LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

overheating issues

Old 07-26-16, 05:59 PM
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daveskates
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Default overheating issues

So the car got pretty hot the other day, i think there's an issue with the fans, I'm curious how sensitive are the headgaskets to overheating in the 1uz? i know some cars are first time it hits red (on the temp gauge) and it's a wrap. While some cars have gone until the car shut down because it was so hot. The car got hot on me but i did shut it off as soon as i saw it when it hit the needle. There was never any smoke coming from under the hood or anything like that, and there definitely was enough coolant but i think the fans weren't working. I don't necessarily need help diagnosing the issue to fix it, im just wondering how hot have some of you guys have the car run and if there was any damage or if i should be ok and not over think it.
Old 07-26-16, 07:58 PM
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jaaa
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Originally Posted by daveskates
So the car got pretty hot the other day, i think there's an issue with the fans, I'm curious how sensitive are the headgaskets to overheating in the 1uz? i know some cars are first time it hits red (on the temp gauge) and it's a wrap. While some cars have gone until the car shut down because it was so hot. The car got hot on me but i did shut it off as soon as i saw it when it hit the needle. There was never any smoke coming from under the hood or anything like that, and there definitely was enough coolant but i think the fans weren't working. I don't necessarily need help diagnosing the issue to fix it, im just wondering how hot have some of you guys have the car run and if there was any damage or if i should be ok and not over think it.
I had mine get towards the upper range when I first got it and had several leaks. Once I resolved the leak problems haven't had any problems with the engine at all. If that had been my Beemer, another story.
Old 07-26-16, 08:45 PM
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the upper level like it hit the red?
Old 07-26-16, 09:52 PM
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CELSI0R
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Originally Posted by jaaa
I had mine get towards the upper range when I first got it and had several leaks. Once I resolved the leak problems haven't had any problems with the engine at all. If that had been my Beemer, another story.
Out of curiosity, what kinds of leaks did you have and from where on the engine?
Old 07-27-16, 03:03 AM
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Its not so much a head gasket deal as it is a warpage deal, distortion from the heat.
Old 07-27-16, 03:30 AM
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Head warpage almost always occurs FOLLOWING a prolonged blown head gasket, it will next to never occur without a BHG.

OP- it's russian roulette, if the radiator cap didn't blow then hopefully you didn't overheat it at all. Resolve the cooling issue that caused the issue (water pump, leak, low coolant, or air bubble are my top picks, not in order) and you should be fine.
Old 07-27-16, 06:45 AM
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Originally Posted by CELSI0R
Out of curiosity, what kinds of leaks did you have and from where on the engine?
Got right at the red zone first time it happened. In order: Front crossover bridge, cracked thermostat housing, leaking water pipe on the back side of the water pump(from when I replaced my starter- this took two extra intake removals to fix), leaking petcock gasket, leaking radiator outlet pipe to overflow tank(tried to bj weld), replacement radiator had leak at temp sensor housing, and lastly a leaking water pump gasket that got replaced when I threw the gates timing belt kit on it. At least two of my leaks were self induced as I was working on other parts of the car(clumsy/inept).

Last edited by jaaa; 07-27-16 at 06:54 AM.
Old 07-27-16, 08:26 AM
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Wow, ok. Thank you for the info, jaaa! Sorry you had to go through all of that.
Old 07-27-16, 08:31 AM
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Originally Posted by CELSI0R
Wow, ok. Thank you for the info, jaaa! Sorry you had to go through all of that.
All I can say is it's been a learning experience. I've had the car for just over a year, and the last three weeks is the longest I've gone without a coolant leak of some kind. I knew I was in trouble with my $300 car when I pulled three partial jacks and a partial jug of coolant out of the trunk when I bought it.
Old 07-27-16, 03:40 PM
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Originally Posted by PureDrifter
Head warpage almost always occurs FOLLOWING a prolonged blown head gasket, it will next to never occur without a BHG.

OP- it's russian roulette, if the radiator cap didn't blow then hopefully you didn't overheat it at all. Resolve the cooling issue that caused the issue (water pump, leak, low coolant, or air bubble are my top picks, not in order) and you should be fine.
And why does the head gasket blow? It is clamped securely between the deck surface and the head surface. The fasteners are preloaded to maintain pressure on that union.
The stress is doing something to cause a head gasket to fail, and when it fails its not the whole gasket that fails, only a certain area that has lost the clamp force. Gaskets just don't fail for the fun of it.
Old 07-27-16, 06:05 PM
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Originally Posted by PureDrifter
Head warpage almost always occurs FOLLOWING a prolonged blown head gasket, it will next to never occur without a BHG.

