Need help! Gas engine overheating. Cannot resolve.

That hose loop and that second temperature sensor are for the exhaust heat recirculation system, which I do not think is used in all market regions.



I wonder if it is present in Lithuania. Does the exhaust arrangement under the car look like this (note the two coolant hoses)?

 

No, my excaust system is very simple, just catalytic converter ant two pcs lambda. Ok thanks for the info, that's mean in the EU we don't have this exhaust system.

 

edit

 

How to do EGR system cleaning?

 

@Sergey K. Did you ever find out the issues and have a fix? I am having same issues with my 2011 Prius

 

Did you fix the issue or find out what was wrong? I am having same issues. TIA

 

Check post #35

Posted via the PriusChat mobile app.

 

Post #35 may have some red herrings in it. Replacing the faulty water pump was certainly important in solving that problem.

There are some rituals being circulated that make filling and burping the cooling system a lot more complicated than what the repair manual says to do, and what's in the repair manual has reliably worked for me.

 

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Hi @Sergey K and others: Very enlightening discussion! My situation maybe slightly similar, but not quite. In my 2013 Lexus CT200h, it rattles during idle, coolant temperature becomes much higher in 15 min, and coolant begins to overflow out of small opening underneath reservoir cap. I have written down some details below. Please give me some ideas on what to do next. Thank you!

Already performed below on my 2013 Lexus CT200h (~157000 Miles):
1) Headgasket job
2) Valve
3) Fuel Injectors replacement
4) Spark plug/coil replacement
5) Egr, Intake Manifold cleaned
6) No OBD codes, no code for water pump or anything else hence did not replace it
7) Coolant does not seem to be leaking into cylinders
8) Engine oil is clean
Issues post all above job: Below happens while starting car in Maintenance Mode
1) Rattling during idle
2) Noticed Coolant temperature went to 235 deg F after idling for about 15 minutes
3) Then Coolant overflows from reservoir
4) If I press accelerator, engine sound is normal
Questions:
1) I may have connected incorrect hoses. Could not find documentation/drawing anywhere. Please correct me:
(a) Currently firewall big hose on top is connected to EHR Pipe Right Opening
(b) Currently firewall big hose on bottom is connected to Engine underneath EGR
(c) EHR Pipe Left (Passenger side) hose is connected to EGR Cooler
(d) EHR Pipe bottom ("T") hose is connected to EGR
2) What could be the issue? I have done everything I could think of and have spent lots of time. I do not think engine is knocking and coolant does not seem to be leaking into cylinders. Engine oil is clean. This has been extremely frustrating, do not know what to do next? Please help! Thank you so much in advance!

 

Does it overheat when driving?

Do you see the coolant flowing in the engine coolant reservoir? It should around 190f and may require a led light on the plastic to see flow.

Does the temperature alert light come on?

Do the radiator fans come on while it is overheating in maintenance mode??

Normally in maintenance mode you should have the ac off.

Normally a second hg problem will not cause an overheat assuming the coolant is full but could cause the rattling.

Assuming no head gasket sealer was ever used, I would certainly remove and inspect the engine water pump and thermostat.

The big radiator to engine hoses are what keep the engine cool combined with the water pump and thermostat.. The radiator must flow and the radiator fans must operate when the car is not moving. The rest of the coolant hoses could be blocked without overheating the engine.

 

Don't reply inside quotes. If you want to fix it you need to troubleshoot.

You need to answer the questions to narrow it down. Since you have not driven it since the hg you could easily have a timing chain installation issue. Very common with diy. You have to follow the book which says rotate backward to trip the tensioner to avoid timing off.

Does it overheat when driving?

>>> I am too afraid to drive, have not driven. The rattling sound gets much louder when Hybrid battery charges. I wonder if the rattling sound and temperature rising above 235 could possibly be air trapped? Not sure how to check if there is air trapped?

It's not air trapped.

Do you see the coolant flowing in the engine coolant reservoir? It should around 190f and may require a led light on the plastic to see flow.

>>> I did not pay attention. I will next time I start engine in Maint mode. I did notice coolant boiling in the reservoir and overflowing from the opening underneath the can when temperature was above 235.

You have to check this which partially confirms the water pump is flowing.

Does the temperature alert light come on?

>>> Yes, light came on when temp went above 235

Normally it comes on at 248f unless you have a water pump code, many of which you can't read with a cheap scan tool.

Do the radiator fans come on while it is overheating in maintenance mode??

>>> I did not pay attention, I will next time and will let you know.

You have to know what is supposed to happen before you have a prayer.

