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Busted 700r4

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by riggz, Dec 12, 2006.

  1. riggz

    riggz Registered Member

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    I'm trying to troubleshoot my 700. History on the tranny: rebuilt twice in the past 70k miles. Once by a shady local shop and the 2nd time by Mr. Transmission.

    It seems to make a little whine when shifted into drive from neutral/park. Once in gear it used to drive and shift fine until recently. I was barely able to make it home. After a few weeks i went back out started it up, and was able to drive it down the street and back and then up my steep driveway with no issues.

    After letting it run for about 20 minutes, i pulled it back down the drive and attempted to drive down the street again, but it wouldnt move. it seemd like when i shifted it into gear nothing happened, but when i gave some throttle it made that whining sound again and appeared to somewhat drop into gear.

    I've also noticed that the Service Engine light goes out immediately after engine startup. It should stay on for a few seconds. I was told when i had it rebuilt the first time that this was caused by a bad ECU which i then replaced. Did the ECU go bad and in turn screw up the tranny?

    I guess my question is, is this an issue with the torque convertor, transfer case, or the actual 700r4 itself? I'll be damned if i drop another penny on someone asshat to rebuild the thing only to have it last another 20k miles.
     
    Last edited: Dec 12, 2006
  2. MA87K5

    MA87K5 1/2 ton status

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    What is the fluid level at? I rebuilt mine and I have no problems at all. I beat the hell out of it also. If it does need to be rebuilt again. You should do it yourself. At least you will know what is in it. Should cost you under $500 for good parts. I used the GM Automatic Transmission Overhaul book by Haynes. Worth every penny I spent. With this book anybody can rebuild a tranny. My 1st time rebuilding a tranny also. The hardest part was removing the tranny.
     
  3. riggz

    riggz Registered Member

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    Well embarassingly the fluid was quite low. It wasn't even registering on the dipstick. I refilled the fluid and it appeared to get worse.

    I am debating on rebuilding it myself. What complications did you encounter? Any special tools that would be needed?
     
  4. MA87K5

    MA87K5 1/2 ton status

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    The book has the list of tools, but I used a flat screwdriver, snap ring plyers sockets and a ratchet, torque wrench, a speed handle. I made my own tranny stand. You can use a table but the stand was easier.
     
  5. bigred81

    bigred81 1/2 ton status

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    Start over with a good core it sounds like there might a problem with the valve body and that is one of the worst years of 700R4 to rebuild. Look for 1988-1992 700r4 because it has the improved valve body, redesigned sun gear shell, and they redesign the internals to keep them from shelling out the back end of the transmission. Since it has had repeat failures it would be best to start over with a good transmission. This is my 2 cents worth.

    bigred81
     
  6. roadnotca

    roadnotca 3/4 ton status

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    A surf through BowtieOverdrive, can only help.:D
     
  7. riggz

    riggz Registered Member

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    Thanks for the tool list MA87K5. I figured it would take more than that. Seems like this is something I can tackle on my own.


    Ok, will any 1988-1992 700r4 mate to my 1987 350? Or will i need to get some additional parts/modifications done? Also how can I tell if it's a newer model?

    Would I be better off just buying a rebuilt tranny? I see them go for $500-600ish on ebay w/ a 6month warranty.
     
  8. MA87K5

    MA87K5 1/2 ton status

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    700r4s that came from a V8. To save time then buy a rebuilt one. But shops around here charge $1000 on up to rebuilt. Not sure how the $500-$600 rebuilds will be like.
     

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