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Transmission is over heating

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by asterix, Sep 15, 2004.

  1. asterix

    asterix Registered Member

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    Need some pointers on what to do. Driving around in the city my transmission will hit 350+. In the mountains it will get so hot that the guage will not even function anymore. Needs some hints into what to look for?

    Bacically i have a 1989 k5, 350 bored .30 motor, 4.56 gearing and 36 inch tires. my transmission does have a aftermarket cooler on it.
     
  2. xtrmjoe

    xtrmjoe 1/2 ton status

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    get a 2nd cooler and a deep pan. I got my fluid capacity up to almost 20 quarts. Deep pan, 2 huge coolers and 2 huge remote mount filters did the trick. Sending unit or guage may be broken I am suprised that is still runs 350 should smoke the fluid. What does the fluid look like? If it really got that hot the fluid has lost its ability to work properly.
     
  3. asterix

    asterix Registered Member

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    i do need to check the fluid /forums/images/graemlins/doah.gif, i have smelled it cooking. i have no carpet and that floor will cook an egg.
     
  4. Thunder

    Thunder 3/4 ton status

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    You need change the fluid and filter that trans ASAP. Also check the coolant lines and cooler to make sure they are not pinched or plugged. There is something very wrong if your tranny is getting that hot. Should run around 160 to 180 max
    How big is your cooler? Where is it mounted? And Are the coolant lines also routed thru the radiator?
    Where is the sensor for your guage located?
    Is the TV cable adjusted right? If it is not the tranny may be slipping bad causing heat build up.
    If you drive it long, running that hot. Your tranny will soon be toast.
     
  5. emoo99

    emoo99 1/2 ton status

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    i'm thinking chunky fluid maybe clogging the lines and not being able to circlulate, change your oil while your at it too.. /forums/images/graemlins/waytogo.gif
     
  6. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    Need some pointers on what to do. Driving around in the city my transmission will hit 350+. In the mountains it will get so hot that the guage will not even function anymore. Needs some hints into what to look for?



    [/ QUOTE ] /forums/images/graemlins/yikes.gifHOLY CRAP! 350* should have left you stranded! Something is seriously wrong, if you are running the lines through the radiator cooler then into the air to oil cooler and back that should be enough to keep it cool.

    Dual air coolers + radiator, dual filters, and a huge pan shouldn't be necessary to keep a th700 cool under the right conditions.

    If the fluid did hit 350* I would first figure out what is wrong and then I would be prepared to have the tranny gone through. /forums/images/graemlins/frown.gif
     
  7. crazy427

    crazy427 1/2 ton status

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    after you check out the cooling system, make sure that lock-up is working. Lock-up being activated completes the cooling curcuit .If lock up is not operating in overdrive the fluid flow thru the coverter and out to the cooler is cut down to 1/3rd of the proper flow. which will result in over heating. also make sure you guage sender isnt close to the exhuast or somthing that will give a false reading.
     
  8. surpip

    surpip 1 ton status

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    The way to check the lock up is when your driving down the road in OD lightly step on the brake if your engine RPM's go up the lockout is working
     
  9. BAJA_BLAZER

    BAJA_BLAZER 1/2 ton status Author

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    I would seriously question the accuracy of your gauge. 350 degrees, or higher if your off the gauge, for any amount of time would have killed your trany and it would be leaking as the seals are not rated to operate at that temp. If you are using the stock cooler in the radiator it would also transfer so much heat to the cooling system that you would over heat. Use a heat gun to check the accuracy of your gauge.
     
  10. 83ZZ502_Jimmy

    83ZZ502_Jimmy 1/2 ton status

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    [ QUOTE ]
    I would seriously question the accuracy of your gauge. 350 degrees, or higher if your off the gauge, for any amount of time would have killed your trany and it would be leaking as the seals are not rated to operate at that temp. If you are using the stock cooler in the radiator it would also transfer so much heat to the cooling system that you would over heat. Use a heat gun to check the accuracy of your gauge.

