Help 89 5.0 Leaking Manual Transmission Fluid.

Discussion in 'Fox 5.0 Mustang' started by Slo5Oh89, Nov 2, 2009.

  1. Slo5Oh89 Member

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    My tranny started leaking fluid from seems to be the rear. Any help please? Is this a gasket or RVT becuase i was able to pull peices off of what seemed to be RVT? I recently had new clutch installed.
  2. Mustang5L5 Founding Member

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    If it's the rear where the driveshaft slides in, then there is a seal you can replace.

    If it's between the tailhousing and main case, then you need to remove the tailhousing as it's RTV.

    EVery time i've replace a T-5 or reinstalled one, it's leaked a short time from the tailhousing seal. Usually disappears after a while and i just top the fluid off. However, since the trans was just out, the seal could have been damaged.

    Of course, that's if that's where the leak comes from
  3. Slo5Oh89 Member

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    Thank you so much. I think it is where the RVT is I was able to peal some off that was haning down. Easy fix?
  4. Prime Lord Crappy Default Title

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    So you think its leaking from where the body of the transmission mates to the tailshaft? If thats the case, you'll have to pull the driveshaft and unbolt the tailshaft. Re-RTV and bolt it back on.

    I would double check it though before you go through the headache of taking the tranny apart. The slip yoke seal is the most common leak point for the T5. The seal costs like $5 and all you have to do is pull the driveshaft and use a seal puller to pop the old one out and a rubber mallet (and big-ass socket) and lightly tap the new one back in.
  5. spoulson New Member

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    What RTV is commonly used for sealing the case?

    In previous projects (non-Mustang), I've used Dodge axle sealant or Permatex anaerobic sealant.
  6. Prime Lord Crappy Default Title

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    I don't see why one of the high temp Permatex RTV's wouldn't work. I usually use Permatex Ultra Copper for everything unless its a specific application where that would be a bad idea.
  7. spoulson New Member

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    Supposedly, standard RTV is not rated for gear oil. I guess that depends on what you run in your trans and what you believe. Haven't had issues with what I used after 40k miles on rebuild of a Mitsu AWD trans. Factory service manual called for this type of RTV.
  8. Prime Lord Crappy Default Title

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    Well the T5 uses ATF which is much less corrosive than say 90w gear oil (like that used in the rear end). And if I remember correctly, Permatex makes an RTV that is specifically made to resist gear oil.
  9. Mustang5L5 Founding Member

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    Make sure it's not the speedo cable leaking down as well. Another common problem.

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