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Cheap Fix for a 700r4 to NP208 leak

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TexasK5Blazerman, Mar 29, 2002.

  1. TexasK5Blazerman

    TexasK5Blazerman Registered Member

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    A problem that is common to blazers that have a 700r4 transmission mated to an NP208 transfer case is the forming of a gap between the tranny and the Tcase adapter. The gap forms when too much stress is put on the four 3/8 bolts that attach the transmission to it. The gap widens, and your vehicle begins (and never seems to stop) leaking tranny fluid everywhere. On my truck, I began buying transmission fluid by the gallon. (complements walmart) My first solution to the problem was to heli-coil the holes and retain that 3/8 bolt. However, although the problem seemed to be fixed at first, it soon began leaking again. My second (and correct) solution was to bore out the bolt holes into the tranny to 1/2". This is the maximum size allotted, for you will soon run out of aluminum. Also, the adapter was drilled out to a 1/2" hole. I used grade 8 hardware, and the larger (and stronger) bolts add enough rigidity to handle the force of a really hard burnout without widening (or forming) the gap. A last resort to this problem is a transmission gut-swap (for lack of a better term) and simply get a new housing , but around here that runs about $300: to expensive. Anyway, a cheap and effective way to fix this problem is a $20 1/2" tap set, a $10 drill bit, and about $3 in hardware. Good luck, hope it works for you also.
     

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