Need help! Gas engine overheating. Cannot resolve.

In the Repair Manual, I'm not seeing anything regarding testing the Water Pump with Techstream, could only find how to replace it. Maybe missing something.

 

Is there anything in the Repair Manual about the egr cooler clogging?
All the work that is being done with the cooling system could be a waste of time, even flushing
out the radiator and related items, if the coolant pump is defective.
Is there a way to test it correctly without using techstream?

There bearing could be trying to seize when it gets hot, or resistance brakes down and it's getting
too much amperage or voltage. Without proper testing, how would you know?

Have the small passage ways in the head been cleaned out? What about the block?
Is there goop on the sensor causing inaccurate readings? Hopefully, using that coolant cleaning
stuff cleaned it all out. Maybe the cooling sensor is bad?

 

There is a troubleshooting section. I honestly haven't "cracked that book". I mainly consulted just the removal/install section, for torque values, and the pictures. @ChapmanF is really up on how the EGR valve stepper motor works. I'll attach both EGR doc's.

 

There is a test procedure (repeated identically at several places in the manual) that involves using Techstream to tell the valve to open different amounts and confirm that the effects on the engine are seen. If that happens, it's a pretty positive confirmation that the gases flow. If it doesn't (or if the valve has to be opened way farther than expected), then something is clogged. It won't tell you whether the something is the cooler or elsewhere, but it's easy to do to get a quick idea whether you want to get tools out and look further.

 

I guess I should start looking over tech stream to see what it can do.
Beside turning on the idiot reverse beep!
Thanks!

 

210 F is not "hot".
With a pressurized system, some vehicles run there all the time.

When you had the water pump out, did you check that the impeller was tight on the shaft ?
And that there are no "vanes" missing ??

 

Hi there. I have a similar problem in my Prius 2012 PHV. It's giving me over heating problem at highway. I was driving the car at 120 kph. Later when I reduced the speed, the overheating light was also blinking at nearly 80kph. I also noticed the burnt oil during oil change. I cant find any error codes except steering angle sensor which was already changed earlier. Any suggestions to my problem will be highly appreciated.
Thanks
Faraz

 

The "error code" is the overheat light.
You need to have a shop look at it.....before you burn up the engine completely.

Unless the radiator is all plugged up with insects and leaves.......the most likely culprit probably is the water pump.
But there are other things too.

 

Get ready for a new engine!

 

Water pump is still oscillating between 0 rpms and 6000+ rpms, and car is overheating. I've tried purging the air almost ad infinitum, and have accepted the fact that it's probably not that. I bought a brand new water pump, specifically for the 4th gen engine (which I swapped into my 3rd gen car a few months ago), and have installed it. Will update whether or not that has any effect. I spun the circular magnet in the water pump that I took out and it still feels good (not lose, but not stuck). I even removed the tiny o-ring and washer, and took out the magnet entirely and there were no visible signs of damage.

Out of curiosity, I tested my water pump plug today with a multimeter (with car in ready mode), and the two bottom right pins (the thicker red wire and thinner green wire), tested at 12.1 volts. As for continuity and resistance, I am unsure how to go about this. Wouldn't I have to remove the connector from the ECM and find the precise wire in order to test resistance properly? I tried placing the one prode of the multimeter to both top pins of the connector (one by one) and the other to the engine block - though I am (1) assuming this is an ineffective way of testing resistance, and (2) assuming that perhaps the car should be off and no voltage supplied. For what it's worth, there is continuity on the top left pin (thicker red wire), and 4.73 ohms of resistance (20k setting) on the top right pin (thinner blue wire). Although I am highly suspecting these values to be useless (except the voltage tests) until I can figure out a better way of testing continuity and resistance. Honestly, I need to go ahead and buy a 3rd gen Haynes manual...

Additionally, when I tested resistance on the pins on the water pump itself, it started low and eventually reached 10.9 ohms (20k setting). I tested a brand new, unused water pump (which I just installed) and it measured around 10 ohms. This may not be important, but I'll include it anyway... also, I may be using the wrong ohm setting. I'm not sure.

The main question here is: what is the ideal voltage supplied to the water pump supposed to be in ready mode? Is 12.1 volts too high?

