Radiator not pulling coolant from overflow tank

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Thread: Radiator not pulling coolant from overflow tank

  1. #1
    2JZ NA-T
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    Radiator not pulling coolant from overflow tank

    Hey guys, im stumped. this is my 3rd thread today with questions i just cant seem to answer...

    my car has been running a little hot, especially after overheating at the track...but i dont think the track caused the problem, just excessive pulls back to back.

    anyways, 95 na-t, bl stg 2 kit, 2.5mm hg, factory NA radiator, with a ghetto overflow tank b/c i had to get rid of the factory one to fit the IC and the engine cover....

    im not sure what the problem is, i thought it was the thermostat, but i changed that today, as well as changing the rad. cap. brand new from toyota. car warms up just like needed, and stay cool, but after a while, start to build heat (this is after days and days of driving)... what im noticing is that the overflow tank fills more and more, and sometime when it runs hot enough even steams out of the top. but it never pulls it back in.... like today, after driving 20 miles, i let the car cool almost fully, opend my cap and saw no coolant in the rad, but the overflow tank was pretty much full, i fit half of the tank in the rad b/4 it filled up.... what in the world could be causing it?

    could the tank be crap? since we pretty much found it from a junked car? or maybe the way i have it set up? is the tank supposed to be oriented higher/lower then the rad? does it even matter? here is a pic, and thank you ahead of time.

    1995 6spd Borg Warner NA-t

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  3. #2
    SupraForums Member
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    Bhg

  4. #3
    SupraForums Member botchilah's Avatar
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    Quote Originally Posted by 1998jza80 View Post
    Bhg
    First thing that came into my mind but I didn't want to be a harbinger of bad news

    Still, if it IS BHG, it's not the end of the world
    1995 USDM Supra, AEM S2, assorted HKS goodies, AP BBK, custom widebodykit and FINALLY going single (with a bnew block)
    2009 Yaris 5-door TRD boy racer / DD

  5. #4
    iSketch Master! AlxRSPTT's Avatar
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    From what I understand you can put the cap on backwards on the overflow tank and it won't work right. Might have the hoses just hooked up wrong on it.

    http://www.supraforums.com/forum/sho...flow+backwards

    Alex
    Last edited by AlxRSPTT; 07-07-2009 at 08:40 PM.

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  6. #5
    2JZ NA-T
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    i have no other simptoms of a blown head gasket.... the tank isnt pressurizing, not bubling, just boiling with hot water. no wite smoke, compression still seems fine.... especially since i ran 4 passes after over heating, the last pass at the track was a 12.01.... so i doubt its the gasket... but how likely is it?

  7. #6
    iSketch Master! AlxRSPTT's Avatar
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    I just showed you the easiest thing to check that resembles your symptoms. Go do it!

  8. #7
    SF.com Member #0000000023
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    re: overflow tank, if you open the cap, is there a tube that extends to the bottom of the tank? Any breaks/cracks in the tube? Fits to the cap snugly?

  9. #8
    RoastBeefCurtain Commando PM-Performance's Avatar
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    Im surprised no one has informed you yet on how an overflow tank works.
    This is a one way setup that when the spring pressure is met in the cap, that the seal in the cap pushes open and relieves pressure and fluid into the over flow tank
    Therefor, it will not flow back, nor do you want it to.

    If it runs fine sometimes and overheats sometimes, i would maybe try burping the coolant system. maybe there are air bubbles. Also maybe try a heaver spring pressure in the cap.
    You would likely see more symptoms if it was a headgasket issue.
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    2JZ NA-T
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    hm.... i never even thought about it being a one way system, for some reason i assumed that once the coolant heats and expends, it overflows into the tank, and when it contracts, it gets pulled back. but now that i think about it, there wouldnt be a way for it to flow back ...... you sire are correct, i just rented some tools from autozone (compression tester, and also some sort of a rad. comp. testes to see if it pressurizes too much) so i'll run some tests and then try burping the system.

    how easy is it to get air bubles into the system?

  11. #10
    2JZ NA-T
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    i take that back, you are wrong. olde cooling system were set up like that , it was called an "open" system, but the problem with it was that since the system is pressurized, once the coolant expands it leaks into the overflow tank, leaving lesser and lesser amounts of coolant to do the cooling, cauzing the engine to run more and more hotter, this problem was solved by combining both the open and closed system which adds an adition seal on the rad cap. once the engine starts to cool, it creates a vacuum b/c of all the fluid that exited to the overflow tank, this vacuum and the upper sealing seat of the cap allow coolant to be pulled back into the radiator from the overflow tank.

    just wanted to clear that up.


    but it is possible, and most likely, that i do have an air buble in the system.... or maybe the cap on the tank is just bad...

  12. #11
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    Also, before you blurp the coolant jack the front of the car up to make the radiator the highest point of the coolant system.

  13. #12
    SF.com Member #0000000023
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    Yes, this is exactly how it works, coolant flows both ways. The overflow also helps to keep air out of the system. Any small air bubbles enter the overflow tank and float to the top, when it cools, only liquid is drawn back in.