    [/ QUOTE ]

    I'm also pretty sure that the gauge is wayy off. All those bad things would happen at that temp..
     
  11. asterix

    asterix Registered Member

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    I thought that too. But when it gets hot i feel it in the truck, and it is worse then the the area that is near the exhaust. The hump in the floor becomes so bad that my leg feels like it is burning. Also when the guage does get really hot i can feel the truck loosing power and strugling to go up the hill, the engine is trying but there is nothing to the wheels... I'll try and check the fluid tonight, and check the over drive item that someone had mentioned.

    Brett
     
  12. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    after you check out the cooling system, make sure that lock-up is working. Lock-up being activated completes the cooling curcuit .If lock up is not operating in overdrive the fluid flow thru the coverter and out to the cooler is cut down to 1/3rd of the proper flow. which will result in over heating. also make sure you guage sender isnt close to the exhuast or somthing that will give a false reading.

    [/ QUOTE ]Really? /forums/images/graemlins/blush.gif Jet performance claims running without lock up only raises the temps by about 20*. You are making me nervous because I still havent wired up my manual lock up yet on my built 700. /forums/images/graemlins/crazy.gif
     
  13. Hossbaby50

    Hossbaby50 3/4 ton status

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    Ya, unless your 700R4 was built as a nonlockup then you need to get the lockup hooked ASAP. It is a very bad thing to not have lockup on a 700R4 that is designed for it. You don't get enough cooling flow to the 3-4 clutchpacks I have been told. Get lockup ASAP.

    Harley
     
  14. emoo99

    emoo99 1/2 ton status

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    oh man, i don't have lockup either, i haven't been in OD that much but if that's true i better order a kit pretty soon.
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    I think I believe JET. I know too many people not running lockup for long periods of time without problems. Of course, all run aftermarket tranny coolers.

    OD is already weak, the 700 is borderline undercooled from the factory, and 20* is probably about right for the fluid to go critical.

    Where is the original posters temp sender? Is there a chance that the exhaust (particularly cat converter) is near the sender and influencing the reading? Less power as heat increases in the truck sounds like a converter/exhaust problem.
     
  16. asterix

    asterix Registered Member

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    Not sure where the sending unit is, but i'll try and locate it, i checked the fluid and it is still a nice clean pink/red color with no odor. I'll post up in a bit with some more info.
     
  17. asterix

    asterix Registered Member

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    well i looked and i found a connector with three wires that is on the drives side of the transmission. one of the duals is about 5 -6 inches away and down from the connector.that cat looks decent i know that after the cat is a bend that is really close to the floor and i need to make a heat shield for that.

    Is there a test that i can do to see if the cat is getting plugged or do i have to take it to a specialist. I know that there is a smell like the engine needs a tuneup, maybe running rich.
     
  18. BAJA_BLAZER

    BAJA_BLAZER 1/2 ton status Author

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    Get a Heat Gun and find out how hot things (Transmission, Radiator, Exhaust, etc.) really are. You have gotten a lot of good input here, maybe you need to get some help if you can't figure it out from all of this.
     
  19. dyeager535

    dyeager535 1 ton status Premium Member

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    You measure converter restriction by tapping into the exhaust upstream of the converter. Anything over 4PSI I believe is considered a restriction.

    If you have AIR, you can test from there, and even an O2 bung could be used for that test.
     
  20. Monster

    Monster Registered Member

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    Transmission runs hotter than your engine.
    Engine temp is 210 trans may hit 220 maybe 240 on a hot day.
    Anything over 240 is to hot. Thats what my tranny guy told me.

    My engine runs at 180 my tranny runs 200 on a hot day it may hit 220

    <font color="blue"> </font> 86K5-300hp-hotted-700R4-7"lift-37"bajaclaws-flowmasters-14boltSF-4.11gears-Lots of stereo equipment
     

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