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Auto Trans temp question

Discussion in 'Technical Chat' started by cr500taco, Mar 4, 2015.

  1. Mar 4, 2015 at 5:40 PM
    #1
    cr500taco

    cr500taco [OP] Well-Known Member

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    I have a 97 4wd 3.4L with auto. The trans was rebuilt just over three years, ago. Last year, about a month out of warranty (had a two year warranty), it started slipping on me and on my way to the trans shop it for it, it completely stopped working, so I had it towed the rest of the way. They checked the fluid and said it was burnt and that the trans overheated and pulled the trans apart to see why, but didn't find anything. They did replace the converter under the warranty, because they said it was bad, but didn't know if that caused the trans to overheat or if the overheating ruined it. Recently, I installed a trans gauge, to keep an eye on the temp. My trans shop brazed the sender on the pan and said that was the best place to read the temp. So, I've been keeping an eye on the temps, but not sure where the norm should be at and how much is should heat up and cool down under normal driving conditions. I have read that anything over 200* for long periods of time is bad for the trans. The last couple of weeks I have been driving about 45 miles one way for work. In the mornings leaving my place at 5am with the ambient temp about 40* - 45* the trans temp reaches about 165* max going through moderate hills and usually runs about 160* through flat areas. Once, I get off the freeway, it shoots up to about 180*, maybe slightly more. Coming home from work, leaving just after 2:30, with the ambient temp about 70* or so, on the flats it runs about 165ish*, but once I hit the hills, it shoots up and has reached about 220* and then cooling down slightly to about 210 driving on city streets. I stopped by my trans shop, yesterday to schedule a service for this Saturday. He asked me how the trans temp was and I told him that it's reached 220. He asked me how the coolant temp is, which runs at 190*. He said the trans is running hot and that temp should be around where the coolant temp is (which makes sense) and said hopefully, he'll see why it's running hot when he does the service.

    Just wondering if anyone, could shed some light on what's possibly going on?
     
  2. Mar 6, 2015 at 4:38 AM
    #2
    cr500taco

    cr500taco [OP] Well-Known Member

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  3. Mar 6, 2015 at 5:07 AM
    #3
    gearcruncher

    gearcruncher Well-Known Member

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    Copied from the transmission page
    .
    .
    .
    TRANSMISSION COOLERS
    If you do not have a transmission cooler on your truck and you plan to tow or haul heavy loads or you are in heavy stop and go traffic and use 4X4 low a lot , consider purchasing a cooler . The cooler thats built into your rad is designed to cool the transmission with the weight of just the truck by itself .When you are in 4x4 low , your torque converter is usually in the stall stage and creates a tonne of additional heat .
    160 - 200 are considered normal temps providing your engine radiator is functioning properly . If your engine overheats , your transmission will also overheat
    Normal fluid temperature in transmission to be 175 deg. F.

    Rate of oxidation to double for each temperature increase of 20 deg F above normal (175 deg F). As oxidation rate doubles, useful life of fluid is cut in half.

    At 175 deg F life is 100,000 miles
    At 195 deg F (20 deg above 175) life is 50k miles
    At 215 life is 25k miles
    At 235 life is 12k
    At 255 life is 6,250
    At 275 life is 3,000
    At 295 life is 1500
    At 315 life is 750

    At temperatures much above 300 deg F the metals in the transmission will tend to warp, twist etc. high temperatures causes the formation of varnish deposits which impair or pre vent transmission operation.

    At a fluid temperature of 415 deg F fluid life is 30 minutes!

    Source: Empire Lubricants Inc.
    Consider a scan guage [​IMG][​IMG][​IMG]http://www.amazon.com/ScanGauge-Comp.../dp/B000AAMY86
    Here is the best information for the scan guage http://www.tacomaworld.com/forum/2nd...-pressure.html

    You could also use the Torque app with an Android phone as a cheap alternative to watch your temps http://www.tacomaworld.com/forum/per...d2-reader.html

    This is how Low Pressure Drop technology works::
    When Automatic Transmission Fluid (ATF) is cold it is viscous. The unique Tru-Cool design allows the colder, thicker ATF to flow more efficiently through two open bypass channels positioned at the top of the cooler. As operating temperatures increase, the ATF becomes hotter and thinner, It's then directed through the core where it is cooled. Tru-Cool's highly efficient cooling technology combines improved protection against lube failure with optimal heat transfer.
    [​IMG][​IMG][​IMG]http://www.amazon.com/Long-Tru-Cool-.../dp/B005XZXB1M
    Long Tru-Cool Oil Coolers offer advanced cooling protection for many towing applications. The advanced technology out performs TUBE & FIN Designs, Delivers up to 15 times less flow restrictions, 30% more cooling delivers maximum heat transfer, Self-Regulating for maximum lube flow protection through start-up, varied temperatures and driving conditions, heavy loads and towing.
    Here is Toyotas fluid flow guide ...Look at page 8 on this PDF http://www.toyotatundraforum.com/pdf/A750E.pdf
    And here is a guy who recently installed a cooler correctly http://www.tacomaworld.com/forum/1st...agram-pic.html

    cooler and fan install http://www.tacomaworld.com/forum/2nd...n-install.html
     
  4. Mar 6, 2015 at 5:33 AM
    #4
    gearcruncher

    gearcruncher Well-Known Member

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    I should add to this .

