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    Transmission Noises and Leaks

    I'm experiencing a number of transmission related issues now that the engine's sorted and the car's sat for seven months. Up until now the AOD has run fairly well. There were a couple isolated cases of the car bucking at cruising speed on the way down from Washington, and once before then when the transmission didn't respond to my shift from drive to reverse on the first try. But otherwise it's done its job. The TV cable bushing was missing when I bought the car, but the cable seemed to be wedged in there precariously and I immediately had the brass bushing put on.

    Running the engine tonight and earlier in the week produced a loud sound from near the transmission, somewhere between a buzz and a duck. The first time it was continuous from the point it started, but tonight it began maybe 15 seconds after starting the car and then went away after 30 seconds. I ran through the gears right after starting the car and everything sounded pretty good, but a couple minutes later when I threw it into reverse there was a loud clunk followed by a screech as I shifted back into park.

    There were small leaks that pooled below the transmission. One appears to have come from around the output shaft seal and the other probably came from the pan gasket, but I'm not sure if it could've started above the pan and trickled down. The leaks were definitely transmission fluid, though. There was a third leak at one of the quick disconnects going into the oil cooler, but I took care of that.

    I suspect the fluid is low and hopefully topping it off will resolve some of these noises. The dipstick picture is from 20-30 minutes after running for 4-5 minutes, so more or less cold. I don't understand the difference between the holes and crosshatch on the dipstick, or whether a cold measurement means anything, so I've held off on adding fluid willy nilly. I also don't want to add too much fluid accidentally. I currently have three gallons of Dexron III/Mercon and a replacement filter kit if that seems like the way to go. If so, is this also the time to replace the output shaft seal? Or is this AOD on its way out?

    Here's a video that shows some of the noises: https://www.youtube.com/watch?v=ONP-vwO4Nb4
    Attached Files
    1987 Lincoln Town Car - Signature, "Prudence"

    #2
    As I understand it, the lower set of holes are for checking it cold. Should be between the two lower holes.

    You are checking it running, in park, right?

    Fluid color looks decent.

    The buzzing sound is an AOD thing. Some just do it. I had one once that did it a lot but was the best AOD otherwise. I don’t think it’s something to worry about.

    Get the fluid level right, drive it, Hope for the best, and address leaks if it behaves. If something is still grinding inside, there’s not much you can do but pull the trans.
    1990 Country Squire - weekend cruiser, next project
    1988 Crown Vic LTD Wagon - waiting in the wings

    GMN Box Panther History
    Box Panther Horsepower and Torque Ratings
    Box Panther Production Numbers

    Comment


      #3
      I don't know what the buzz is, but its a "thing". Probably some mix of a slightly sloppy part and slightly high TV pressure making it rattle. My best-shifting AOD also does it.

      not sure what the noise going from reverse to park might be but that doesn't sound like a happy noise. Unless it was bad U joints and the noise was not actually internal to the trans. Still not a happy noise.


      fluid might be slightly low, let it warm up fully and see what you get. Fluid looks OK condition-wise tho. If its not smelly and all the gears work I'd run it till it does something screwed up.

      Above the pan gasket could be from the neutral/reverse switch or from a leaky shaft seal on the shift selector. There is an inner and outer one on that since the TV linkage runs through the middle. Rear is usually rear seal, but if the yoke from the driveshaft has been damaged it will eat the seal. Same if the tailshaft bushing is badly worn. Worth a feel to make sure the surfaces are smooth and the driveshaft doesn't flop around too much when you change the rear seal.
      86 Lincoln Town Car (Galactica).
      5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

      91 Lincoln Mark VII LSC grandpa spec white and cranberry

      1984 Lincoln Continental TurboDiesel - rolls coal

      Originally posted by phayzer5
      I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

      Comment


        #4
        In the video the speedometer was showing 5 MPH when you put it in park, that would make any transmission grind to a stop.

        Comment


          #5
          Yeah, I noticed the speedometer when I was looking at the video. Could've sworn I had my foot on the brakes. So that explains the Reverse to Park noise.

          The buzz has been happening less each time I start the car, but if it's benign then I guess there's no point paying attention to it.

