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Thread: Cold fluid/sticky valvebody? AOD shifting odd only when cold

  1. #1
    Member ZackN920's Avatar
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    Default Cold fluid/sticky valvebody? AOD shifting odd only when cold

    So, with it getting colder (40s-50's)in the mornings I noticed that the transmission is *sometimes* shifting odd until it warms up. It only does this when I'm light on the throttle too. If I drive how I normally drive durring the day it operates a little more normal, but I try not to be hard on it when its cold.

    So, I noticed if I'm light on the throttle coming from a stop, when shifting out of 1st it acts as if it goes into neutral for a a second or 2, then clunks (usually jerks the car a bit) into 2nd gear. Only does this when cold and it doesn't do it all the time. I have never had it happen when i was accelerating moderately. Usually only happens on a road to work with a 25mph speedlimit. I did have it do it again today and its as if it went into neutral, engine revved up a bit then BANG- 2nd gear.
    Once things warm up some and the temp gauge is up a bit, it acts normal. No matter how I drive.

    Is this an issue with a gummed up valvebody? The trans doesn't slip in any gear. It even holds fine on the highway in OD. so I wouldn't think itd be a clutch problem.
    I have no clue how old the transmission fluid is or how many miles are on it. I think I would only count on it having 1 fluid change in its life. Currently the car is at 99,61x miles.
    It does look ok- red in color and I don't think it had a smell to it. Been a little while since I checked it last.

    So- whatcha all think? Hopefully something simple. Btw, what do these old AOD transmissions use for fluid? Mercon/Dexron atf?
    1987 Lincoln Town Car Signature Series-98k miles- LOPO 302, AOD, open 3.27, Dual exhaust w/ Thrush Turbo mufflers

    the others...
    1926 Dodge Brothers Business Sedan- 212ci I4/3 speed/crank start
    1987 Dodge Dakota- 3.9/A999/3.90/2wd (storage)
    1990 Jeep Grand Wagoneer-AMC360/727/NP229/3.08/2" lift(daily)
    1994 GMC Burban L05 350/4L60e/241/3.42
    2001 Jeep Cherokee 4.0/AW4/231/3.73 (limbo)

  2. #2
    all the CFI are belong to me
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    The AOD originally spec'd GM Dexron II. After the Mercon spec was created (which is compatible with Dexron III), that became the preferred fluid for the AOD. Mercon V can replace Mercon, but there is not any compelling reason I know of to change to it. We do not have torque converter clutches so that particular benefit of Mercon V will not apply.

    The symptom you describe is very similar to something I've seen with a couple of my cars, only in cold weather. They will drop into some sort of neutral-like state when decelerating to a stop after a short drive, like pulling out of a driveway and driving only a few hundred feet to a stop sign. It only happens on fairly cold days and only before things warm up. I found that by increasing TV pressure, I was able to reduce how often it happens. I stopped winter driving my cars so haven't explored it more than that.

    All of my cars that have shown the symptom have had fluid and filter changes in their time with me. I run generic Dex/Merc.

    83 GM 2dr POTM 10/2019 | 84 TC POTM 1/2017 & 4/2019 | 85 CS | 85 Ranger +trlr | 86 GM | 91 GM POTM 12/2017 | Junkyards
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  3. #3
    Wagon Addicted Tiggie's Avatar
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    This is the problem I have with my 88. I stopped driving it because it got to be dangerous.

    Really push it warmed up and try to get a 3500-4000 rpm 1-2. A good stock AOD will hit 2nd HARD. A bummed one will slip and slide it’s way from 1-2. The clutches and/or bands are weak in the latter in my untrained opinion.

    I read that the low-reverse accumulator had something to do with that 1-neutral-slippery-when-cold-2 shift but I replaced mine over the COVID and it didn’t help. Mine has 247k on it, though.

    Edit: my valve body was exceptionally clean. Yours might not be. You can pull it out and check the parts that control 1-2 to see how freely they move, trash, or burs. I have a diagram somewhere I can pull out.
    Last edited by Tiggie; 10-18-2020 at 10:57 PM.

  4. #4
    Member ZackN920's Avatar
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    Thanks for the quick reply.

    So, DexII was recomended? Hmm. Seems most of my cars spec that stuff. Too bad they don't make it anymore. Ok then, when I do a fluid and filter change it'll get the DexIII/Mercon stuff.

    Yea, that's something I forgot about in my post. My dad told me about a time recently when he took the car out that it did like you mentioned. Drove fine to the first stop light but dropped to neutral and then revved a bit upon take off until it klunked into first. No problem after it did that on him that day.

    I'll add this for reference, not too long after I got the car- I put a new metal tv cable bushing on and I tightned the cable up a bit. Mainly so it wouldn't want to shift into overdrive so early. I really don't want to tighten it up much more because it shifts nicely. Firm. I figure if I tighten it up more it might be a bit harsh for lighter throttle driving.

    This car will be getting put away at the end of this month so its not that big of a deal. Just as long as I don't need any major work with the trans. I just want an idea of what's going on and if its bad or something to not be too concerned about.

    I'll most likely drop the pan sometime this winter while its in storage, is there anything to look for? Adjustments to be made? I know on my old 3 speed torqueflites you adjust the bands whenever you drop the pan.
    1987 Lincoln Town Car Signature Series-98k miles- LOPO 302, AOD, open 3.27, Dual exhaust w/ Thrush Turbo mufflers

    the others...
    1926 Dodge Brothers Business Sedan- 212ci I4/3 speed/crank start
    1987 Dodge Dakota- 3.9/A999/3.90/2wd (storage)
    1990 Jeep Grand Wagoneer-AMC360/727/NP229/3.08/2" lift(daily)
    1994 GMC Burban L05 350/4L60e/241/3.42
    2001 Jeep Cherokee 4.0/AW4/231/3.73 (limbo)

  5. #5
    Member ZackN920's Avatar
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    Hey Tiggie

    I don't have a tach in this car but when I've put it to the floor it sounds like it gets up there in the rpm's and shifts very firm into 2nd gear. It doesn't squak the tires but its a strong shift that ya really feel. Doesn't over rev or drop out, doesn't slip that I can tell.

    Huh, with how you have that written I figure this may be a common problem.

    Diagram would be great! What I should probably really do is find a service manual for the car.
    1987 Lincoln Town Car Signature Series-98k miles- LOPO 302, AOD, open 3.27, Dual exhaust w/ Thrush Turbo mufflers

    the others...
    1926 Dodge Brothers Business Sedan- 212ci I4/3 speed/crank start
    1987 Dodge Dakota- 3.9/A999/3.90/2wd (storage)
    1990 Jeep Grand Wagoneer-AMC360/727/NP229/3.08/2" lift(daily)
    1994 GMC Burban L05 350/4L60e/241/3.42
    2001 Jeep Cherokee 4.0/AW4/231/3.73 (limbo)

  6. #6
    Wagon Addicted Tiggie's Avatar
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    Here’s those valve body diagrams. Hope you can read them... if not let me know and I can get a better copy.












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