91 K1500 Transmission Problem!!!

Discussion in 'Chevy C/K Truck Forum' started by Juicer55, Dec 10, 2012.

  1. Juicer55

    Juicer55 New Member

    Hi everyone i have a question and i am just stumped. i was plowing with my 91 K1500 and it worked great for a while and the transmission start to slip really bad. Then it stop moving the RPM were up but it would not move. i cycled through all the gears PRND12 and it wouldn't move. i turned off the truck wait for five seconds and started it back up and it moved for like a couple of minutes. then it did the same thing. i can keep turning off the truck and it works of couple of minutes before stop working again. i dont know if it is the transmission, torque converter, tranny filter clogged up. if some buddy knows what it is please let me know.
  2. Jamm3r

    Jamm3r Member 2 Years 100 Posts

    There's no way to know for sure without trying stuff.

    If you don't know the service history or if it's been at least 20,000 miles since the last time the pan was dropped you should just go ahead and drop the pan, replace the filter, clean the magnet, and put in new fluid. If that clears it up, great.

    Next possibility is that it might have been overheated. Plowing snow is really tough on the 4L60 transmission you have, and if it's too hot the fluid might have thinned out to the point where the line pressure dropped and the clutches won't stay engaged. You can measure the pan temperature with an IR temp gun, if much over 200 you should think about adding auxiliary cooling or adopting a more relaxed technique when plowing.

    If it's not running hot then you probably have a valve problem. Usually these can be fixed without pulling the transmission but I've never done it.
  3. Revredneck

    Revredneck Rockstar 100 Posts

    It sounds like you broke something inside there. Most likely, you're looking at a major overhaul. Sorry to be the bearer of bad news.
    Good Luck and God Bless
  4. JTward1

    JTward1 Rockstar Gold Member 100 Posts

    I just had my 1990 700R4 rebuilt, Great local shop. He quoted me $1400 to $ 2000 depending on how many upgrades or modifications dictated by GM over the years. Turned out to be $1495, $1565 with tax. Mine was doing what your's has done and my problem was the forward clutch pack just froze up. Now that's it's done it feels like a brand new truck. Word of advice, if your plowing or towing never drive it in 4th gear or the over-drive as it will cause the transmission to overheat, even if like me, you have an external trans cooler. I have a Hayden that's 12"X15", which is about as big as they come. :lol:

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