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'91 K5 - 700R4 Tranny will not shift up, only have 1st and reverse - UPDATE: TV issue

Discussion in 'The Garage' started by renstyle, May 18, 2009.

  1. renstyle

    renstyle Registered Member

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    Well finally got all of the bad fuel out of the tank. Got a '91 K5 with 350TBI. I'm still checking on the tranny type, looks like a 700R4 (it is stock).

    I was able to make a short test drive about 5 mi with no problems, max speed 55MPH.

    As I was heading home I tried shifting down to 3, then 2, finally 1. I was going very slow (less than 15MPH). Each shift down "felt" normal.

    Now I find that no matter where I shift the tranny will not shift up out of 1st. Only pushed it to 20MPH, no more.

    Shifting into reverse and 1st is fairly smooth, a slight clunk, satisfying, not scary sounding. No slipping noted when moving in either gear. The fluid at the stick looks clear and pink.

    I've been waiting for a nice, dry day to get the tranny filter swapped out and new fluid. Got 5 QT of Dextron-III and a quart of Tranx-X. The guy at the shop told me you may get 5-5.5 QT of fluid swapped out, so watch the dipstick like a hawk.

    I've never pulled the pan off a tranny before. I've tried cleaning the outside of the housing (no leaks) with a lint-free cloth and tried to make the rest of the pan area as clean as I can get it before I pull it off.

    I've been advised to torque the nuts 20ft/lb once the pan it back on, and to make doubly sure the gasket on the old filter comes out, or use a small pick to make sure it gets removed.

    Do I need to worry about the little metal ball bearings floating around in the pan? Apologies if this sounds like a dumb question.

    Anything else I can check while I am down there? The shift-linkage "looks" ok, but to my inexperienced eye (and ear) I could very well be missing something.
     
    Last edited: Aug 28, 2009
  2. Fabrimacator21

    Fabrimacator21 1/2 ton status

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    Does it feel like it's shifting when you go from 1st to D?
     
  3. 79chevyk10

    79chevyk10 1/2 ton status

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    I understand from your above post that you are not that knowledgable about transmissions so bare with me.

    I assume that during your initial test drive that it shifted into all gears at normal shift times (i.e. 1st thru 4th with TCC lockup felt). As you manually down shifted thru the gears is when the problem started? Or sometime after that?

    You state that it has reverse so we can rule out a broken reaction sun shell (a commom part to break on a 700R4 that will cause no reverse, 2nd or 4th gears)

    I would start by looking under the hood and make sure the TV cable is attatched to the throttle body (the cable that is below the throttle cable, as you apply throttle the TV cable with become longer opposite to the throttle cable).

    Just a note here: There are two pressures that dictate when a 700R4 shifts. Throttle Valve pressure (TV pressure) and Governor pressure. As you apply throttle the cable is pulled and moves the throttle vavle cable inside the valve body increasing TV pressure. At the back of the trans there is a governor valve that is driven off the output shaft. As speed increases the governor spins faster off the output shaft. Once the governor pressure exceeds the TV pressure the 1-2 shfit valve is able to move directing pressure to the 2-4 band servo allowing a 2nd gear shift. The relationship between the TV pressure and governor pressure remains the same for all upshifts.

    Make sure the TV cable is attatched. If it is, pull on it to make sure that it did not break. You should feel a "spring back" feeling when you pull on it. Make sure it doesn't feel like it is binding.

    If above checks out okay, then another common cause for a 700R4 to not upshift is a broken/siezed/worn out governor.

    On the pass. side towards the rear of the transmission case is a dome looking cover. Remove the cover (cover is pressed in, no clips or bolts) and pull the governor out. Look at the green plastic helical gear for wear or stripped teeth. Also check to make sure the vavle inside the governor (you can see the vavle between the windows of the governor shaft) move freely and next make sure the weights and springs at the end are not broken or missing.

    If it turns out that it is neither the TV cable nor the governor, than you have internal transmission failure that will require removal and overhaul of the transmission.

    Good luck

    Aaron.
     
  4. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I broke the sun shell in my 700R4 and i still had reverse and 1st but no 2-4.
     
