This thread is getting pretty long by now. I need to read it over again.

So you have replaced the radiator cap OEM? I don't trust Chinese brand for something like this. By what you describe my assumption is the cap is not holding pressure.

It has been mentioned multiple times. Does the water pump have any play on the pulley wity serpentine belt off?

Other than that I got nothing. Besides how many times it has been over heated.

 

I'll check the water pump tomorrow. If the cap wasn't holding pressure wouldn't I see coolant alll around the cap???

 

Just re-read your other post about the coolant t reservoir cap. Mine doesn't have that tab. It looks like this..





No play from what I can tell with the water pump. I rented a cooling system pressure test kit from autozone.

There were two adapters for Toyota. I don't know which was the right one so I tried both. I pumped to 15psi and The shorter one lost all pressure. The taller one didn't lose any.





​​​​​And this is my radiator cap.





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That cap is not the OEM style. Are you in the states?

Flip the cap, and post a picture.

As for you system if the radiator cap is more than 5 yrs l'd replace it. You also have some other things going on on the water neck. See photo below. In all it seems the reservoir cap could also be a culprit.

Wet spot on the clamp red arrow.

 

Yes I'm in Florida. It is not OEM. This is it here

Is the positioning of the reservoir cap okay? Mine didn't have the tab you were referring to so I couldn't follow the instructions on the other thread when you said to point the tab at the radiator.

Are you referring to the dry white spots on the hose?? That's from dried coolant. Those white spots are all over the place. On hoses, parts below like the oil filter cap and everything surrounding it, plastic covering of the radiator fans, etc.

 

I'm asking the picture of the reservoir cap you have installed now. It's not what was originally installed on the car. Where did it come from? Also is the other side broken, or is it like that?

You need to set it up correctly if possible for now. If not you need to get the OEM one asap. Otherwise you'll never make progress on this overheating issue.

See picture below. You want the pick up side to be sealed to radiator cap neck. The reservoir cap should have one side that does this. If you flup the cap the vent will just have a hole.

Again flip the cap, and find this out. If it's possible then do it as the Picasso sketch below.

Once the engine cools down it will pull coolant from the reservoir each time. Hence the long tube on the reservoir cap. So it's always submerged in coolant. Now if the hoses are switched backwards. When the engine pulls coolant it will just be sucking in air if the hose from the water neck is tied to the vent on the reservoir cap.

There is a cold and hot line on the reservoir tank. Its best to always pay attention to it. If it's droping daily below the Low line you have a problem. If there's no problem with the cooling system the water line should stay put where you set it cold.

 

I'm not sure where it came from honestly. It's a 2012 and I bought it in 2014. I've never touched it myself.

https://photos.app.goo.gl/2uhfUidBL8Qcpa4DA

 

It seems it's correct then. Im at a total loss at this point.

 

Recap: if it overheated so many times it pushes coolant out into the reservoir and the reservoir makes a cloud of steam spraying crap everywhere.

Remember me writing saying the cap has three seals. Any one those fail to seat and all bets are off for your system refilling itself from the reservoir during cool down.

Please ditch that cap an buy an OEM cap.
Also, the roughness inside the fill neck could IMO prevent your cap from sealing. IIRC mine is a nice machined surface. Perfect for the caps inner secondary seal to mate too. Yours looks very corroded and could be a source for this problem.

Basically if the inner secondary seal fails when hot your coolant leaves the block and dumps into the reservoir. When the reser oir overflows coolant sparays everywhere as the fans are likely on during over heating events.

Make sense?

Edit - it might be the grain of the picture making it look worse than it is inside the fill neck. Still, get an OEM cap.

 

I ordered an OEM radiator cap yesterday and it is coming today. I also am ordering an OEM reservoir and cap with hoses. But all the shipping i've checked (lexuspartsnow, parts.lexus.com etc) won't get to me until 3-5 days. I might try dealerships and see if they have it so I can get it today.

I just drove around this morning with a reservoir tank filled just below the full line. Car started to overheat so I drove home with it around 240 degrees. Coolant was sprayed again below the reservoir tank on radiator hoses, water pump, oil filter cap etc. But the reservoir tank was still full.

Hopefully I can find that part today otherwise I'll have to wait till midweek next week.

 

Well the overflow tank will suck coolant back out the Radiator when it heats. So especially typically a overheat car shows a full and/or over full overflow tank. This really has me thinking there could be a slight possibility of a crack in the overflow tank. For years aftermarket Dorman tanks were the worst at this. Just a razor thin crack at the plastic seams, hard to tell until it expanded but enough to let air in system over and over. I may have missed some in all the pages but it does seems like a Bleed/Air problem.

Try this also, with nothing to lose. One day run the heat, and shut the car off. As soon as 1/2 hour maybe, you can twist the Radiator cap off (carefully!), leave the cap off overnight. The next morning top back off the coolant in that cap and put it back on. Most engines now air will make it's way out over night.

 

So I think I found my issue....Car was fine from Saturday till this morning. Car got up to 235 degrees before I shut it off and I could smell coolant. Opened the hood and coolant was sprayed all over. My upper radiator hose was detached and the piece that it connects to was missing a big chunk. I looked everywhere for the piece that broke off but couldn't find it so there is a good chance it has been missing for a while. The only major work I have had done to this car was my A/C compressor and a handful of other parts of the a/c system were replaced 2 yrs ago. I don't think they would have taken out my radiator to do all that work but who knows. The place I took it to has a good reputation and they "just hired a new Lexus expert" and he ****ed up my car so badly that the company had to pay Lexus to fix it all for me. $4,200.

Anyway... I can't seem to find the part # for a replacement frame for the cooling fans. I don't want to buy the whole assembly so do they even sell that piece separately? Is there anything I can do in the meantime as a bandaid? JB Weld? Idk..

 

Any progress on this OH issue?

 

Yeah after I made my last post about the cooling fan frame I realized that the broken piece was on the radiator and not part of the cooling fan frame. So I replaced the radiator.

So to recap, I have replaced the radiator cap, radiator, thermostat, upper and lower radiator hoses, coolant resevoir and engine coolant temp sensor. After installing the new radiator, i did a complete coolant flush. Getting to the engine block plug on the driver side was the biggest pain in my ***. My neighbors probably think im a psycho with the amount of curse words I was aggresively yelling at my car haha. Engine temp was 205-215 when fully warmed up. That lasted 8 days. Then yesterday on my way to get my son from school, I heard a squealing sound and I knew right away it was coolant spraying on the serpentine belt. Looked down at my gauges and saw the engine temp gauge climbing up. So the water pump is up next for replacement lol.

I can do it myself but I just said screw it and I am taking the water pump I bought and my car to Lexus dealership and having them install it. That way they can diagnose anything else that is going on.

 

I wonder if the seal failed from running water in it a few times as water has no lubricant for aged pump seal. Think of your knee to a gym floor.