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Discussion Starter #1
hi guys, recently bought an lexus 94 gs300 and the engine is same as NA supra so i might give it a try, after i drive the car for some distance, when i shut off the car, i can hear there is bubbling in my coolant reservoir tank. wat might cause that problem? even the coolant level will 'add up by its own 1 or 2 inches'. i dont see no white smoke or any funny leak anyway, no oil or coolant leak, no overheating on the temp gauge.
there is only one time , i have the upper radiator go 'flatten' after i drive it, i have to unscrew the radiator cap to release the pressure. i changed the radiator cap, now it didnt do it anymore beside only the bubbling sounds.
one of my friend told me about egr modulator, does it really relate to egr modulator?? or something else.
by the way, i flush the cooling system twice. wat else i can do to elimate the bubbling in the reservoir?
any suggestion?? thanks again.
 

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hi guys, recently bought an lexus 94 gs300 and the engine is same as NA supra so i might give it a try, after i drive the car for some distance, when i shut off the car, i can hear there is bubbling in my coolant reservoir tank. wat might cause that problem? even the coolant level will 'add up by its own 1 or 2 inches'. i dont see no white smoke or any funny leak anyway, no oil or coolant leak, no overheating on the temp gauge.
there is only one time , i have the upper radiator go 'flatten' after i drive it, i have to unscrew the radiator cap to release the pressure. i changed the radiator cap, now it didnt do it anymore beside only the bubbling sounds.
one of my friend told me about egr modulator, does it really relate to egr modulator?? or something else.
by the way, i flush the cooling system twice. wat else i can do to elimate the bubbling in the reservoir?
any suggestion?? thanks again.

I had this same issue with my supra and I had to burp my system because there was still air in the line somewhere. I would run the car with the heat blasting without out the rad cap on for a while and see if the the coolant level goes down at all.
 

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I had the same problem with my 95TT. I changed the rad cap and it was fine for a little while, but it did happen again...what else could it be?
 

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The Great Kruso
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I have the SAME exact car for one of my daily drivers and the SAME thing kept happening. The problem IS typically radiator cap related as stated above. Another major problem is if your car has an after market radiator... the cap does not sit flush within the top thus not sealing the system. Make sure the system is air tight when you install the new cap, you can try squeezing the upper radiator hose after installation to see if you get bubbles in the overflow tank.

Kruso
 

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make balloons with the hot air coming out of your radiator :)

My friend had the same problem a few years back, it was his radiator cap that was doing it.
 

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Discussion Starter #10 (Edited)
i know there is several kind of radiator caps, i bought 14lbs and 13lbs ....i still see 7lbs and 16lbs of radiator cap, maybe u guys are right, i know when i press down the radiator cap, the bubbling got worse....like keep bubbling more, when i unpress the cap, it bubble little by little..
ermmm...... i should try different cap then....currently i just have the 13lbs radiator cap,....maybe time for 16lbs cap??
 

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just to add my personal experience, i too had a worn-out radiator cap, but i also had an old hose (the one that exits the top of the engine near the firewall) obstructed, therefor probably creating air pockets and reducing cooling efficiency, took me a while to figure this out, since the stock temp gauge never even moved off center.

Also, i don't know if anyone already said this, but you could also adjust your coolant / water mix and add some redline waterwetter to your coolant system to improve its performance.

Luke.
 

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just to add my personal experience, i too had a worn-out radiator cap, but i also had an old hose (the one that exits the top of the engine near the firewall) obstructed, therefor probably creating air pockets and reducing cooling efficiency, took me a while to figure this out, since the stock temp gauge never even moved off center.

Also, i don't know if anyone already said this, but you could also adjust your coolant / water mix and add some redline waterwetter to your coolant system to improve its performance.

Luke.
HEy i know im 16 years late to the party but when you had that old hose go bad(mine is leaking under 10-15psi. Could this cause bubbles in the overflow tank in your particular experience?
 

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Old School
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HEy i know im 16 years late to the party but when you had that old hose go bad(mine is leaking under 10-15psi. Could this cause bubbles in the overflow tank in your particular experience?
Bubbles in the overflow tank are either headgasket or a leak on the suction side of the water pump. You won't get bubbling from a leak on the pressurized side of the pump.
 

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Bubbles in the overflow tank are either headgasket or a leak on the suction side of the water pump. You won't get bubbling from a leak on the pressurized side of the pump.
My leak is on the hose near cylinder 6 above the spark plug cover leading to the heater core. Sorry to ask is that the suction side? Leaking left side of the white line?
253014
 

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That's on the pressurized side so air isn't getting in there.
 
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