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2003 IS300
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Discussion Starter #1
My coolant reservoir was damaged from last crashed. I didn’t bother to change it because my radiator is still good. A week ago. My Is300 overheated. I noticed my radiator cap is broken. Maybe it was the reason it overheated? I replaced the radiator cap and thermostat. Everything is good now. Not over heating anymore but I can smell coolant after driving my car. Is this because my reservoir is cracked?

FYI. before my IS300 overheated I can hear a water rumbling while driving for days. Not sure if this sound is a sign of low coolant or maybe the thermostat is not working properly.
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2003 IS300
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Discussion Starter #3
Are you sure the radiator isn’t cracked or leaking? Yes the water movement you here would be low water and air pockets moving around through the heater core.
Yes I am sure. No leak. I park my car in my driveway. No leak. But I have a feeling it’s probably going out through coolant reservoir (cracked) while driving. That’s why I’m smelling coolant after driving it. Do you think this is possible? Does coolant goes in reservoir while driving?
 

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Does coolant goes in reservoir while driving
Yeah, for sure. Heat in the rad increases pressure, and so the coolant has to go somewhere. Instead of spilling it goes into the overflow. When the rad cools back down, pressure decreases and pulls the coolant back from the overflow and into the rad.
I’d test if the overflow leaks by parking the car and when it’s cool, add some water to the overflow and see if you can find a leak. If the water level drops while sitting you have a leak. You want to make sure and get all the tap water out of the overflow after your test because tap is not good for the rad, and will raise your freezing point if some of it gets drawn into the rad. You could also “bootstrap” a test overflow out of a pop bottle that’s secured under the hood and put the overflow hoses into it, drive it, and see if the smell persists. If you’re positive you’re not losing coolant from a leak or a bug then you probably are just smelling residual coolant that’s getting baked as you drive.

water movement you here would be low water and air pockets moving around through the heater core.
Yes mine does that. It’s hard to get all the air out and I am pretty sure there’s not a “high point” bleeder screw to purge the air.
 

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Every so often with summer and windows down i get a waft of smell of coolant from mine, it is just some drips of coolant that has settled somewhere after changing the water pump and timing belt last year.

My buddy had a cracked head in his Santa fe a couple of years ago, blew coolant all over the engine bay. He got it repaired and works fine now, but when we are towing his boat and the engines warm i can still smell the dried coolant in the nooks and crannies of the engine pretty strong.
 

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Mr. Roo
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Yeah, for sure. Heat in the rad increases pressure, and so the coolant has to go somewhere. Instead of spilling it goes into the overflow. When the rad cools back down, pressure decreases and pulls the coolant back from the overflow and into the rad.
This. You need an intact overflow bottle for the extra coolant to go into when hot. Right now, your coolant is just overflowing and being evaporated by the hot engine components so you can smell it. It's a little bit over time, slowly. But now your radiator can't pull any fluid back. After enough of these cycles, it will run out of coolant and overheat more and more.
 

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2005 Lexus IS300
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This. You need an intact overflow bottle for the extra coolant to go into when hot. Right now, your coolant is just overflowing and being evaporated by the hot engine components so you can smell it. It's a little bit over time, slowly. But now your radiator can't pull any fluid back. After enough of these cycles, it will run out of coolant and overheat more and more.
This, I changed out two radiators in the past thinking they were leaking when it was really my overflow was cracked and slowly leaking over time.
 

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Mr. Roo
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Thanks everyone. I replaced my coolant overflow. It wasn’t easy to replace that 😅. It’s very tight to pull it out. I had to pull up the radiator half way to got it out.
Nice! I find it easier to just drain and remove the whole assembly, do the work, and then put it back. I've done it so many times by now, it's easy and fast. I hope it fixed it for you!
 
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