Seeking opinions on adding an external tranny cooler in addition to the radiator
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Northstar Engines and System Technical Discussion Discussion, Seeking opinions on adding an external tranny cooler in addition to the radiator in Cadillac Engine Technical Discussion; Seeking opinions on adding an external tranny cooler in addition to the radiator. I am wondering if there is any ...
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    jimsbox is offline Cadillac Owners Enthusiast
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    Seeking opinions on adding an external tranny cooler in addition to the radiator

    Seeking opinions on adding an external tranny cooler in addition to the radiator. I am wondering if there is any inherent reason not to. Is it likely you could overcool the fluid and damage the tranny (4T80E).

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    Submariner409's Avatar
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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Quote Originally Posted by jimsbox View Post
    Seeking opinions on adding an external tranny cooler in addition to the radiator. I am wondering if there is any inherent reason not to. Is it likely you could overcool the fluid and damage the tranny (4T80E).
    Remember that the existing transmission cooler keeps the fluid at coolant return temperatures - way below 200 degrees but still warm enough to cook off condensation and oil vapor, and the fluid is not subjected to anything close to the damage that engine oil receives - one reason why transmission fluid easily goes 100,000 miles, no problem.

    Unless you're setting up to drag race every weekend, pull a boat trailer or 3,000# camper, an extra cooler is not even close to necessary, especially in a DHS - the 3.11 final drive insures a calm, sedentary transmission speed on the highway.

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    jimsbox is offline Cadillac Owners Enthusiast
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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Thanks Sub,

    I agree, I am going to drop that idea.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Quote Originally Posted by jimsbox View Post
    Thanks Sub,

    I agree, I am going to drop that idea.
    .......here's one for ya': Cooling fans go to FAST at transmission fluid temps of about 302 degrees ! Figure that one out. If anyone in here would know why, it's JimD.

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    jimsbox is offline Cadillac Owners Enthusiast
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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Sub,

    Obviously the coolant won't be at 302 but the thinking may be to increase the efficiency of the radiator to draw more heat away from the transomission fluid.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    A 302 degree trans fluid passing through the radiator side tank will obviously transfer that heat to the coolant and cause the coolant temperature to increase and I would guess, pretty rapidly. I suspect that may be the reason, not to mention as Jim said above, I would guess that there is a limit to the temps they want to see in the trans and 302 might just be it.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    I added an external transmission cooler when the original trans lost TCC lockup. I live in Phoenix where daytime highs are commonly 110+ in the summer, and with no TCC lockup, I'm sure there was some more heat being generated than expected when the trans was designed. Since that time, I have replaced the trans with one that has a TCC that works as designed, but I left the cooler on - I think it can't hurt in my climate.

    I tried to fit a cooler on my wife's 2004 Grand Prix GTP, but couldn't find an easy/good way to route the hoses and mount the cooler, so I decided to pass. Trans fluid temps are displayed on the Driver Info Center, they are frequently in the 230-240 range in the summertime, and the fluid does turn to a reddish brown color, so I drop the pan and refill with fresh trans fluid every year or so. I've been using the Dexron III called for in the owners manual, and which I already had - maybe the Dexron VI would be better. She's gone only about 60K miles, but no trans problems so far.

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    Re: Seeking opinions on adding an external tranny cooler

    Greetings and apologies for posting on an old thread. I too have a failed TCC and although the transmission seems to work fine in my 2001 DeVille I was wondering about adding the external cooler to correct some of the overheating that the slipping creates.

    Has anyone added a cooler like tateos did? If you are looking tateos, how long did you run the first transmission, do you think the cooler helped?

    Regards

    Republic

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Click on Tateos (in blue letters) and you can send him a private message ( I think you may have to make 10 posts to the forum first)

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Republic, If your worried about increased temperatures due to slippage you might want to consider changing from Dexron III to Dexron VI. The Dexron VI is synthetic and fully backwards compatible with Dexron III.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Thank you both. The car drives flawlessly but has not been more than 400 miles from home since the code first occured. I am planning a trip to Arizona, about 1500 miles, and would really like to drive the DeVille. It is the most comfortable and economical in my fleet. I will look into the synthetic fluid. I had not considered that as an option. Again thanks and regards.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    The "slipping" does NOT create extra heat in the transmission fluid. If the TCC is stuck off then the torque converter operates exactly like 95% of all other vehicles without a TCC feature. There is NO reason to add external coolers unless you intend to tow large trailer loads or race the car. The internal radiator cooler is perfectly adequate for the job, and the transmission is supposed to run at over 200 degrees in order to boil off contaminants and moisture in the fluid. The transmission fluid temperature alarm goes off at 304 degrees - yes - 304.

    Change to the new (2006) DEXRON-VI fluid - it's now standard maintenance fill/exchange on all GM vehicles.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator


    The slippage will be minor and of no consequence.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Thanks for the replies. I was just looking at maintenence receipts for the last trans service. 20K miles ago the garage (not GM) installed a filter and Dexron III along with a quart of Lucas transmission treatment. I believe their logic was that without the TCC woking properly the additive would get rid of slip. I've heard more bad than good about Lucas. I'll be changing the fluid (Dex VI) and filter this week. Can't imagine what crud will be in the pan.

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    Re: Seeking opinions on adding an external tranny cooler in addition to the radiator

    Quote Originally Posted by republic View Post
    I'll be changing the fluid (Dex VI) and filter this week.
    Don't bother with the filter... it's only accessible during a transmission overhaul. Most parts counters will sell you something they call a filter... but it's only the 2 pick-up screens that are accessible when you drop the pan. There's no need to change these unless one of the screens is ripped... you'll see what I mean when you drop the pan... don't bother with a pan gasket either... it's reusable and very expensive.



    The filter inlets is where the screens connect. Also pull the hidden drain plug to drain additional fluid.

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