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Gmc 2500 Problem Need Help!

Discussion in 'Chevy Trucks' started by CGLC, Oct 8, 2006.

  1. CGLC

    CGLC Senior Member
    Messages: 100

    I have a 1998 2500 (49000 miles) GMC and just recently noticed that when I pull it out of the garage there is a tranny fluid stain on the ground( the stain is dripping under the tranny pan). It is not a lot of fluid, and it does not occur every day. I notice the spot maybe once or twice every two weeks, but the stain is increasing in size over the past couple of months. The dishearten part is today; next to the stain, I notice another spot that looked like engine coolant (very small in size maybe three quarters but back by the tranny). About a month ago I had the dealership change the fluid and replace the filter. Any help on this would be really appreciated, I don’t have a lot of time to check this thread so don’t take offense if I do not respond right away. Thanks plow site members!
     
  2. lawnmedic

    lawnmedic Senior Member
    Messages: 703

    Need to get under the truck and figure out where the leak is at. It could be a loose pan, but I would start looking around the input shaft seal. Pull the torque converter cover off and see if the back of the converter is wet....
     
  3. CGLC

    CGLC Senior Member
    Messages: 100

    :confused: Ya i looked under the truck and the pan was covered with a thin tranny film. I tried tightening the bold and they seemed tight. :confused:
    if the back of the converter is wet what would i do then and is this a serious problem i have that requires immediate service.
     
    Last edited: Oct 8, 2006
  4. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    If the back of the convertor is wet, the input seal on the transmission pump is deteriorating. In order to replace it, you'd need to pull the tranny right out, no small task, especially if the truck is 4wd.

    If the problem is really small like you describe and not increasing quickly, I'd be tempted to leave it and just check the fluid level occasionally.... but of course the chance you take is eventual seal failure... which seems unlikely.

    Another thing you can do to make diagnosing a little easier is get an aerosol can of Brake Cleaner and spray and wipe down the pan, so you can see better. Remember that overtightening pan bolts can a)split the gasket, or b)warp the pan, both of which can cause minor leaks as well. It it also of note that RTV silicone doesn't like ATF.

    As for the coolant, if its at the back with the tranny leak, it could possibly be from the heater core area (think hoses etc.) or if its dripping off the engine, possibly intake gaskets going bad. You'll need to investigate some more.
     
  5. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I had an input shaft seal go on my '93 1500. I don't think my shop pulled the tranny tho, atleast not for the $143 that they charged me. So, you might want to start there. I am not sure if that is the input Derek is talking about.
     
  6. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Are you sure that wasn't the output shaft seal or something? The input shaft seal is behind the torque convertor, on a shaft... which cannot be accessed without dropping the tranny.
     
  7. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    That's it. It was the output shaft. I knew it was one of the two lol! Disregard what I previously said.
     
  8. CGLC

    CGLC Senior Member
    Messages: 100

    Thank you very much for your help.
     
  9. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Was that the problem?