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More Trans Questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by RLBstein, Feb 7, 2001.

  1. RLBstein

    RLBstein 1/2 ton status

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    I have a 700R4 with a 6.2l diesel and 10 years ago i burned up the transmission when I ran out of coolant. I took it in to a shop who charged me my life savings (I was 17) and said he would install a trans cooler. When I took my truck completely apart to rebuild the entire truck I noticed that a pair of transmission lines already run into the radiator. And there was is a small oil cooler in front of the radiator and now that i've finally got the entire truck back together, I don't have a clue what oil lines are supposed to go to that cooler they installed 10 years ago. Why would I need another trans oil cooler if my lines already go through the radiator, and where would they plug in anyways? I was thinking maybe it was to cool the engine oil, but those also run through the radiator for cooling. The only oil not running through the radiator is the power steering. I can see where that might be possible because the power steering pump also runs the power brakes. Sory for the long story but i'm just confused. Thanks for any help.

    82 Blazer
     
  2. HarryH3

    HarryH3 1 ton status Author

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    The tranny fluid goes through the cooler in the radiator (which can't get any cooler than the engine coolant itself) and then goes through the external cooler. This removes more heat before returning the fluid to the tranny.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    I should know this by now, almost all GM auto trannies are the same...you want the fluid coming FROM the tranny (top line I'm almost positive) which is hot, to go first to the radiator. Top fitting. Then from the bottom fitting on the radiator, you want it to go to the auxiallary cooler.

    You don't HAVE to run the lines this way, the tranny cooler in the radiator isn't very large, (smaller than any aftermarket cooler you typically see) and since it is in the radiator, as stated, it can't go below engine coolant temp. Just running the lines to a large auxiallary cooler should be enough, but the increased capacity and cooling of using both, IMO, is the best bet. Make sure to use REAL good hose for the connections, i ahve had teh tranny line split that went to an auxiallary cooler, and it was spraying tranny fluid right on the manifold..i was lucky I didn't have a fire.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  4. CaptCrunch

    CaptCrunch 1/2 ton status

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    Top line is right... But I have heard a couple different ways to hook in a cooler... rad first like has been stated, but then I have heard cooler first then rad because in colder climates it can get too cool. Is there such a thing? Running it through the radiator keeps the trans fluid at a med temp when the trans is working hard. This is just something I've heard. Would like to hear anyone's opinions on it...

    1987 Chevy K5 Blazer- 350 TBI
     
  5. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    The cooler in the radiator is much more efficient because it is a liquid to liquid cooler. Always use them both and put them in series as stated above for best performance.
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    I was told locally (WA state, pretty mild climate) that there is no way you can overcool an auto trans, especially here. There has to be a minimum, but I'm not aware of it. That brings upa good point about running it through the radiator then..the engine is "governed" for 195, so if the tranny tried to run under that, it would be picking up heat there. You'd have to put t temp gauge on the tranny to see what kind of temps youa re running though to be very accurate.

    Dorian
    My K5 and Chev/Olds tech/links page: <A target="_blank" HREF=http://www.dorianyeager.com/index2.html>http://www.dorianyeager.com/index2.html</A>
     
  7. HarryH3

    HarryH3 1 ton status Author

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    Mine's installed so the aux cooler is in line after the cooler in the radiator. If the engine's running hot I don't want to make the tranny fluid hot again by forcing it back through the radiator after it's already been cooled by the aux cooler.

    Is there such a thing as "too cold" for a tranny?

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  8. balzer

    balzer Registered Member

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    i dont know if this has anything to do with what yall are talking about, but i just had to tell somebody and it is about a 700r4. about a month ago i did some pretty bad a$$ 4-wheelin (mudding). and a couple days later it started making some HORRIBLE whinning noise, and not wanting to shift, but anyways, i still drove it for a week after that doing the same thing. i checked the fluid in it, but i thought my stick was reading wrong cause i never saw any fluid on the stick. i would have thought that it was leaking if i had seem some fluid on the ground but everywhere i parked was spottless. needless to say about a week and a thousand bucks later the transmission guy showed me the whole in the old case that you could fit your hand in. i had been driving it to school and back complety dry and the huge hole in it. i didnt see any fluid cause it had dumped it all out that day in the mud when i went mudding. but it was compeltly worth it!!
     
  9. CaptCrunch

    CaptCrunch 1/2 ton status

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    Wow! I wonder if it looked worse then mine... pulled the pan, never seen so much clutch, metal, and band fragments...

    1987 Chevy K5 Blazer- 350 TBI
     

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