  5. scooter122983

    scooter122983 1/2 ton status

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    One thing that wasnt discussed was adjusting the TV. To do this there is a adjuster on the bracket that holds the TV cable and throttle cable. This adjuster has a button on it. You may need a screwdriver or such to get to push this button. Push the button and slide the adjuster sleeve all the way up into the adjuster and release the button. Now go in the cab and depress the skinny pedal all the way to the floor. You should hear a a sound like a zip tie. If you dont hear that sound then you probably have a problem with your adjuster in which case you will need a new cable.
     
  6. 79chevyk10

    79chevyk10 1/2 ton status

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    Impossible. The reactions sun shell is meshed to the rev. input drum and then splined to the reaction carrier sun gear. They always break at the splines or strip out at the splines. The 2-4 band clamps and holds the reverse input housing from spinning. It is all splined/meshed together. You lose the sun shell it is impossible to have any one of the gears.
     
  7. renstyle

    renstyle Registered Member

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    The manual downshift felt like it performed normally, each successive shift down allowed the engine to "wind up" with the corresponding lowering of intertia (dunno exactly how to explain, but it felt like a totally normal downshift). It was at this point, when I tried to shift back to (over)drive that I realized that I wasn't shifting up out of first. Took a while to get home at 7MPH! :(

    Others have mentioned the sun shell, and the fact I have reverse is a good sign! :laugh:

    Maybe another n00b question here, but better to test this linkage with the engine running? no? doesn't matter if you're not moving? :confused:

    I will assume again this test should be done at the throttle body connection under the hood? This should be obvious once I roll back under the truck, the other end of the cable prolly just runs into the tranny...

    This again I assume will be more evident when I remove the cover. Never having seen an actual governor (tho I do have some idea of how it works), I'll check for those weights and springs. Would taking a pic with the cover off and posting help to diagnose here?

    Thanks for all of the great suggestions! Very clear and concise. Would you recommend I hold off on the fluid/filter change until after checking all of this or does it matter? I've already bought the supplies and can eat the $30.00 I paid for it all even if the tranny is bunk.
     
  8. renstyle

    renstyle Registered Member

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    Thanks for the tip! If all of this goes south would you have a good rec for a replacement tranny in the central Iowa area? As much as I'd love to try a rebuild myself I certainly am not up to to the task in the near future.

    I'd be willing to consider swapping the tranny myself if I can find a good replacement. Got somebody to give me a hand and some experience with a swap. What does a used (prolly untested?) 700R4 go for these days? I'm hoping not much more than 500-600. Just need to get this truck moving more than anything else right now.
     
  9. scooter122983

    scooter122983 1/2 ton status

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    Unfortunately im new to IA. I moved here in Dec 07 and dint get back into the offroad world until this Feb. You could try Smittys in Des Moines. A guy at work got a Chrysler 12 bolt for a 02 Dodge for about $700.
     
  10. renstyle

    renstyle Registered Member

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    Just called Smittys, they have a trans from an '88 C1500 with 160,000 miles on it for $400. At least it gives me a baseline.

    Thanks again!
     
  11. Fabrimacator21

    Fabrimacator21 1/2 ton status

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    $400 for a tranny with 160k? :screwy:

    Look around on the internet. Should be able to get one with 50k on it for 4-5 hundred.
     
  12. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I was incorrect. I talked with my trans guy and he said a broken sun shell you will lose reverse, 2nd, and 4th. He did say that the OP problem is either a stuck or broken governor, or a stuck throttle valve. He said the first thing to do is to pull on the TV cable a couple times and then see if your problem goes away, next would be to pull the governor and inspect it.
     
  13. renstyle

    renstyle Registered Member

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    Yea, I did some quick looks at craigslist and found some there for as low as $100 in my area. Untested of course, and prolly not setup for a 4x4 truck, but still quite a bit lower than above.

    I've found some good pics of the TV so I've a fairly good idea of what to check, and the suggestions above for setting the TV.

    Regarding the question of the governor. Since this rig isn't going to be rock-crawling anytime soon, and replacement governors are fairly inexpensive, would it be any advantage to me to replace the governor if it looks anything other than pristine?

