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Coolant spewing from reservoir

55K views 46 replies 6 participants last post by  Sptdog333 
#1 ·
Alright guys, I have a weird situation. So I have to fill my reservoir about pretty much every week because I'm losing coolant. I can see that the coolant is spewing from the top of the reservoir, hence the pressure is pushing it out that way. My best guess right now is that my overflow hose is clogged and the pressure from the radiator is causing the coolant to spew from the reservoir? Help please anyone or Jason. LOL Can someone explain how the radiator works also. Where does the coolant in the reservoir go to and how does coolant from the radiator come back to the reservoir (through overflow hose? if clogged then from bottom of reservoir? causing spillage?).
 
#38 ·
All the cap does is allow air and/or coolant to expel out of the breather hose verses it boiling over. There really isn't any pressure, more like just an overflow, but also acts like a vacuum when the car is cooling. As the coolant cools, it gets pulled back into the rad from the hose at the bottom of the reservoir, that's basically it.

If you go to Toyota, you would want to obviously call first to see of they have a reservoir cap in stock for an IS300. Toyota is cheaper but they usually do not have a lot of Lexus parts on hand so you may have to wait a day or two. You'd have better luck at Lexus and i can't see it being more than a few bucks(again, make sure they have one before going, at least i would).
 
#40 ·
I hear ya, this is strange. Well at least at the dealer you can simply return it but i have a feeling they'll have it. Just make sure to call the parts department to make sure they have em in stock. I'd tell em and show em the cap you have that won't fit. Good luck and hope it easily works out.
 
#41 ·
Giving an update on this, went to the local Lexus dealer in town and checked out their cap, it was the same one. That means my reservoir is probably not OEM however, after putting on the new rad cap the problem is currently solved. I haven't had to fill the reservoir at all this whole week or so. Good sign. Godspeed!
 
#42 ·
That is a good update and I'm stumped why the cap won't fit. Theoretically if the reservoir is filled half way when it's cold, it should not expel out of the reservoir, ever. I'd keep an eye on the reservoir level when the car is cold. It should always come back to the same spot.
 
#43 ·
I agree. Your reservoir is probably aftermarket if the oem cap doesn't fit. You should keep an eye on the marketplace for part-outs. You may be able to pick up a used OEM tank relatively cheap.
 
#44 ·
I just realized that the reservoir tank and fan shroud are one solid plastic piece. It is highly possible the Op's fan assembly was replaced with an OE aftermarket shroud at some point. That's the only other logical explanation that makes sense to me. Rvalero brings up a good point about checking for part outs as this shroud costs ~$160 at Sewell (before member discount).

It may be a Dorman shroud, again OE design and fit so you may not even be able to distinguish from a Toyota built shroud. See below.
2002 LEXUS IS300 Coolant Recovery Tank

Take a look here as well. If you want to get an OEM overflow, you have to get a new shroud. (#16711 below)

from Sewell... 16711-46350 FAN SHROUD




Ebay has a number of them too. Here's a few up for sale.

http://www.ebay.com/itm/01-05-Lexus-IS300-Radiator-Coolant-Overflow-Bottle-Tank-/130666195576

http://www.ebay.com/itm/01-05-Lexus-IS300-Radiator-Coolant-Overflow-Bottle-Tank-/110724439510
 
#47 ·
Thank you guys for the info in this thread. We took a road trip to AZ. Lost the ac condenser (won't engage) and at the south entrance to the grand canyon I notice temp want normal for the car. Pulled immediately over, had a gurgling noise, let the car cool a bit as we figured out (came here) what was going on. We had just replaced the radiator about 3 weeks prior (hit a big dog and put a hole in it). Checked the cap and it was shot. Pressure regulater piece in the center of the radiator cap came off causing the car to push coolant or the reservoir cap and run warmer then usual. We got enough water and babied it into Flagstaff to get a new cap. Again thanks!!!
 
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