Apparently I have a leaky radiator which mostly emptied out. I had the car parked and idling when I got out to show a friend how awesome my brand new car is... We were hanging outside for a good 5-10 minutes. I got inside and holy crap the temperature needle as near the RED H.

I immediately shut the car off and opened the hood.

No warning lights came on the dash and the engine oil still looks brand new (mobil 1 synthetic)

The car cooled off right away and didn't overheat again. Everything seems ok so I'm not too worried about it

So my question is what happens on these cars when they over heat..

Does the car beep and flash warning lights at you or does it just let you burn it up in flames ?

 

I can't say and don't want to find out, but I would think there would be a warning light on top of the needle? After that I would think it's like any other car, the heads warp and coolant leaks?

Don't you want to investigate why this happened? Is there coolant in the reservoir? When I bought my car used, there actually was not. I was pretty alarmed, but then learned here that it's often neglected since it comes with Super Long Life Coolant from the factory, and the cap is under the air intake plastic thingy and viewed from the back side, and it evaporates over time...

p.s. if you need coolant Walmart sells Asian (pink) sllc2, and it is below $9/gal for 50/50, but you order it online and pickup in the store for that price, otherwise it's about $12 on the shelf...Toyota gets over $25/gal. for the pink stuff....the red is 100% and I think the same price...

 

I know why it happened.. The car was in a front end accident causing a small leak in the radiator.. A used original lexus radiator is on the way (the last 2 were unusable junk on good ol ebay) but I figured car was not over heating I could show the newly fixed car off a bit sure enough it picked the worst time for that to happen..

Funny you mention the plastic thingy near the cap connecting to a hose.. on the newest radiator it is broken off.. I'm thinking I can still fix it/make it work.

I'll look today to see where that warning light is.
taking on the assumption here, no warning lights = no problem.. this time atleast

 

Better it happened while the car was sitting rather than out on the freeway.

 

Although the temp may have remained lower on the highway due to the airflow, meaning the fans should go crazy either way, but on the highway there is the added benefit of airflow from the highway speed...

at the same time my coolant was low when I bought my car, meaning even the radiator was not full....yet the temp never went above normal....that's why I didn't discover it until day 2...

 

Agree but at some point it's a problem. The idea of a radiator leak on a busy freeway miles from home doesn't appeal. Also I don't want to see someone's LS with the hood open and steam everywhere. Hard for them and also spoils the car's reputation

 

Running a car with a cooling problem is an invitation to disaster. Why risk it?

 

Overheating can and will cause blown head gaskets on these cars. My experience with other Toyotas is that as soon as the temp gauge moves out of the normal range it is already too late.

 

You can only imagine what went through my mind, about 36 hours after my purchase, poking around a 21:00 EST on a Sunday, and finding zero coolant in the reservoir. I've never seen that before on any car. But as mentioned, the temp was normal at all times. About 13k later, and through a timing belt/water pump job, I know the car doesn't lose a drop of coolant (I guess it might take 10 yrs. to evaporate in those amounts)....used to be fluid loss could be ignored, even oil (maybe not brake or clutch fluid). Nowadays, with things being so tight, some motors an oil leak can cause a serpentine belt to walk, and the belt can get sucked into the motor through the front seal....

 

I love good old fashioned temperature gauges like the ones that they use on the 430 but they are virtually useless if you don't look at them. And the fact of the matter is that most people don't pay any attention to them (myself included) unless something goes wrong to draw your attention to the dash. Judging by this thread and a few others on this forum it looks like Lexus did not back that up with an audible alert and/or message on the display panel. To me this is a huge shortcoming for a car of this stature.The ECM monitors coolant temperature. It seems like it would have been a trivial thing for Lexus to add that feature to the car...

 

So there is NO WARNING LIGHT or alarm ? I may have read in an owners manual that there was a red temperature alert. I think I'm actually going to check that right now while I have a moment.

 

Holy crap there really is NO warning light or alarm according to owners manual. I am still just a little worried but car drives normal oil looks good so should still be ok.

 

It is too late once the oil has coolant mixed in with it. My oil is still looking brand new. I've heard of needles going way past the red H on other cars and still being ok. Who knows.

 

I did a stonking great big burnout in my LS430 (Australian-style burnout, not a weak American line lock standstill burnout), the temp was well into the red and it dumped a whole lot of water out onto the burnout pad. When i saw it was in the danger zone I hopped off the pad and sat it there idling for a few minutes for the temp to come back down. Other than losing 2 litres of coolant and some engine oil from the workout at 5000 RPM, nothing untoward has happened to the engine. No blown gaskets, no warped heads, no lost compression, no transmission damage...Toyota builds their engines stronger than a brick s**thouse. My daily has a crack in the top tank on its radiator and as long as I keep an eye on the coolant level, I can sit the thing in traffic and it doesn't even move off halfway, and its a 3S-FE automatic, which have a habit of getting hot when you don't want them to. I have a Caldina radiator going into that one but requires some mounting and hose modifications to make work. Nothing too major.

 

That's the only explanation I can think of as to why there is no Engine burnout warning light - The engines don't burn out.