    Quote Originally Posted by Ravan17 View Post
    i take that back, you are wrong. olde cooling system were set up like that , it was called an "open" system, but the problem with it was that since the system is pressurized, once the coolant expands it leaks into the overflow tank, leaving lesser and lesser amounts of coolant to do the cooling, cauzing the engine to run more and more hotter, this problem was solved by combining both the open and closed system which adds an adition seal on the rad cap. once the engine starts to cool, it creates a vacuum b/c of all the fluid that exited to the overflow tank, this vacuum and the upper sealing seat of the cap allow coolant to be pulled back into the radiator from the overflow tank.

    just wanted to clear that up.


    but it is possible, and most likely, that i do have an air buble in the system.... or maybe the cap on the tank is just bad...

  14. #13
    2JZ NA-T
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    i just burbed the system, i saw 3 or 4 bubles come up out of the rad. and spill a bit of coolant out and then drop significantly...so i gues it was full of air?? i hope that solves the problem. the thing is that my cap has been opened so many times that it is possible that i got some air trapped in there really easy. im going to jack up the car and burp it once more just to make sure all of it is out like suggested.


    i appreciate all of the help guys. i hope this solves the issues ive been having.


    thanks again.

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    RoastBeefCurtain Commando PM-Performance's Avatar
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    ahhh I learned something new today. I never knew it created a suction to pull it back in.
    Interesting.

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    Quote Originally Posted by Ravan17 View Post
    i just burbed the system, i saw 3 or 4 bubles come up out of the rad. and spill a bit of coolant out and then drop significantly...so i gues it was full of air?? i hope that solves the problem. the thing is that my cap has been opened so many times that it is possible that i got some air trapped in there really easy. im going to jack up the car and burp it once more just to make sure all of it is out like suggested.


    i appreciate all of the help guys. i hope this solves the issues ive been having.


    thanks again.
    Your rad cap being open wont cause air to be trapped.the air your seeing is from the air that was trapped in the motor, hoses ect when replacing the coolant.
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    2JZ NA-T
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    yea ure right, i was just thinkin about that myself, lol.

    but i think i know how this problem started. i had a faulty radiator cap which busted and allowed all of the hot coolant to overflow into the tank, evetually i was running so low that i overheated a bit at the track. and i gues between filling in the coolant, changing the thermostat, and all that stuff i got some air bubbles....

    im just glad it wasnt my gasket, even though i was sure it wasnt since i had absolutly no symptoms of it.


    i am going to burp the system one more time with the front end jacked up right now to see if there is any air left in there.


    and PM, we learn something new everyday hell, atleast i do

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    RoastBeefCurtain Commando PM-Performance's Avatar
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    yea anytime I mess with coolant stuff I try to burp it to make sure no air got in.
    I can see that happening from what you mentioned above though.
    That should fix it IMO.

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    SupraForums Member slither's Avatar
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    First thing I would check would be to make sure the siphon tube(SP??) in the overflow tank is not bad(or make sure its even there). Then check for air in the system. I recommend this since the first is the easiest to do, and neither will cost you any money. If its still doing the same thing, post back in here. Goodluck

  20. #19
    2JZ NA-T
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    well only thing is that i dont ahve the factory tank, this one only has one tube that goes in, not two like the supra, so i couldnt have reversed the lines, it wents the air through a special vavle in the cap.


    now i burped the systemwith the car jacked up, but now im doing it with the heater on also, b/c i got another pretty big air buble out as soon as the heater turned on.


    when i test drove it everything was fine for a couple of pulls , but when i started coming to a stop the heat began to rise again. but then i realized i didnt top off the fluid in the radiator when i burped it, it lost quite some fluid from the 3 times. and i also forgot to put the heater on, im doing that now.


    good news is that after the water expanded into the ove flow tank, it started sucking right back in as the engien was cooling, thats already a major progression with my problem. i hhope this last time fixes it period.


    thanks

  21. #20
    SupraForums Member botchilah's Avatar
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    yeah I hope you fix it good now.

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    Also check that the fan is working correctly,

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    2JZ NA-T
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    i think i figured it out guys....... i dont think that it was my coolant system that was at fault.... i just noticed ...well just now started really payin attention to my AFRs and boost levels... i was only tuned to run at 16 psi, and even at that my injector duty cycle was at 85%... so imagine what its doing at 17 and 18 psi.... or even worse, when i hit 20psi on the way back home today. my afr was 13.3, i belive thats whats causing my coolant to start boiling into and out of my overflow tank, and then went its time to pull it back in, since it boiled out as hot vapor, there is a shortage, so after a couple of cycles like this, i start to be low on coolant...

    so now im off tryin to figure out how to get a bit more fuel w/out retuning my car...

  24. #23
    SupraForums Member slither's Avatar
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    You could TRY bumping fuel pressure, it might work or might not. However, Id retune it. You got AEM or?

  25. #24
    2JZ NA-T
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    i got AEM

  26. #25
    SupraForums Member slither's Avatar
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    check your pm's

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