          I added three pints (!) of fluid and after running it through all the gears it looks to be right around the bottom of the crosshatch. The owners manual says to drive it 20 miles before checking, but I'm loathe to drive it too far until I get it smog tested and registered. So hopefully it drives well tonight and going forward. Should I manage to get it legal again I'm leaning toward taking it to a shop for a flush/filter change and maybe the rear seal.
          1987 Lincoln Town Car - Signature, "Prudence"

          Comment


            #6
            Well here we are a year later and I still haven't addressed the transmission. But the time is definitely approaching.

            There's a pretty significant leak coming out of the rear. Presumably from the output shaft seal, but it drips from the front u-joint. One drip maybe every thirty seconds. I've had the car on jack stands for about a month now and it's still going. The picture below is what's come out in the past two weeks. The fluid, at least, is still red, but I assume it's dark enough that it needs changing.

            Since replacing the transmission mount and u-joints I can't feel any slop between the trans and driveshaft. Is this a good sign that the bushing behind the seal is okay, or do I have to feel it to know?

            I would have already tackled the seal, but the shop that serviced my differential and u-joints really tightened the driveshaft bolts good. Will have to go into the auto craft shop to use a bigger wrench or an air tool.

            1987 Lincoln Town Car - Signature, "Prudence"

            Comment


              #7
              12mm 12 point wrench and a hammer. Can also double wrench the 12mm12 point:

              ~David~

              My 1987 Crown Victoria Coupe: The Brown Blob
              My 2004 Mercedes Benz E320:The Benz

              Originally posted by ootdega
              My life is a long series of "nevermind" and "I guess not."

              Originally posted by DerekTheGreat
              But, that's just coming from me, this site's biggest pessimist. Best of luck

              Originally posted by gadget73
              my car starts and it has AC. Yours doesn't start and it has no AC. Seems obvious to me.




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                #8
                yeah they're a bit of a bitch to do

                If you're pulling the drive shaft it won't take much to inspect the bushing anyway. There is a special tool to change it though, so unless you have it or are removing the tailshaft it doesn't much matter if its actually bad. There is an O ring on the output shaft of the trans which also is supposed to keep fluid from getting down inside the yoke. If you pull the driveshaft and the splines are full of fluid, you're probably going to need to change that.

                Seems strange to me that the fluid level is high enough to continue to run out the tail end of the trans like that. You can normally pull a driveshaft and nothing comes out, meaning the fluid is below that point. If yours is over-full by a fair bit it will puke fluid.
                86 Lincoln Town Car (Galactica).
                5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                91 Lincoln Mark VII LSC grandpa spec white and cranberry

                1984 Lincoln Continental TurboDiesel - rolls coal

                Originally posted by phayzer5
                I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                Comment


                  #9
                  Thanks, David, I'll give that a try.

                  The car isn't level at the moment. The front wheels are off the ground while the rears are just barely touching, so I assume it has more to do with fluid running to the back than the level being too high.

                  If the O ring is bad, how do I go about finding a replacement? Is it a special material? I'm sure a rebuild kit would have it, but if I can just buy one part instead of several dozen I don't need, that would be preferable.
                  1987 Lincoln Town Car - Signature, "Prudence"

                  Comment


                    #10
                    its just an O ring, should be able to pull it off and match it somewhere. Standard black nitrile ought to be OK for trans fluid. Green AC O-rings would also work fine.

                    tilt would explain the ongoing leak.
                    86 Lincoln Town Car (Galactica).
                    5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                    91 Lincoln Mark VII LSC grandpa spec white and cranberry

                    1984 Lincoln Continental TurboDiesel - rolls coal

                    Originally posted by phayzer5
                    I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                    Comment


                      #11
                      Several of mine buzz along similar lines of annoyance as a cicada in a nearby tree. Sort of like your buzz, but it ramps up and does not waver once it reaches its full intensity, before it eventually trails off and is gone until its next appearance. It seems to just be what they do. After driving, if I shift into park, it will buzz for a minute or so, then stop. I can shut it up immediately by moving the lever to any other position, then when I put it in park again, it may or may not begin buzzing again. On the cars where I have TV set on the high side (to shift in a manner I consider more desirable), two other conditions can get the buzz as well: using manual 1, or accelerating in D/OD gradually enough over a long distance that I'm in second gear for a long time.

                      All of the cars I've put any sort of mileage on have had their trans fluid changed with a store brand (Shell-manufactured) DexIII/Mercon equivalent. It is not marketed as synthetic. Not sure if the fluid maybe plays a role.

