Transmission Problems 91 Silverado K1500 700R4

Discussion in 'Chevy Truck Forum' started by Saugeen Drifter, Jan 18, 2011.

  1. Saugeen Drifter

    Saugeen Drifter Senior Member

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    I have lost 3rd and OD in my transmission (obviously if 3rds gone achieving OD is out). I just put this tranny in a month ago, transmission is strong 1st, 2nd, reverse, then it hits 40km (attempts 3rd) and revs like it is in neutral. I pulled over and checked the fluid, dipstick was bare, though to myself, "id better check it again", then it was an inch up the dipstick "what is going on" checked it a third time and its 2 inches above the (hot) mark, hoped in it got up to 80 and again revved like neutral. Pulled over dipstick read add, added 1 liter, let idle for couple minutes, checked it again 2.5 inches above hot with the odd bubble (not frothing) on the dipstick.
    Brief History:
    moneys tight can't afford new/rebuilt so tranny came from auto recycler (km unknown)
    put 1pint lucas transmission additive in
    new filter less than a month ago
    approximately 200km on new tranny fluid/filter
    Fluid is still red and clear but does smell off.

    What am I looking at here? is it because I have a 6" lift, 33's and its -15C (5F) and I'm driving at 40+km and the fluids viscosity is increasing? Is it a solenoid problem; and if it is what solenoids am I replacing and where are they? Is it the additive? Are there any small ports that are known to clog up in these and need to be blown out? Have I dropped the 3rd clutches? Fluid and filter change?

    Need the old girl to keep truck'n.....Any help is appreciated
     
  2. PAPA BEAR

    PAPA BEAR Senior Member

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    sounds like 3/4 clutches the reason i say this i have a 99 z71 with a 4L60e tore down at the shop with the same problem it,s getting a z pac beast shell new bushings.bearings and shift kit
     
  3. Case 7230

    Case 7230 Senior Member

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    there are no electronic shift controls on the 700R4 so you can rule that out. The only thing that is electrically controlled is the torque converter lockup.
     
  4. Saugeen Drifter

    Saugeen Drifter Senior Member

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    My transmission is not a 4L60 (LT) or 4L80 (Heavy duty) they started using them in 1994/1995. I have a 700R4 but I'm sure the construction is the same just without the electronics.
    Will a high level of fluid change any type of pressure settings in the transmissions mechanical shifting or affect the solenoids? Could it cause air locks or siphoning of some sort? I have no frothing occurring.
    Does a higher gear 3/4 compared to 1/2 have a higher demand for fluid flow thru the system? Could it be that the filter is spent thus not allowing flow at higher rpms?
    I am looking for any alternative to swapping this, I parked my truck in my fathers garage overnight and now after checking the dipstick (cold engine) it shows 4inches above the hot mark, after allowing the truck to warm up for 10 minutes it shows 1 inch above the hot mark, after cycling through the gears while applying the brake it remains at 1 inch above the hot mark, took it for a drive. Somewhere between 40 and 60 it it free revs (attempting 3rd gear), came back home and measure the dipstick, no fluid on (2.5 inches below hot mark), waited 15 seconds, fluid level at hot mark, waited 15 seconds more, fluid 1 inch above hot mark, checked 3 more times, fluid remains 1 inch above the hot mark . What the deuce is going on with this thing, I'm sure truck ******* are not visiting and adding fluid. Main reason I am reluctant to swap this is...It's -10 C and I have to do it in my driveway, on my back. Garage would be a great idea but my old man knows as well as I do that not spilling a drop of fluid is not going to happen. My funds are limited and a crate tranny is over 1800$ and a rebuild 1000$, any help would be greatly appreciated. I have never had a transmission do this before, the fluid looks good, smells funky but not burnt (dark fluid or burnt smelling indicates clutches are finished), no frothing/bubbling (indication of fluid too high).
     
  5. Case 7230

    Case 7230 Senior Member

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    But for the fact you have a "Neutral" when it should go into 3rd I would have said you may have a governor problem but I have to agree with PB on the clutches, although I am no expert.
    And -10 degrees C, thats about 12 degrees F, I don`t blame you for not wanting to pull it.
     
  6. PAPA BEAR

    PAPA BEAR Senior Member

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    the over full sounds like converter drain back possible worn stator bushings a clogged filter can cause low line pressure but it is usually clutch material that clogs it Chevy usually puts a magnet in the pan to catch the small medal particles
     
  7. transman618

    transman618 Senior Member

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    The 3-4 clutches in these are known to be weak. Tear it down, put a z-pack in the 3-4's. I ALWAYS upgrade 3-4's in every one of these transmissions.


    transman
     
  8. Saugeen Drifter

    Saugeen Drifter Senior Member

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    Thanks everyone for the information, I had no idea what had happened to the tranny until I took it apart. Looks like the previous owner did some extensive towing of a boat or trailer, 3rd gear clutches were burnt out of it. All of the clutch assemblies were very worn, was just a matter of time before it failed. Also found one of the ball bearings in the throttle body (1/2) had caused fretting in its port, so that may have attributed to it. But I'm pleased to say that a small part of this transmission lives on in the one I just assembled. There really is no end to the fun and challenges we face with these vehicles, just ets us know just how complex they are. Thanks again everyone, Cheers.
     

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