 

Replaced with brand new water pump (that matches VIN number). Problem still persists.... going to replace thermostat... again... for the third time... During air bleed process, temperatures exceeded 215 with no indication that thermostat opened... it was a brand new thermostat - not sure why it's not working. Is it that these aftermarket thermostats are just crap? It was an AISIN THT-017. According to my Amazon records I've purchased this item 3 times (the first time was for my old engine). What gives??

 

Are you certain you put it in the correct way?
If it has one of the ball checks it needs to be at the top.

 

I did. So I test drove it and it drove slightly better than before the water pump swap. Instead of reaching 240 fahrenheit at 55 mph, it reached up to 220 fahreinheit at 55 mph. That is some improvement (though the outside temperature is 80 degrees rather than 95, if that makes a difference). At this point I don't know what it could be. I guess I could take Ragingfit's suggestion of drilling small holes in the thermostat to allow some constant flow. I might take it up to Toyota and just let them do their professional, pressurized air bleed process. There's only so many times a water pump and thermostat can be replaced. I guess my biggest complaint is: why in the hell did Toyota remove the radiator cap in the 3rd gen??? To me, that seems absolutely stupid.

 

Is the radiator and/or condenser dirty? Blocking air flow?
And the fans blowing the correct way?
The thermostat has a little brass pin thingy, with a small ball bearing in it, that's all you need.

It doesn't need a radiator cap. The overflow tank has it.

I learned a long time ago to fill SLOWLY, a little at a time, squeezing the large radiator hoses as I fill.
Some cars have a bleeder valve somewhere around the egr cooler you can open.

There may be a blockage in the radiator, or somewhere in the system. You didn't ever put stop leak in it???
I don't remember if you have techstream or not, but with that you can test the water pump.

You may have an electrical problem that is not telling the water pump to spin fast enough, or too fast, and
damaging the motor.

 

Perfectly acceptable. A proper mix of coolant under pressure won't boil until about 230.
During that test trip, did you notice any indication of "overheating" ?

Notes: Most thermostats already HAVE small holes.
And if there is no radiator cap, what holds (and releases) the internal pressure ??
Maybe there is a "radiator cap" but it is on the overflow bottle ??

 

2010~2011 have the bleeder valve, on a black-plastic coolant hose junction just above EGR. There's a white, knurled cap on it that you partially unscrew, which allows air to bleed through a spigot. The spigot is designed I think so you can push a tube on, mainly to catch spill.

I drained 2 liters when doing the EGR clean (to avoid spillage when removing EGR cooler). When pouring it back into the reservoir I opened that bleeder valve and could feel air coming out as I poured. I also burped hoses a little as I poured, as you mentioned. Hopefully helps.

For 2012 onward, Toyota has eliminated the bleeder valve (why the hell would they do that...). Still it seems to me if you pull off one of the hoses right there, you can achieve the same air bleed?

 

Mine is a 2012 - I've started removing the temperature sensor posterior to (and slightly above) the EGR cooler, and fill until it pours over. You may have been the one to suggest this several months back, though I can't remember. That eliminates most air for me. Which is why I would have thought it would be doing better than 220 degrees F. I keep hearing people say 190-195 degrees and I'm a bit jealous.

 

Both radiator fans blow correctly, as far as I can tell. I've never put stop leak in it. I don't have techstream - something I've put off for a good long time and is starting to get ridiculous . I do get a P148F (water pump overrevolution) code occasionally. With the previous water pump I would mostly get it while purging for air, with the reservoir cap off, though I did get it a time or two from driving past temps of 230 degrees F. With the brand new water pump I've gotten that code once during the air purge process, when water pump RPMs reached 6000. The previous water pump would routinely reach 6000 rpms and drop off to 0 while driving. This brand new water pump seems to reach anywhere from 4500 to 5000 (while driving at temps of 210-215)- I haven't noticed it dropping to 0 yet, but I need to keep test driving it. It could be the previous water pump was faulty, as it came from the 2017 engine that I recently installed, which was in a wrecked car (the car flipped at about 60k miles). Note: the brand new water pump I bought matches the 2017 engine, not the 2012 car. I've wondered if perhaps the ECM is faulty, or if I should consider buying a 4th gen ECM?

 

I think you should STOP guessing and shot-gunning money at it.......and take it to a shop for professional help.
Given what you have done already, that might end up being cheaper in the long run.

 

Yeah me too: just throw in the towel and have the dealership sort it. Hopefully they can.