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VERY interesting shift problem w/700

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by txbartman, Jun 28, 2001.

  1. txbartman

    txbartman 1/2 ton status

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    I had been having problems with my 700R4 not wanting to stay in overdrive (4th) at higher speeds. With even the slightest load like going up over an overpass on the highway and with the throttle consistent and maybe even reduced some, the 700 would shift down into 3rd for about 2 seconds then shift back up. It would stay in 4th for about 10 seconds and then do this "hiccup" shift again. It would even do it on a flat road with the slightest head wind. It made it where I had to drive in Drive most all the time about 40MPH which ate gas and sucked.

    Well, last night I dropped the pan to change the fluid and replace the filter. Of the 10 pints that were supposed to be in there, only about 5 were drained (about 3 pints in my drip pan and 2 on the driveway). The truck had been sitting for a while and only used intermittently. This was something on my list to service but had not been done or checked yet.

    After changing the fluid and filter and putting a full 10 pints back in, everything worked great again. No more hiccup shifting. I believe the transmission was simply getting way too hot without enough fluid and this was causing the problem, even with a tranny cooler.

    Just an FYI from my experience.

    85 GMC Jimmy, 305 w/TH700-NP208, 4" lift, 32X11.5 BFG ATs, 15x10 Eagles, Smittybuilt tube nerf bars and bumbers
     
  2. newyorkin

    newyorkin 1 ton status

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    The torque convertor was holding half the fluid!!!!! You may be overfilled now, which will airate the fluid and make it stop cooling and cleaning. Check your level when hot, and if overfilled: Crack open one of the cooling lines, have someone start the engine (make sure they can hear you when you say Stop, and bear in mind some fluid will continue to flow after the pump stops as it depressurizes), and drain about 2 or 3 quarts of that $2.50 a bottle liquid gold, then drive your truck for about 15 minutes and check the fluid (in park, engine running, level ground).

    Too much fluid also creates a higher pressure inside the tranny (fluid has no room to go anywhere). I don't know specifics of the effects it has on the internals, but like overfilling your engine, it can't be good. It will more than likely blow out your dipstick and spray from there, or a seal.

    No matter what you do, you will almost never get that fluid out of the torque convertor without removing it from the truck.

    It's very tedious, but when swapping ATF, you have to check the level before you do the job (maybe the day before so you're not changing too-hot ATF), then when you're refilling (after draining), replace what you took out, plus whatever you may have been down. Then drive it and check it again...
    Of course, if you know exactly what torque convertor you have and it's capacity, you can fill the tranny to that level minus the torque convertor.

    BTW, this shift oddity is a pretty common thing for the 700R4. I've had it in every 700 I've driven, even right after rebuilds and in perfect condition. There are companies that build a bolt on shift kit to eliminate it, but I believe it occurs intentionally to reduce the load on the tranny. I'd bet the head wind was more than you felt, or there was a slight incline you weren't aware of. If you notice, you probably had to finesse the pedal to get it back into 4th. I'm not sure why yours went away with a fluid change. Maybe a result of over-filling? I'm not a tranny guy, but I've blown apart a lot, so have learned a lot.

    But then you could be right in the first place, low fluid!

    Good luck!! Hope I helped!

    Ratch
    **<A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A> What more is there to life?**
     
  3. CaptCrunch

    CaptCrunch 1/2 ton status

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    Yeah check to make sure your tranny is at the right level of fluid. The converter and lines hold quite a bit. In terms of the shifting problem there is a valve B&M and TCI make to solve the problem and help you keep in OD. You will need to drop the valve body out to replace it. Also make sure the TV cable is adjusted properly... this will cause shifting problems as welll as wreck the tranny.

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <A target="_blank" HREF=http://www.geocities.com/milnerlives_2000/blazer.htm>http://www.geocities.com/milnerlives_2000/blazer.htm</A>
     
  4. Thunder

    Thunder 3/4 ton status

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    newyorkin. The guys said PINTS not Quarts. he put in 10 PINTS thats 5 quarts which is the recomended ammount for the fluid change.
    He did everything ok.
    I think low fluid was the problem.
    Oh yeah. The easist way to remove excess fluid from the tranny is to get a 12.00 fluid pump from a auto parts store. You just stick the tube down the dipstick tube and pump away. It is also a good thing to do before you change the fluid it saves a big mess in the driveway.
    <font color=orange>GOT HORSEPOWER?</font color=orange><P ID="edit"><FONT SIZE=-1>Edited by Thunder on 06/28/01 09:52 AM (server time).</FONT></P>
     
  5. newyorkin

    newyorkin 1 ton status

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    oops! Sorry! In the back of my head I was actually thinking, "If he put ten quarts in, that thing would be leaving a trail down the highway". Duh. Thanks for the correction thunder.


    Ratch
    **<A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A> What more is there to life?**
     
  6. 84_Chevy_K10

    84_Chevy_K10 Banned

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    A flush is better, but you don't always have the machine and it's a pain to do it without the machine.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  7. txbartman

    txbartman 1/2 ton status

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    You guys had me starting to panic!! I thought I did what it sasid in my Chilton! And I checked the level afterwards, it seemed okay. I was afraid maybe I didn't let it heat up enough or something. I was afraid after work I would have nothing but a puddle under the truck (like my driveway)! Whew. I feel so much better. And, just for info, I bought a gallon of ATF Dexron III (3.78 liters) from Walmart for only $4.75. Has worked fine in my Trans Am so I figure it will do well in my toy, too.

    85 GMC Jimmy, 305 w/TH700-NP208, 4" lift, 32X11.5 BFG ATs, 15x10 Eagles, Smittybuilt tube nerf bars and bumbers
     
  8. newyorkin

    newyorkin 1 ton status

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    Very sorry again! I'm feelin' guilty over writing such a massive post anyway...
    Tim is right, (and I plum forot about it) if you can find a shop with the right machine, a flush will blast thru your tranny and clean it real good. For the 2 million cars and trucks on LI, I haven't yet found a place with the machine here... Guess that's cause there are 1 million tranny shops...

    Sorry for the panic alert earlier!

    Ratch
    **<A target="_blank" HREF=http://k5.8m.com>http://k5.8m.com</A> What more is there to life?**
     
  9. Twiz

    Twiz 1/2 ton status

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    Friggin' metric sys. I was thinking the same thing newyorker was! -As a matter of fact, my first thought was, "damn, how'd he fitt 10 qts in that thing?"-

    In the future, too any poster, Wait for a couple of replys to show up, and then "freak out" if needed. Sometimes we all make the wrong call on a problem, but on this board, someone is usualy quick to correct. We are all looking out for each other. Very cool!

    Twiztid
     
  10. DMK

    DMK 1/2 ton status

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    Whats the metric system have to do with anything?
     
  11. Twiz

    Twiz 1/2 ton status

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    Yeah it ain't the metric sys--- doh. Just used to qts. Well thats what I was sayin' in the last half, quick to correct.

    Twiztid (what the hell was I thinkin')
     

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