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3.4 thermostat

Discussion in '1st Gen. Tacomas (1995-2004)' started by Hotdog7, Nov 2, 2023.

  1. Nov 2, 2023 at 4:23 PM
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    Hotdog7

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    Hotdog7 [OP] Well-Known Member

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    I guess this is going to be a poll. What position does the thermostat go the little pinhead at 12:00 or 6:00 I watch bunch videos I see both one guy said it's to let air leave so 12:00 makes sense
     
    Hotdog7, Nov 2, 2023
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  2. Nov 2, 2023 at 4:26 PM
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    0xDEADBEEF

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    0xDEADBEEF Trash Aficionado

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    On a 3.4 the jiggle valve goes down. On a 2RZ or 3RZ, it goes up.
     
    0xDEADBEEF, Nov 2, 2023
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    Area51Runner likes this.
  3. Nov 2, 2023 at 5:10 PM
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    Hotdog7

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    Hotdog7 [OP] Well-Known Member

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    What does it do? I have no idea just thought it made sense to go up
     
    Hotdog7, Nov 2, 2023
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  4. Nov 2, 2023 at 7:49 PM
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    Logans2001

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    Logans2001 What’s crackin’

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    3.4 v6 jiggle valve is at 6 o’clock. I believe it typically goes at 12 o’clock on most cars but everything I’ve ever read about the 3.4 v6 is that it goes at 6 o’clock. This must be the exception. Idk why. Others on here know more why about than me.
     
    Logans2001, Nov 2, 2023
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  5. Nov 2, 2023 at 9:47 PM
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    Digiratus

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    Actually, it will work at either position.

    However, when it is set to the 6 o'clock position, your coolant temps will run about 10°F lower than what is stamped on the T-stats housing.
     
    Digiratus, Nov 2, 2023
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  6. Nov 3, 2023 at 6:55 AM
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    Gen1andDone

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    Gen1andDone Well-Known Member

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    After my heads were replaced I noticed my operating temp was higher than it had been. It was in the mid or upper 190's. I decided to check the thermostat position and sure enough they had the jiggle valve at 12 o'clock. I repositioned it to 6 and operating temp returned to what I was used to, 186f.

    I use an OEM thermostat which I believe are 180f. So the 6 o'clock position is closer than 12.
     
    Last edited: Nov 3, 2023
    Gen1andDone, Nov 3, 2023
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  7. Nov 3, 2023 at 10:26 AM
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    Digiratus

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    FWIW, the OEM T-stat I had with the correct part number for my truck according to Toyota, had it's opening temp stamped (in C°) into its flange. IIRC it was 87.6° which converts to 190°F. When the jiggle valve was in the 12 o'clock position, the typical coolant running temps were 195-200°F. This is the same as when the truck was new.

    It is important to note that the higher running temps are ok and not too high when the rest of the system (radiator and fan and water pump) are all working within spec.
     
    Digiratus, Nov 3, 2023
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  8. Nov 3, 2023 at 1:09 PM
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    Gen1andDone

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    Gen1andDone Well-Known Member

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    That's odd, pretty sure the OEM t'stat for my '02 3.4l (
    $23 90916-03075 Thermostat
    90916-03075) is described as being 180f and has 82c stamped on it. I can't remember exactly when I started using the ScanGuage 2 to monitor temps, but I'm almost certain it was before the first t'stat replacement and it has always averaged 186f.
     
    Last edited: Nov 3, 2023
    Gen1andDone, Nov 3, 2023
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  9. Nov 3, 2023 at 1:26 PM
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    O'Silver_Taco

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    O'Silver_Taco Well-Known Member

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    Straight from toyota's horse's mouth....

    Jiggle....

    2.4 & 2.7 = Up (+ or - 15)
    3.4 = Down (+ or - 15)
     
    O'Silver_Taco, Nov 3, 2023
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    leid likes this.
  10. Nov 3, 2023 at 6:32 PM
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    Hotdog7

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    Hotdog7 [OP] Well-Known Member

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    I installed today 6:00 looks like this is how old one was in also.thanks for replays
     
    Hotdog7, Nov 3, 2023
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