I am in the process of rebuilding a totaled 1991 300 F-150 with only 39K miles and the E40D transmission. Thought it was a pretty good find! It was hit in the rear so I put a new box on it and it runs and drives GREAT. However, there is a slow leak from the tranny while idling/driving that is internal and exits at the rear of the extension housing of the tranny. I am assuming it is possible due to the driveshaft being tapped slightly during the hit. I replaced the output shaft seal at the rear of the extension housing and this did nothing to stop the leak.
After visiting with the guys at the local dealer, they suggested also replacing the copper bushing just ahead of the output shaft seal. They also said that the shaft runs in a small bath of fluid and that the bushing may have gotten smacked during the hit. Any ideas? From their diagram, it looks like the next part surroundng the shaft that is ahead of the bushing and involved with oil is much farther ahead and in the torque converter. This would undoubtedly be a more difficult fix and I would like to think it is just the bushing. I'm not sure where to begin next. Thanks in advance for the help!

 

>I am in the process of rebuilding a totaled 1991 300 F-150
>with only 39K miles and the E40D transmission. Thought it
>was a pretty good find! It was hit in the rear so I put a
>new box on it and it runs and drives GREAT. However, there
>is a slow leak from the tranny while idling/driving that is
>internal and exits at the rear of the extension housing of
>the tranny. I am assuming it is possible due to the
>driveshaft being tapped slightly during the hit. I replaced
>the output shaft seal at the rear of the extension housing
>and this did nothing to stop the leak.
>After visiting with the guys at the local dealer, they
>suggested also replacing the copper bushing just ahead of
>the output shaft seal. They also said that the shaft runs in
>a small bath of fluid and that the bushing may have gotten
>smacked during the hit. Any ideas? From their diagram, it
>looks like the next part surroundng the shaft that is ahead
>of the bushing and involved with oil is much farther ahead
>and in the torque converter. This would undoubtedly be a
>more difficult fix and I would like to think it is just the
>bushing. I'm not sure where to begin next. Thanks in
>advance for the help!


Sounds like one of two things here.
1.) your driveshaft yoke may have a burr on it and chewing up seal. Pull the shaft and check for burrs especially around the shaft sealing area on the yoke. The leak will appear to be coming from the inner perimeter of the seal at the shaft.

2.) your tailshaft may have a slight crack behind the outer perimeter of the shaft seal and is leaking there. If so locate the crack and then remove the tailshaft housing. Stick in dishwasher (make sure wife is visiting mother for a few days!) and then look for cracks (take both hands and try to twist, bend, fold and mutilate cover). once crack found drill a small hole in the end. Now mix up some J-B WELD, and slather on, over, in, and around crack. Warm up your oven to 200deg and put cover in oven for a couple hours. This will expand the metal slightly and allow the J-B weld to penetrate the pores better. Remove cover from oven and allow to sit overnight. Cut into slices and ........aw crap, wrong board! Install new seal, gaskets, and cover on E4OD. Install driveshaft and go for a drive.

Clean up dishwasher and oven REALLY GOOD BEFORE wife gets back from mother's!

Larry

 

Larry,
Thanks for the tips. I think maybe I should have been more clear about where exactly the oil was dropping from. The oil seems to follow the output shaft on the bottom side past the seal (exterior of rubber seal flange surrounding shaft does not come into contact with the shaft), continues the short distance to the yoke, and then drops shortly thereafter. Thus, I am led to believe that the leak is internal and not output case related. It seems to me that the exterior portion of the ouput shaft seal is more of a dust/mud seal than anything else and the inner portion that butts against the bushing is what does most of the work...in fact, the part of the seal closest to the yoke has a small drain hole at the 6:00 position. Anyone else think it's the seal and/or bushing combination or could it be something totally different? Thanks again to everyone for the help!
Brian

 

>Larry,
>Thanks for the tips. I think maybe I should have been more
>clear about where exactly the oil was dropping from. The oil
>seems to follow the output shaft on the bottom side past the
>seal (exterior of rubber seal flange surrounding shaft does
>not come into contact with the shaft), continues the short
>distance to the yoke, and then drops shortly thereafter.
>Thus, I am led to believe that the leak is internal and not
>output case related. It seems to me that the exterior
>portion of the ouput shaft seal is more of a dust/mud seal
>than anything else and the inner portion that butts against
>the bushing is what does most of the work...in fact, the
>part of the seal closest to the yoke has a small drain hole
>at the 6:00 position. Anyone else think it's the seal and/or
>bushing combination or could it be something totally
>different? Thanks again to everyone for the help!
>Brian


The seal should have a minimal contact with the shaft. It's a combination mud/dirt/dust/fluid seal. Just like the Front main on your engine. It's not supposed to leak. The other thing to do is check your fluid level on a level area with the engine / trans hot. in park and running. I keep mine an 1/8" below the full mark all the time. Don't fill to top as an overfill condition will allow fluid to leak from rear at the output shaft.

Look for a slight undercut area on the yoke. if it's undercut/worn then you need to replace the yoke. You really shouldn't be getting a leak along the bottom of the shaft unless one of the above is happening.