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Transmission Temperature

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by cigar_stub, Mar 14, 2009.

  1. cigar_stub

    cigar_stub New Member

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    In addtion to the tripometer I can select to view transmission temperature on my 2008 Silverado with the 5.3 liter 8 cylinder. Just driving down the highway, without towing anything, I saw it at about 199 degrees.

    My question is: What is normal and at what temperature should I become concerned? Should I expect higher temperatures when towing my boat, in the summer, uphill?

    Thanks for any direction or advice.

    [​IMG]
    Last edited by a moderator: Jun 24, 2013
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  2. dwill3015

    dwill3015 New Member

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    I found THIS SITE that has a chart based on the average temp.
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  3. tbplus10

    tbplus10 Moderator

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    Trans temps will usually mirror engine temps (give or take a few deg.) in normal traffic situations.
    During summer towing a boat they will shoot up some. I know your truck has a trans cooler already but addition of an inline auxillary cooler would be a great addition to keep temps as low as possible. Most auto parts stores sell trans coolers for under $100, this is an item that bigger is better so the largest one you can fit in is a good choice.
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  4. Jimmiee

    Jimmiee New Member

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    Good explanation Tim.
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  5. 1st Synthetics

    1st Synthetics New Member

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    Anything under 220 you are fine. My truck runs around 199 towing my trailer. But if I put it in tow haul mode it drops 20 degrees. My Allison has a trans cooler. If you do have heat problems try switching to a good synthetic trans fluid and it will lower the temp a bit.
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  6. Jimmiee

    Jimmiee New Member

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    To add to the mix make sure you use the correct transmission fluid. I'll throw a wrench into the conversation since we're talking about temperature.

    A transmission can run too cool!

    Many transmissions have a cooler bypass so the transmission fluid bypasses the cooler until the radiator warms up. The reason for this is twofold. First off if the fluid is too cold it wont flow and lubricate properly, and secondly if the fluid is too cold it can't flow through the electronic solenoids fast enough to control line pressure and move the shift valves. Many valves nowadays are PWM controlled. PWM means pulse width modulated. What this boils down to is the pressure control valves are moving in and out at a high rate of speed. If the oil is too cold the transmission will not respond as quickly as it should.

    Ideally the ATF should warm up as quickly as possible and then stay within a few degrees of the coolant temperature. Remember the transmission cooler in the radiator is really a heat exchanger.

    If you live in a temperate climate all of this really is not important but if you drive in real cold weather then it becomes important. Synthetic oil flows better cold so this is another reason why manufacturers are using synthetic blends.

    Jim
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  7. cigar_stub

    cigar_stub New Member

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    Thank you all for the comments. I'll be keeping an eye on the temp going forward.
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  8. nickgiacalone

    nickgiacalone New Member

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    in my 09 2500 if i have no load and am not towing my trans only runs at around 120-140. when i have a load its usually around 200-220. i had mine up to 240 when i was pulling an f-250 <--:lol: to the trans shop. and i know the chevy 2500's that i pull the landscape trailer with at work and plow with, i want to say they run near 250. needless to say the work truck i ride pretty hard, especially since it's not mine and we have a full time mechanic if anything goes wrong.
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  9. kcb37

    kcb37 New Member

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    I would agree your not hot yet. Even at 220 your still good. You really don't want to get over 250.
    If you pull a lot of weight most of the time then another cooler would be good, but if your at like 150 you have to much cooling.
    One more thought, 200 is a good temp to have the trans at just driving around. A little over towing is not bad.
    Last edited: Mar 25, 2009
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  10. setter g

    setter g New Member

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    Was the trans temp monitor an option or standard on your 2008?
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  11. tlperry68

    tlperry68 New Member

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    On the freeway pulling 8.000 pounds while the ambient temp was 107 degrees the tranny temp didn't peg over 220 degrees. Keep in mind I have te Allison and the grades out there were not steep. I find the tranny temp typically ranges about 100 to 150 degrees hotter than ambient.
    If you are pulling through town you can put the tranny in neutral when you are at stop lights, this will help speed the fluid through the cooler and reduce the higher temps.
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  12. 1st Synthetics

    1st Synthetics New Member

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    I do believe it is standard.
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  13. msudmax

    msudmax New Member

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    Hey guys got a quick question to add. I have an 03 6.6 Dmax AT. Just had some work done on the tranny and the shop replaced the old fluid with brand new sythentic stuff.

    Anyways, I was driving down the freeway on my way back to school not towing anything running about 77-78mph. The transmission Temp is running around 160-185 with the grill cover off. At normal speeds of 55-60 with the cover on it runs around 150-160 not towing. This is winter so I dont remember what it was runnng around summer as I just bought the truck in August.

    So reading some of the replys I feel ok, but just not sure. Thanks for any help.
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  14. nickgiacalone

    nickgiacalone New Member

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    my 6speed on the gas motor runs about 110 when its mid 30's out.
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  15. 1st Synthetics

    1st Synthetics New Member

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    Those temps are fine. That is about where mine runs.
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  16. msudmax

    msudmax New Member

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    Thanks for the responses.
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  17. ChevyFan

    ChevyFan Administrator Staff Member

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    This is a good reference discussion for the transmission cooler discussion that we're having in the Towing Forum.

    It is important to note that not all vehicles have the transmission temperature readout, I'm not certain exactly what the code for this is but it does seem to be tied into the AFM system as a pair, but even that might just be a coincidence.
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  18. tbplus10

    tbplus10 Moderator

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    It rings a bell that you mention trans temp being tied to AFM, not long ago I was pulling a small trailer in an area with small rolling hills, a couple things happened at once that left me thinking.
    I was traveling down hill after a particularly long up hill that made the trans temp climb, the truck was running 4 cyl mode and as soon as the trans temp jumped up a little the engine changed to v8 mode going down hill.
    This was unexpected since after 2 years Ive never seen the truck go v8 mode down hill.
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  19. K15 Blazer Guy

    K15 Blazer Guy New Member

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    ive scorched trans oil before in a jeep... climbing a large cinder hill for about a mile lol
    if I ever get another automatic, its getting an extra capacity pan, a temp gauge on the dash, its own big cooler, and probably its own fan too.... a transmission is almost more $$$ than an engine now.
    keeping them cool is what get them to 300,000 miles and beyond.
    #19
  20. steved

    steved Former Member

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    My observations:

    My 2012 2500HD (6spd auto) runs:

    - 160*F unloaded, outside temperature over 90*F.
    - 185*F towing 3k pounds, loaded with roughly 1k pounds, outside temperature over 90*F, and hilly terrain.
    - I have seen 200*F one time, and that was towing at max GCVW in the mountains, outside temps around 75*F.
    - It might approach 170*F if I'm sitting in heavy traffic.

    I rented a 2013 1500 (4spd auto) last week:

    -180*F unloaded at 75*F, highway
    -200*F unloaded at 90*F, highway
    -220*F fighting heavy traffic at 75*F

    Between the two: I'm pretty sure the 1500 did not have a stand alone factory trans cooler, my 2500HD does. And the 1500 would unlock the converter on the highway (pulling a grade) where the 2500 would have either held the gear or would have dropped a gear (converter locked regardless).
    #20

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