OP- it's russian roulette, if the radiator cap didn't blow then hopefully you didn't overheat it at all. Resolve the cooling issue that caused the issue (water pump, leak, low coolant, or air bubble are my top picks, not in order) and you should be fine.
roger that, and you mean the cap blow as in it coming off of the radiator due to pressure? basically i did see some steam coming from under the cap. let it sit and cool down, parked the car for half the day, went back turned it on and it didn't smoke or anything from the exhaust which is a good sign. I also have seen people drive a car hot until it literally shuts itself off and that didn't happen either. Maybe i'm being paranoid or over caution which isn't necessarily a bad thing. Think I should be ok for the most part then?

also when the needle hits red, about how much is the temps in farenheit at red?
Old 07-28-16, 03:01 AM
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Originally Posted by dicer
And why does the head gasket blow? It is clamped securely between the deck surface and the head surface. The fasteners are preloaded to maintain pressure on that union.
The stress is doing something to cause a head gasket to fail, and when it fails its not the whole gasket that fails, only a certain area that has lost the clamp force. Gaskets just don't fail for the fun of it.
That's not how that works. What you're saying as best I can understand is that all blown head gaskets are caused by head warpage. This is completely incorrect. Head gaskets can blow without causing the head to warp, depending on the materials used in the block and head and how badly the vehicle was overheated. Warping the heads on most vehicles is VERY rare, even when BHGs are common. (Somewhat more common on vehicles with iron blocks and aluminum heads, such as my old mk3 supra).

https://en.wikipedia.org/wiki/Head_gasket
I urge you to educate yourself, there are myriad factors that cause blown head gaskets, most commonly being improper torque on the head/block union (see: 7M BHG issues), overheating, and detonation int he cylinders.
Old 07-28-16, 05:40 AM
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Originally Posted by PureDrifter
That's not how that works. What you're saying as best I can understand is that all blown head gaskets are caused by head warpage. This is completely incorrect. Head gaskets can blow without causing the head to warp, depending on the materials used in the block and head and how badly the vehicle was overheated. Warping the heads on most vehicles is VERY rare, even when BHGs are common. (Somewhat more common on vehicles with iron blocks and aluminum heads, such as my old mk3 supra).

https://en.wikipedia.org/wiki/Head_gasket
I urge you to educate yourself, there are myriad factors that cause blown head gaskets, most commonly being improper torque on the head/block union (see: 7M BHG issues), overheating, and detonation int he cylinders.
I was once out on a test range(not far from death valley) in my Datsun B210. I sprang a leak in my radiator, but couldn't stop due to certain material in the car at the time. I drove 35 miles in 110 degree weather with not a drop of coolant in the car. It pinged and sizzled for over an hour after I parked it. I was amazed that it only took me putting on a new head gasket to fix it.
Old 07-28-16, 09:48 AM
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Originally Posted by PureDrifter
That's not how that works. What you're saying as best I can understand is that all blown head gaskets are caused by head warpage. This is completely incorrect. Head gaskets can blow without causing the head to warp, depending on the materials used in the block and head and how badly the vehicle was overheated. Warping the heads on most vehicles is VERY rare, even when BHGs are common. (Somewhat more common on vehicles with iron blocks and aluminum heads, such as my old mk3 supra).

https://en.wikipedia.org/wiki/Head_gasket
I urge you to educate yourself, there are myriad factors that cause blown head gaskets, most commonly being improper torque on the head/block union (see: 7M BHG issues), overheating, and detonation int he cylinders.
I had a story written and deleted it all.


The topic was over heating not chemical attacks, improper assembly, etc.

Last edited by dicer; 07-28-16 at 01:07 PM.
Old 07-28-16, 09:46 PM
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Originally Posted by jaaa
I was once out on a test range(not far from death valley) in my Datsun B210. I sprang a leak in my radiator, but couldn't stop due to certain material in the car at the time. I drove 35 miles in 110 degree weather with not a drop of coolant in the car. It pinged and sizzled for over an hour after I parked it. I was amazed that it only took me putting on a new head gasket to fix it.
that sucks man, im assuming you started it up again. Did it smoke? oil mixed with the coolant? etc.

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