I have a 1990 F150 with a 302 mated to an E4OD, which has been leaking non stop at a rate of probably a drip every 1 minute

I have never been able to track down the location of the leak because, in looking at the tranny pan, there are probably 5-7 fluid drip points. Obviously there are not any holes in the pan itself, so for a while i started to think that the pan gasket was bad. I should also mention that each one of the screw heads for the pan are covered in fluid, and the entire under side of the truck around the transmission has fluid just from the wind blowing it around while driving.

WELL! I was just finishing up an oil change and decided to check the tranny fluid level. I thought that it would be really low, since it had been leaking since i got the truck about a month ago. I was wrong! it was way over filled.. by ATLEAST a whole quart, if not 1 1/2 quarts..

So now, this being the case, im starting to think that this is the real reason my transmission is leaking so bad. So my questions are as follows:

1. Can overfilling cause high pressure?
2. Are there any vents on the tranny itself that can leak fluid if it is filled past a certain point??

PS: The previous owner filled the tranny last, he was not a good mechanic, so ive come to find.

 

Did you have the engine running when you checked the fluid level?

 

no, the engine was already off for about 10 minutes but was at operating temp, or just below

 

That doesn't work for checking the fluid level. When the engine is running some of the fluid is in the torque converter and maybe other places. The engine must be running and yes preferably with the transmission at operating temperature to get a correct reading. With the transmission below operating temperature the level would read a bit lower.

 

A gasket is not going to leak at that rate unless something is loose. If it is overfilled, fluid will come out the top from the vent. Best way to check fluid is to completely warm,you have to drive it, idling it this time of year will take forever, run the gear shift momentarily in each position stopping in park and check the level. Next best you can do it cold to make sure you are in the ball park. Repeat the same procedure cold, the level should be about halfway within the "add" section, no higher. Either way, you have to run through each gear selection and check level in park.

 

Of course fluid is everywhere due to driving - WASH IT before attempting to find a leak. It might be coming from the PS system, which is known to leak profusely, and uses the same ATF. Start at the BOTTOM (so soap & water aren't dripping on your face), and work your way up, then back down to finish. Let it air-dry so you don't pump fluid out, but you CAN use a leaf blower.

(phone app link)


Once it's dry, let it idle JUST FOR A MINUTE to try to start the leak. Then shut it off & start looking for the FIRST trickle, and follow it forward & up to the actual source. If there's nothing, run it a little longer while you continue checking with a flashlight & inspection mirror. You can also use your phone camera, or (with newer Android phones) an inexpensive USB borescope like this:
Try to find one that a reviewer says actually works with your model of phone.

 

and control the amount of fluid drained.[/QUOTE]

well.. this is pretty embarrassing. Today I got under the truck to check the torque on the pan bolts only to find that they were all BARELY finger tightened.. a few of them spinning freely. This is without a doubt the reason for the heavy leakage. I just assumed that they were tightened to spec.. it’s so hard to believe someone took the pan off and forgot to re-torque the bolts when re installing. Oh well!! Problem solved! Thanks

 

That's not what happened. The gasket compressed & hardened over the years, reducing the torque on the bolts. It'll start leaking again, eventually. When it does, be prepared with a new 1-piece modern-rubber gasket (I prefer Mahle since it was Ford's OEM in '96) and the equipment & knowledge to pull the engine out & re-seal it. Read this caption & the NEXT several:

(phone app link)

 

Thanks for the link its a great reference. I really want to pull the engine to clean it up and reseal everything exactly the way you did, i just need the space to do it since i live in an apartment. The whole process seems somewhat simple. My F150 is a California truck and i have not had any issues disassembling things as of yet.