pegs out max hot at idle in 2 minutes, even with out a thermostat installed.

 

If the thermostat is out, and it still shoots to hot on the gauge that quickly, then something is blocking coolant from flowing or something is sending a bad signal to the gauge. Wait, or you have tons of air trapped in the cooling system. You have verified the coolant system is full? Have you tried back flushing your radiator or even better, the whole system(clear out potential blockage)?

 

Thanks, yeah I flushed the radiator, then took off top hose and poured water into the engine , it immediately came out top of radiator. Seemed like system is full.

 

How about more specifically a back flush? It's late, I dont feel like explaining it, sorry man. There are plenty of good explanations on the internets. You've also tried running it with temp dial moved all the way to hot as well and hot air blew out of the vents? Not saying that fixes it, just looking for more data is all

 

I just backed flushed the radiator. Took off top hose and ran water thru engine. Seems to be no blockage. After starting temp. gauge pegs out at max. hot in 2 minutes. Everything is cool to the touch. Could it be the temp. sensor sending a false message? Warm air does flow out vents.

 

To rule out the water pump, run the engine with the top hose disconnected. Pull the Anti freeze out and put in regular water without the thermostat. If it does not throw water out the top of the radiator, the water pump is toast. If it does, go get another sensor. Yeah, it's messy.

 

the hoses cool to the touch too? does it start blowing coolant into the overflow tank? If not then Id suspect the temp sensor.

 

If everything is cool to the touch and the gauge reads hot, then definitely something going on with the sensor or the wiring. Good work, you've at least confirmed you're not running hot

 

Thanks guys!!! I pulled the top hose and water did come out after starting the engine. So water pump is good! I will order a temp sensor next. Guess it will be self explanatory as to where it goes.... but can anyone give me a clue?

ADDED I just looked up sensors on-line.
Choices are coolant temp sensor, temp sensor, engine temp sensor

I would rather not buy all three any ideas???

 

http://www.customtacos.com/forum/127-1995-5-2004/155936-2rz-engine-coolant-temperature-sensor.html

You never said what engine ya had. So I gave ya this link just fer grins.

 

Thanks guys for all the help. I work with wood so any help is great. I have a 3400cc EFI 5 speed manual. 5VZ-FE engine. I will look for other threads that have coolant sensors locations. Again thanks for all the help couldn't have got this far without all help

EDIT for the gauge on the dash do need to replace the "water temp sensor"??
Not the "coolant temp sensor"?

 

The temperature sensors can be tested with an ohmmeter. You compare the resistance versus temperature to the chart in the repair manual. (Download the Toyota repair manual pdf from the sticky thread link.) Why waste money throwing parts at it if you're not sure they are bad?

You can hook up a scan gauge to the OBD port and read the temperature in real time as the engine runs. This will show the temperature based on the sensor the computer uses. The instrument cluster temperature gauge uses the other sensor. You can compare the two readings to see if they match.

The Toyota repair manual should outline how to diagnoses a problem with the gauge to see if it's a problem with the sensor, gauge or wiring.