I have a completely stock 99 F-250 SD with over 320,000 miles. I walked outside about three weeks ago and saw where the trans leaked about 4qts of fluid all over the garage floor. I hadn't drove the truck in about two weeks but needed it then to get a load of hay. I topped the trans off with fluid, looked for the leak and it didn't leak. Drove it to get load and back home never leaked or gave me any problems. Now it's been sitting for about a week and it leaked another 4 or 5 qts of fluid again. I have checked the pan and found no sights of a leak. I know nothing about transmissions so can someone point me in the right direction to look. Thanks

 

My Fathers 02 was doing the samething around 360k miles i think it ended up being the rear main and somethin else ill have to ask him in the morning anyway his truck still ran an drove great to other then the leak

 

Drive it again... Then keep an eye on it... 4-5 quarts should give you plenty of time to see where it's coming from... Need to know where it's coming from...

 

More then likely its the pump seal at the front of the tranny behind the TC. Is it leaking near the front of the trans or rear?

 

Sounds to me like a torque converter drain back issue!

 

I know it's not coming from the rear main. From what I can see it looks like it coming from middle to front of trans. Hey Joel long time no see. How have you been doing? If the TC is leaking back down does that mean a new TC. I guess I need to slide the trans back and check the pump seal also. Is there anything on the side that could be leaking. When I first noticed it, it looked to be coming from the shift linkage area but the linkage looks to be bolted onto the side of the trans and doesn't actually go into the trans. Thanks for all the help guys!

 

I think if it was leaking from the side, it would be the other side, Pass side, from the cooler lines... If it was the front seal, it should be leaking out the hole in the inspection plate like mine does...

 

There is a plastic check valve in the pump that if it gets hot enough, it will melt/distort enough to allow fluid to slowly weep back into the transmission and overfill it to the point that the fluid level is way up inside the case causing it to have a static leak.
The way to correct it is remove the pump and replace the plastic check vale with a metal one from someone like sonnax, a job for someone with pretty good knowlege of transmissions.
Otherwise you could just start the truck and let it run for a a little bit every few days and it would probably stop leaking.