    I've only had this truck a few months, majority of that it sat in the snow waiting for me. :) I realize with a replacement governor the shift points could be "off" slightly compared to the one that has been riding in the trans for a while, any kind of pre-installation adjustment aside from making sure the teeth are good and the springs/weighs look OK?
     
  14. 79chevyk10

    79chevyk10 1/2 ton status

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    All of which I already stated.
     
  15. 79chevyk10

    79chevyk10 1/2 ton status

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    I would definetly hold off on doing the filter and pan gasket. It just may turn out to be a waste of money and time. A filter change seldomly ever corrects a transmission problem.

    I also assumed that due to the sudden nature of the problem that it was most likely not a misadjusted TV cable, but it may be a good idea incase the adjustment assembly somehow stripped out.

    All TV cable checks and adjustments are down at the throttle body when the engine is off.

    The governor is the only thing behind that cover. Simply pull it out. It will want to spin as you pull out, this is a good side due to the helical gear meshed with the output shaft which also has a helical gear.

    You will need special tools and a working knowledge of transmission in order to rebuild a 700R4 successfully.

    If you lived in California in my area, I would be happy to rebuild it for you (I'm a tranny guy, been building auto trans for 10 years now).

    Also, I do not recommend purchasing a used 700R4 unless you drove the truck it came out of. Unless of course you like flat backing transmissions in and out until you get a good one.

    Again, good luck

    Aaron.
     
  16. 79chevyk10

    79chevyk10 1/2 ton status

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    Yes, good idea to just replace it if you are unsure how to inspect it. As you said, they are cheap. Also, they are plug and play. All shift points are done with spacer plate/valve body.
     
  17. renstyle

    renstyle Registered Member

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    Gotcha, I'll check the TV and governor first, see if that goes anywhere. I feel somewhat "dirty" having the POs trans fluid in the rig. I have no idea where it has been or how long it has been in there. (This was a local truck for duck hunting and the like, hasn't been seriously banged up on the undercarriage).

    I changed the oil out the day after I brought it home. It wasn't awful, but it did need to be done. The peace of mind was worth it!

    Point taken and understood, will check the more obvious bits first, see if this thing will roll.

    I've found some nice pics of this assembly online. I was relieved when I could remember seeing this under the hood recently (was checking the TBI during my bout with water-laden fuel)! :laugh:

    Going to pick up the governor tonite, only $21.00 at NAPA! :laugh:

    Maybe I should try to pick up a dead 350 or 700r4 and just pull it apart for kicks? Find out exactly what all this fuss is about... :wink1:

    That's a kind offer, I do appreciate it. :bow:

    That's always the quandry isn't it? If you don't have the know-how (or a good buddy nearby with it) and you lose a tranny, it's slim pickins. I'm so green in the heavy repairs, but I'm chomping at the bit to never have to be at the mercy of somebody else in that way ever again! :D

    Thanks again for the detailed reply! I'll let you know how this works out.
     
  18. renstyle

    renstyle Registered Member

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    Got this working!

    Finally got the TV cable "set" as per the great instructions found here and links to elsewhere.

    I am able to shift! Even have overdrive!!! :D

    There must be some finesse needed to get the cable adjusted 100%. If I take off gently my shift points are about 1-2, 18mph, 2-3 28mph, 3-OD 45ish.

    If I try to hammer on the throttle I can almost always get the TV to stick again leaving me in 1st only. Then I have to get out, pop the hood and twiddle the TV cable (I tug gently and hear it click at the tranny). Jump back in and good to go again.

    I'm fine with driving nicely when I need to get somewhere, but wasn't sure if I was doing permanent damage by having to mess with this cable every now and then.

    I need to get under the truck to clean off a few years of caked on gunk, the black plastic cable jackets around most of the cables are falling away as dust when I touch them. Could some of this "gunk" be causing a problem where the TV cable enters the tranny itself?

    Thanks again for all of the help, I wouldn't have been able to do this without you! :o
     
  19. 79rustyk10

    79rustyk10 3/4 ton status

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    dont leave it that way for long, the 700r4s need the tv cable adjusted correctly to keep from burning up.
     
  20. Kenny78

    Kenny78 1/2 ton status

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    Sticking after heavy throttle is what mine likes to do. A new cable/ tv cable seal and a filter change alleviated my problem for the last several months.
     

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