'08 GT 5-sp trans leak

Discussion in '2005+ Mustang GT 4.6L Tech' started by Lannyl81, Jun 10, 2021 at 6:24 PM.

  1. Lannyl81

    Lannyl81 Junior Member

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    Hello,
    New member....my daughter returned to our city after almost 5 yrs and so I once again get to work on her Mustang.
    Has just over 97k miles on it and has been problem free for the most part...but now it has a trans leak and I have not been able to determine from exactly where from.
    I think it is the tail housing output shaft seal. I cleaned the tail housing, then went for a short drive, got back under it and the tail housing again has an oily film coating. Just not sure if the oil is leaking down from the shifter area, the speed sensor, or is indeed the output shaft seal and the oil is just being blown/thrown forward when driving.

    Hopefully someone here has been through this and can tell me.

    Only thing I know to do would be to get the Mustang on 4 jack stands and run it, watch the trans to see if I can see the where the oil is coming from.

    Thanks in advance.
     
  2. Jason Dowdy

    Jason Dowdy Junior Member

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    I will almost bet it is the shift shaft seal. Just went through this myself. I changed the output seal and it kept leaking. Finally changed the shift shaft seal and it fixed it. You will need a good pick and patience to remove it. Use a socket to put it back on. And Ford couldn't get one anymore. Rockauto actually had one and I crossed the number and got it at Oreily's.
     
  3. golkhl

    golkhl forum member

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    When you change the seal, drain the trans and refill it with 3.2 quarts. I have tried a number of different gear oils in my 08 Bullitt over the last 13 years and 70k miles, currently running syncromesh.
     
  4. Lannyl81

    Lannyl81 Junior Member

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    Hey Jason, can the shift shaft seal be changed with the trans in the car?
     
  5. rocky61201

    rocky61201 forum member

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    Yes you can. I've never tried it but you might be able to do it with the shifter shaft in place. If you can't get it out and over the shifter shaft , then you can still remove the trans tailshaft cover (13 bolts IIRC). From there you can even service everything in the tailshaft, and shifter shaft seal itself.

    Just unbolt the driveshaft and remove the trans crossmember and let the transmission droop but still support it with a jack or block of wood or something.
     
  6. Lannyl81

    Lannyl81 Junior Member

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    Got it. Shifter seal ordered as well as the output seal. Going to be next week before they are both here. Fine with me....in the 110°F all week...not a good time to be in the garage.
     
  7. Lannyl81

    Lannyl81 Junior Member

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    I have looked through several TR-3650 service manuals and not a one of them show this shifter seal.
    Also do not see how the tail housing can come off unless the shifter box assembly is first removed...and that requires driving out a pin, removing a spring plate, etc. How in the world can this be done?
     
  8. rocky61201

    rocky61201 forum member

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    All of this can be done with the trans still in the car. I have done it when I broke the lock ring that retains 5th gear on the output shaft.

    You are correct none of them covers the shifter shaft seal but this one does cover the bearing that is in there as well. I don't know how that bearing could ever fail but there is a needle bearing in there and there is a seal trust me.

    Sorry I failed to mention the shifter assembly has to come out as well as disconnecting the driveshaft and removing the tailshaft flange as well which is probably the hardest part. Use an impact to remove the large nut and then a puller to get the flange off. Next step is removing the 12 or 13MM screw on the top of shifter linkage assembly. It is a pain to get at it up in the trans tunnel, but a short stuby wrench will do the trick. (See pic below) Be carefull when reinstalling this bolt as this part of the linage is soft aluminum and it can split if you over torque it.

    From there slide that part of the shifter linkage off the shaft, then remove the 12 bolts for the tailshaft cover. Remove the tailshaft cover and then you have full access to replace the shift shaft seal and also access to everything in the tailshaft. You can also inspect the magnet for shavings and change the fluid while you're at it.

    pic 1.jpg
     

    Attached Files:

    Last edited: Jun 13, 2021 at 2:38 PM
  9. rocky61201

    rocky61201 forum member

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    Here is every service manual I have on the TR3650. This is the 2006 and up version. Not the TR3650 used in previous generations of Mustangs.
     

    Attached Files:

  10. rocky61201

    rocky61201 forum member

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    Thought about it some more. The shift shaft seal if very small and sturdy and at the very top of the transmission and very little fluid makes it's way up there, but I suspect the main reason this shift shaft seal can go bad is old age, lots a miles, and excess vibration from other components that have gone the same route. Motor mounts, transmission mounts, shift linkage rubber and plastic bushings, driveshaft vibration, etc. etc. etc. You might want to spend some extra time and inspect everything related if you're planning on keep the car for a long time.

    If you want a really great and cheap upgrade for the shift linkage bushings get these.

    Amazon.com: AMP Tr3650 T5 Bronze Remote Shifter Bushing Kit: Automotive
     
    Last edited: Jun 13, 2021 at 2:40 PM
  11. Lannyl81

    Lannyl81 Junior Member

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    Thanks Rocky....I think all the TR3650 manuals I have viewed are for the older version...as the shifter area is quite different between the two.
    I have planned on removing the driveshaft and the output flange, draining the trans as well as I doubt the fluid has ever been changed.
    I previously looked at those bronze bushings....and would like to get them...but not knowing what daughter's plans are for the Mustang....would probably be throwing the $50 away.

    Thanks again....waiting for seals to arrive.
     
    2526Bullitt likes this.
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