Normally in maintenance mode you should have the ac off.

>>> Couple of times, I did turn on AC. Do you meant do not turn on AC during maint mode?

Exactly what I said. AC off.

Normally a second hg problem will not cause an overheat assuming the coolant is full but could cause the rattling.

>>> I hope this is not HG problem again. After performing HG job, the car has stayed in garage because of all these problems and I am too afraid to drive.

I give it 50/50 the hg job failed.

Assuming no head gasket sealer was ever used, I would certainly remove and inspect the engine water pump and thermostat.

>>> When I did HG job, there was no indication of sealer used in the past. Removing thermostat looks too difficult, but I will try. Don't you think if there are issues with water pump and thermostand there would be some OBD code? There is not a single code currently except for engine rattling/knocking/vibrating violently and coolant overflowing when temp is above 235

No codes on wp failures happens

The big radiator to engine hoses are what keep the engine cool combined with the water pump and thermostat.. The radiator must flow and the radiator fans must operate when the car is not moving. The rest of the coolant hoses could be blocked without overheating the engine.

>>> I am tired of troubleshooting but I will. I think you made very good points. Thanks so much for educating me. Now I am beginning to understand that mechanic job is extremely difficult. I will check everything you pointed out and hopefully will be able to find the culprit. Thank you so much again!

I get it. It's not easy being cheesy. Get the hg instructions and see if you messed it up. If you did, start over. You have to warm it up to check engine cooling. Drive it for a mile because many first starts after timing work will rattle for a short time.

 

Hi @rjparker:

Thanks so much again for helping me. I will check everything you suggested and will write again. It may be another couple weeks before I will get chance to spend time on this again. I apologize, I liked - I did drive it for a couple miles after head gasket job was completed, but I drove it in Maint mode. Was too afraid that hybrid battery would die on me. During those two miles drive, I did not even know that I was supposed to be checking for overheating nor I knew how to check temperature. I do not remember if temperature light came on dash during that drive. Next time I drive I will pay attention.

Also, did you watch the video I posted?

So, from everything I read it looks like below are the possibilities and things to check:
1) Faulty water pump
2) Faulty thermostat
3) Bad head gasket job
4) Make sure radiator fans comes on
5) Make sure coolant is flowing into reservoir
6) After reading this blog, I felt like there may be air pockets that could be causing the overheating. Not sure if I should drain coolant, refill/bleed/burp?

Thanks so much again!

 

The gen3 hybrids have very little problem with air pockets.

 

@rjparker : Thank you for clarifying. I did not know that!

 

In the first gen3 2010 models there was an air bleed at a T connected to a hose going to the exhaust heat recirc system. In 2011 up the access was removed. I have changed coolant at least ten times and simply refill and run in maintenance mode for a few minutes with the reservoir cap off to relieve air as it circulates. The heater flows at all times, there is no shutoff valve.

Just to be clear, the video you attached above is someone else's CT200, not yours? But yours operates the same now? Eg runs smooth at first for a minute, stumbles and starts running with a severe rattle? In the video stepping on the gas smooths things out. The note below the video said changing the water pump fixed his issue.

Further for clarity, you don't get misfire codes?

Finally were the plugs, coils and injectors you replaced oem Toyota? Aftermarket injectors are often issues.

Regardless, engine cooling problems remain a huge issue and most commonly are water pump related. Typically an unplugged water pump or wiring/fuse would code but we don't know what code reader you have.

 

That's the same thing I do, except I follow the repair manual instructions and have the cap on for that. It allows the system to come to operating pressure, roughly two atmospheres, so all air bubbles become half the size and may travel more readily through the system.

The bubbles end up in the degas bottle (reservoir), which is made for that purpose, and has enough headspace designed in above the FULL line for all the air that circulates back to it.

If you started with the system filled to B, put the cap on, ran the engine several minutes past reaching thermostat operating temp, then shut it down and let it fully cool, you should be able to check the level and see that just enough coolant and air have traded places to drop the level right down to the FULL line.

It's almost like the engineers knew how much that would need to be.

 

Another occasional issue is a stuck open egr valve causing roughness at idle. The egr is designed to block egr gasses at idle and wide open throttle. At cruising rpms the engine can take the egr gas which is intended to reduce emissions.

A simple egr flow blocking test can diagnose a stuck valve as can a Techstream egr valve active test.

Egr blocking test
Starting at egr test

At about 10:15 in the video he starts talking about the egr valve letting "air" into the intake manifold. He means exhaust gasses.

 

Vapor lock?