Transmission Temperature

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

  1. cigar_stub

    cigar_stub New Member

    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.

    Last edited by a moderator: Jun 24, 2013
  2. dwill3015

    dwill3015 Epic Member 5+ Years ROTM Winner 1000 Posts

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

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    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.
  4. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    Good explanation Tim.
  5. 1st Synthetics

    1st Synthetics Epic Member 5+ Years 1000 Posts

    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.
  6. Jimmiee

    Jimmiee Epic Member 5+ Years 1000 Posts

    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.

  7. cigar_stub

    cigar_stub New Member

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

    nickgiacalone Rockstar 100 Posts

    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.
  9. kcb37

    kcb37 Member

    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
  10. setter g

    setter g New Member

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

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