                      I would guess, and I think this comes from past input of others, that the buzzing is a vibrating check ball in the valve body being rapidfire seated-unseated due to something about how the fluid is being routed in those moments.

                      A sound that I get which others seem to not talk about is a very high pitch squeal noise (think noisy CRT TV) at the top end of gears right before a shift. I've now had enough of my cars do it for long enough that I'm convinced it is also just a normal thing. I am very sensitive to noises that many people around me seem totally unable to hear, so I'm sure that's part of it.
                      Last edited by kishy; 10-10-2021, 11:42 AM.

                      Current driver: Ranger
                      Panthers: 83 GM 2dr | 84 TC | 85 CS
                      | 88 TC | 91 GM
                      Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
                      Gone: 97 CV | 83 TC | 04 Focus | 86 GM
                      | Junkyards

                      Comment


                        #12
                        AOD's have fairly straight-cut gears, a whine in 1 and 2 especially is common. The AODE and 4R70w do it too.
                        86 Lincoln Town Car (Galactica).
                        5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                        91 Lincoln Mark VII LSC grandpa spec white and cranberry

                        1984 Lincoln Continental TurboDiesel - rolls coal

                        Originally posted by phayzer5
                        I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                        Comment


                          #13
                          Originally posted by gadget73 View Post
                          AOD's have fairly straight-cut gears, a whine in 1 and 2 especially is common. The AODE and 4R70w do it too.
                          Assuming that is with respect to my remarks and not an in-general: Not that sound. I know that sound. This is a hydraulic sound...maybe a high pressure leak past a valve or something.

                          I've come to accept it as just being normal, or at least normal with age. Anyone older than me can't seem to hear it at all.

                          Current driver: Ranger
                          Panthers: 83 GM 2dr | 84 TC | 85 CS
                          | 88 TC | 91 GM
                          Not Panthers: 85 Ranger | Ranger trailer | 91 Acclaim | 05 Focus
                          Gone: 97 CV | 83 TC | 04 Focus | 86 GM
                          | Junkyards

                          Comment


                            #14
                            According to the Baughman shift kits I have used- the buzzing sound can be fixed by replacing the TV spring with an updated (possibly stiffer, it was hard to tell) spring that comes with the kit. I'm not sure if you can buy the spring separately, but if it really bothers you, you could replace it, or do a mild shift kit since you're already in there...

                            If you take the tailshaft housing off it's not too hard to replace the bushing. I use a sawzall blade to carefully cut through the old one, at which point it'll basically fall out, and use a piece of wood and hammer to gently hammer the new one in.

                            Driveshaft bolts-sometimes they use locktite and heating them a bit first helps break the bond
                            -Phil

                            sigpic

                            +1982 Ford LTD-S Police Car. Built 351w, Trickflow 11R 190 Heads, Holley Sniper EFI, RPM Intake+ Hyperspark dizzy, WR-AOD, Full exhaust headers to tails. 3.27 Trac-Lok Rear. Aluminum Police Driveshaft. Speedway Springs+Bilstein Shocks, Intermediate Brakes, HPP Steering Box.

                            +2003 Acura CL Type S 6-speed

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                              #15
                              Well I pulled the driveshaft today. The double wrench trick worked like a charm. I frequently find myself just not giving things enough muscle, or worrying too much about breaking things. Maybe that's from growing up working on computers. Anyway, this has been a great opportunity to clean the driveshaft and tunnel of all the caked on oil that I assume was deposited from the intake manifold when its gaskets failed. Not very fun removing sludge that's above you, but the results are satisfying.

                              Now that it's off, I've found a couple things:

                              One, the output shaft splines are full of fluid, which I understand means an o-ring has gone bad. I don't see any o-ring, though. Does it require removing the tailshaft housing to replace?

                              Two, the bushing and driveshaft look to be okay. I didn't notice any marring on the driveshaft, so I'm probably going to leave the bushing be.

                              Three, fluid seems to have passed through the middle of the driveshaft to drip from the u-joint. It looks like there's some sort of black seal in there. Is this something that needs to be serviced or will the output shaft o-ring keep fluid from getting there?

                              Four, the output shaft seal Amazon told me would fit (7692S) doesn't. It looks to be almost 2 1/2" diameter, while the old seal is closer to 2 3/8". Does anyone have a part number for a seal that will fit?
                              1987 Lincoln Town Car - Signature, "Prudence"

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