I have a 1991 F150 with a v8 and an auto transmission. The problem is when the vehicle is driven for more than 5-10 minutes(enough for the temp gauge to start moving) the transmission fluid will begin leaking from the bottom front of the tranny near the black rubber cover. Maybe just a coincidence but I really did not notice the problem until after I had the transmission flushed(hook up machine and flush tranny fluid through transmission while vechicle is running) at a local auto shop. I have checked the fluid and the level is still within the normal range according to the dipstick. As much fluid that has leaked, it appears that the tranny was overfilled during the service. Well the leaking continues and the level is slowly dropping. It has been at least six months since I had the service done, I don't drive the truck much so I don't see the problem too often. I guess I should start by taking it back to the shop and having them make sure what they did is not causing this problem. Any other suggestions would be greatly appreciated. I am trying to sell this truck and would like to know what a possible buyer may be facing here.

 

Well I'm not sure if this could be it or not but my brother chased a transmission leak for months after having his 91 auto rebuilt. After taking the pan off and on about 4 times they figured out it was the o-ring on the dipstick tube. It leaked like a sieve.

Hope that helps

 

Thanks for the response, I checked out the dipstick today and it is definitely not leaking. I removed the dust cap from the bottom of the transmission and drove the truck a while and when I went to check, it appeared that tranny fluid was leaking from inside where the dust cap goes.

 

Wish I could be more help on that one but I think you are out of my range at this point. I never worked on the auto's a whole lot. I'm sure someone will chime in and maybe give you another lead.

 

If it has a drainplug on the torque converter, check it. If that's fine, the most common transmission leak from that area is the front seal. It's a transmission removal for a $5 part to fix it, so try some transmission leak additive first.

 

Sounds like a leaky front seal to me.
Alan