2000 F350 7.3 four wheel drive, 80,000 miles. The last transmission service was 20,000 miles ago. Today after about a 100 mile run on the freeway at 80 mph empty I noticed oil spray on the tailgate. It's leaking ATF down the rear left (driver's) side of the transmission case, dripping from the transmission mount crossmember, and appears to be coming from on top of or high up on the transmission. Leak is what I would call a moderate amount of oil. I did not notice anything unusual about the shifting during the drive. Any ideas?

 

I believe the vent is on the top of the tranny. If it was over-filled, the "high-speed" drive could have caused the excess fluid to be pushed out the vent. If the fluid level wasn't the problem, a blockage could cause enough pressure to make the fluid 'vent' too.

 

I second the above. Check the vent tube first, and determine proper fluid level before getting too concerned something major is wrong.

 

That was my initial reaction, but I am having hard time convincing myself. The last time any fluid was added was at the service 20,000 miles ago, and it has been driven at the same speeds for a much longer distance and in hotter weather since the last time ATF was added. I looked at it with a mirror last night and now suspect that the ATF is either coming from between the adapter for the t-case and the transmission, or from the left rear corner of the transmission pan and in that case is being blown up on the side of the transmission. What has me stumped is how this big of a leak at either of those locations could develop so spontaneously. Today the leak seems to have slowed but not stopped. I havn't looked at it with the engine running, I'll do that next. Nobody else with similar expierence? It's just my luck to be the first.

 

I am having the same leak, or so it sounds like the same. I replaced the gasket between the trans and the extension housing as well as the one between the extension housing and transfer case but still have the leak. Did you ever figure out what the cause was? I’m still not sure

 

He hasn't posted here in more than six years, so don't expect a reply from him.

With the transmission warmed up, engine idling, and in park, what is the ATF level?

 

I have only been putting about a gallon in, after it was completely drained and I replaced those gasket I mentioned in the last comment, because I didn’t want to put all the trans fluid in that it takes just have it all go to waste and need to be drained back out or even just leak out. I put a gallon in to test if it still leaks and it does so I didn’t add anymore after that.
I also can’t get the trans up to temp because even at full the leak is so bad that it will all have leaked out long before it warms up.

 

Did you drain the pan and torque converter, too?

 

I pulled the drain plug on the pan, don’t know how to drain the torque converter, and why would that affect the leak?

 

It wouldn't affect the leak, it would affect how much fluid is in the transmission.

I think you need to check the trans fluid level even if you can't get it warmed up. Either you have a serious hole in the trans or it's overfilled.

 

did you fix this? I'm about to drop mine in a 02 7.3 4x4 also. I thought is was hair line cracks. Which it was. I think my drive shaft was out of balance. I thought I had it fixed. Then I was downtown in San Diego. Started slipping in a hill them lost all drive. Dumped fluid everywhere
I parked it and stopped until I could get money for a rebuilt trans. I'm thinking of rebuilding myself