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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Leftys79 on April 27, 2011, 05:03:42 pm

Title: '79 C10 is leaking transmission fluid
Post by: Leftys79 on April 27, 2011, 05:03:42 pm
Just picked up a '79 C10 as a project truck. It is currently parked in my driveway (which is slightly uphill) and it is leaking transmission fluid. I got under the truck and it seems to coming mostly from the front portion of the transmission. I first noticed then when I went to put some new oil in, and the pan under the transmission was covered with fluid actively dripping off it and the joints around it.

I need to change the fluid in there and get a new filter in already, but want to get the leak taken care of before I drop more fluid in there.

Any insight into where this leak is coming from and what I can do to fix it?
Title: Re: '79 C10 is leaking transmission fluid
Post by: 78 Chevyrado on April 27, 2011, 05:49:20 pm
If it's coming out of the front of the trans ahead of the pan, it's most likely the front shaft seal.  It goes on like the seal at the driveshaft, but you have to pull the engine and trans apart to get to it.

Pull the inspection cover arouns the torque converter and see if there's fluid all over in there, if so, it's likely the front shaft seal.

If that's not it, Clean the whole trans rewally good and then go drive it just enough to make it leak, and dont drive fast so the wind will blow the fluid everywhere.  Then come home and chase down the leak, follow the fluid.
Title: Re: '79 C10 is leaking transmission fluid
Post by: Leftys79 on April 27, 2011, 07:03:31 pm
Thanks for the advice, I'll take the cover off tomorrow and have a look.

I'd love to drive it around and pinpoint the leak, but I think it has leaked too much fluid. It won't catch any gear when I try to shift now.  >:(
Title: Re: '79 C10 is leaking transmission fluid
Post by: beastie_3 on April 27, 2011, 11:58:33 pm
yup, not enough fluid.