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Coolant leaving reservoir tank, why?

Discussion in '1st Gen. Tacomas (1995-2004)' started by vettehigh, Aug 7, 2022.

  1. Aug 7, 2022 at 2:29 PM
    #1
    vettehigh

    vettehigh [OP] Tacoma Tank

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    Over the past year or two I noticed the coolant level in the reservoir tank drop a few cups. I mark a redline and refill it with Toyota red/distilled water. The radiator coolant level is and always has been to the top when I remove the cap to check when cold. I replaced the radiator (OEM) a couple years ago along with all new OEM hoses, cap etc. On top of that: new OEM manifold gaskets, complete timing belt kit with all new OEM gaskets. The list of OEM new parts is endless. The fluid in the radiator is always to the top. There are no leaks. Pressure tested a few times. Oil is crystal clear and so is the exhaust. I even replaced the coolant tank and hose. For the life of me, I can't seem to find the reason why the res tank level drops over several weeks and I have to top it off again to the red line
     
    Last edited: Aug 8, 2022
  2. Aug 7, 2022 at 7:56 PM
    #2
    Bahamayellow

    Bahamayellow Well-Known Member

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    Probably just evap. I checked mine after last year and added a cup full. I dont think its getting into anything just been hot here in colorado.
     
  3. Aug 7, 2022 at 10:03 PM
    #3
    Old green toyota

    Old green toyota Well-Known Member

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    Oil leaks
    Not to scare you, but my truck started doing that. Then one day it drank almost all the coolant. It ended up being a headgasket. The prior owner gasket slapped it and pinched the fire ring.

    Just keep an eye on it
     
  4. Aug 8, 2022 at 7:17 AM
    #4
    O'Silver_Taco

    O'Silver_Taco Well-Known Member

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    Check your oil.......often.....
    and he's right ...... a leaking head gasket is kinda moody..... alright for a while.....managable...
    And then bam, I had the milkshake oil......


    Water can only get out three ways.....

    1) cap/hose, leak including radiator and heater core....a lot of potential leaks...
    Iac cooling hose, bypass tube gaskets, ect.....

    2) head gasket failing, usually leaks slow after you park it hot, steam press is at its max....and in later stage causes hard to restart when hot, wet plugs on affected cylinders......
    sometimes u can start it using other cylinders and burn off.....sometimes not....
    Go past a certain point and get to much water in any one cylinder.....and it hydro locks bending that rod.....destroys the engine...

    And lastly the worst.....a crack somewhere in head......usually a hairline crack between two valves....

    Good luck......my fix was reman block and new head........

    First thing I'd do is get a new radiator cap, maybe u got a bad on...
    And thermostat use oem with the Jiggle valve in proper angle for that engine...

    And they make UV dye just for this you know....the coolant one.....
    but that wont work if its the later two.... :(
     
    Last edited: Aug 8, 2022
    Nessal likes this.
  5. Aug 8, 2022 at 7:26 AM
    #5
    NAAC3TACO

    NAAC3TACO Middle aged member

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    Did you replace your radiator cap, too? That can be a source of evaporation. It was on my 1998 Corolla.
     
    vettehigh[OP] likes this.
  6. Aug 8, 2022 at 8:47 AM
    #6
    O'Silver_Taco

    O'Silver_Taco Well-Known Member

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    Out of curiousity, what coolant are u running, asian red, or classic prestone type??
     
  7. Aug 8, 2022 at 10:33 AM
    #7
    KdF

    KdF Old Rednek Type

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    Also, just for grins, check the heater relay on the firewall.
     
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  8. Aug 8, 2022 at 11:55 AM
    #8
    Bivouac

    Bivouac Well-Known Member

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    Remains to be seen I bought the tires and wheels the rest came along
    Your checking after the engine has set for a few hours and is cold?

    How much coolant in what time period ?

    Are you losing a quart a week or is it a quart every 3 months?

    Over the years I have found engines have a sweet spot the coolant level will adjust to that level .
     
  9. Aug 8, 2022 at 12:49 PM
    #9
    Sicyota04

    Sicyota04 Slowly but surely.

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    Looks like Toyota red/distilled water

    59418FB3-DFE0-4670-B47C-80F5F45349C9.jpg
     
  10. Aug 8, 2022 at 3:35 PM
    #10
    vettehigh

    vettehigh [OP] Tacoma Tank

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    My Royal Purple oil is clean as new and has been for years. I'm losing a few cups or so every few months, but only in the coolant jug. The coolant in the radiator itself is always to the max fill when I check and always has been. No smoke from exhaust whatsoever, nor any in the engine compartment. When I checked it yesterday, my truck was sitting for 2 days.
     
    Last edited: Aug 8, 2022
  11. Aug 8, 2022 at 3:36 PM
    #11
    vettehigh

    vettehigh [OP] Tacoma Tank

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    OEM red w/distilled
     
  12. Aug 8, 2022 at 3:37 PM
    #12
    vettehigh

    vettehigh [OP] Tacoma Tank

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    Yes
     
    NAAC3TACO[QUOTED] likes this.
  13. Aug 8, 2022 at 3:37 PM
    #13
    Taco302

    Taco302 Well-Known Member

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    It is a reservoir, for fluid if needed and a boil over also. Maybe it runs hot and dumps into the reservoir and drains out while you are driving. Are there any signs of residual coolant around the tank?
     
  14. Aug 8, 2022 at 3:43 PM
    #14
    Charvonia Design

    Charvonia Design Enthusiast-Owned Small Business Vendor

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    I just got a 2nd gen with only 54k miles and was noticing the same thing. I filled it to the Full mark, a week later it's a little lower. I also have white residue all around the radiator cap and hoses on the overflow tank. My plan is to wash it all off, replace the radiator cap, and keep a close eye on it for awhile.
     
  15. Aug 8, 2022 at 3:44 PM
    #15
    vettehigh

    vettehigh [OP] Tacoma Tank

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    No, I bought a brand new tank just in the case to old one was leaking that was replaced. Zero fluid on or around jug, same with radiator and hoses. Crystal clean
     
  16. Aug 8, 2022 at 5:25 PM
    #16
    Old green toyota

    Old green toyota Well-Known Member

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    Oil leaks
    Maybe set something up to capture the coolant coming out of the overflow, it will let you know if it's coming out of there or not. A water bottle ziptied to the hose will help troubleshoot.

    Coolant is going somewhere, in my experience when my gasket started to fail it was very unnoticeable until the truck overheated. Good luck, there's been plenty of helpful suggestions so far. You will figure it out!
     
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  17. Aug 8, 2022 at 5:48 PM
    #17
    vettehigh

    vettehigh [OP] Tacoma Tank

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    Ok. If it ever was the head gasket (highly unlikely on my end), how involved is the labor?
     
  18. Aug 8, 2022 at 5:53 PM
    #18
    Smokestacks

    Smokestacks Well-Known Member

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    what engine?
     
  19. Aug 8, 2022 at 5:54 PM
    #19
    vettehigh

    vettehigh [OP] Tacoma Tank

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    3.4 v6 5vz-fe
     
  20. Aug 8, 2022 at 6:03 PM
    #20
    O'Silver_Taco

    O'Silver_Taco Well-Known Member

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    Certain you've ruled out all external leaks......there's a lot going on a 5vz......
    I would do the dye test.....

    Talking to Kristi on another thread, got the same engine with water in tube #3, most likely a crack in the head somewhere......very bizarre leak.....
     
    Last edited: Aug 8, 2022

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