    Are you sure your transmission is functioning properly ?
    http://www.tacomaworld.com/forum/te...warner-340-series-transmissions-write-up.html

    Transmissions can overheat due to wear or leaking circuits inside the valve body . Even if your cooling system is functioning fine , there may be a reason you are hitting high transmission temps .

    When the transmission shop rebuilt your transmission , did they recalibrate the valve body to compensate for torque converter slippage and overheating ? Check your original invoice for the recalibration kit .
    http://www.transgo.com/products.php...d=253&countdisplay=1&start=0&addcountview=Yes
    .
     
  5. Mar 6, 2015 at 1:45 PM
    #5
    cr500taco

    cr500taco [OP] Well-Known Member

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    Thanks for the reply. I don't think there is anything wrong with the tranny. It shifts fine and doesn't slip. The radiator is new, installed it little over a month ago and the coolant temp is always between 188 - 193. I do have a cooler installed, but need to hook it back up. I will check to see if the shop calibrated the valve body.
     
    Last edited: Mar 6, 2015
  6. Mar 6, 2015 at 6:06 PM
    #6
    cr500taco

    cr500taco [OP] Well-Known Member

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    Another thing that I meant to ask, I am understanding that the temp shouldn't fluctuate much if at all, if accelerating/decelerating and going up and downhill? The temp does climb about 15* going uphill and goes down a little going downhill.
     
  7. Mar 7, 2015 at 5:15 AM
    #7
    gearcruncher

    gearcruncher Well-Known Member

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    15 degrees is fairly normal for climbing hills . When your torque converter lock up clutch unlocks you will see a rise in temperature , usually climbing hills or passing a vehicle will raise the temps up quickly . I think your biggest issue is the transmission going well over the 200 mark . Try connecting the cooler back up and see how that helps . Connecting the transmission cooler should keep the temps below 200 and prevent your transmission fluid from breaking down so quickly .
     
  8. Mar 9, 2015 at 7:24 PM
    #8
    cr500taco

    cr500taco [OP] Well-Known Member

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    Had my trans serviced at the Trans shop on Saturday. The mechanic who worked on it said that the fluid looked and smelled fine and didn't show any signs of it getting hot. Stopped off at the shop today because the gauge showed up to 230* on my way home from work. The owner looked at the fluid and also checked the trans pan and sender temps with the temp gun with the truck running, after being off about 5 mins. He said that the fluid was cool to the touch and the pan temp was 175* and the sender temp was 154* with the gauge reading about 195*. He thinks that either the sender or the gauge is bad, most likely the sender and recommended putting a b&m sender in, which I have an auto meter sender and temp gauge in right now. Will the b&m b compatible with tbe auto meter?
     
  9. Mar 10, 2015 at 5:22 AM
    #9
    gearcruncher

    gearcruncher Well-Known Member

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    Thats a question that can only be answered by comparing the specifications of the two different sending units .
    Your truck is a 97 which means it is OBD2 compliant . I am wondering if a scan guage or Ultra guage would also work in place of the Auto meter guage . A scan guage or ultra guage would give you the benefit of multiple guages from one source . You should research those before going with another independant analog guage . They are both similar in price and offer a lot more information .
     
  10. Mar 10, 2015 at 5:47 AM
    #10
    cr500taco

    cr500taco [OP] Well-Known Member

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    Yeah, I am going to get another sending unit to see. Fortunately, they are cheap. Just not sure if I want to get the sam e one or if a different brand will work.
    I do have a scan gauge, but my OBDII doesn't have trans temp. Toyota didn't start adding that on the Tacoma's until later years. Not sure when, but I want to say '99 or 2000.
     
  11. Mar 11, 2015 at 6:18 AM
    #11
    gearcruncher

    gearcruncher Well-Known Member

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    Trans temp has been around for a long time . Its not that you dont have a transmission temp sensor inside your transmission ...You do ,the communication with the trans temp sensor is the issue . . Gonna have a look to see what I can find for you .I will get back to this in a day or two .
     
    Last edited: Mar 11, 2015
  12. Mar 11, 2015 at 9:18 AM
    #12
    cr500taco

    cr500taco [OP] Well-Known Member

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    I appreciate it... I tried to program the SC with the Toyota trans code but it never took them...

    On another note, I'm sure the trans temp is fine. When I got home, my gauge said 220. But, I felt the coolant and it was hot, but not hot enough that I couldn't hold the stick.
     
  13. Apr 14, 2015 at 7:36 PM
    #13
    cr500taco

    cr500taco [OP] Well-Known Member

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    Just an update. I got my cooler hooked back up and the gauge reads correctly, now. The cooler dropped the temp about 30*. But the temp still climbs up going up hill and it's hit about 205* with it about 90* or so. But, now it cools down more going down hill than it did without the cooler. Talked to a couple of other people and they said the same as you and my trans guy that it might be the torque converter causing it to run hot. If I do need to replace it, is an OEM one recommended?
     

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