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Pete, Automotive Mechanic
Category: Transmissions
Satisfied Customers: 28250
Experience:  GM and Mercedes vehicle technician.17 years experience.
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Ford E-350 Econoline: and thanks in advance help.

Customer Question

Hello and thanks in advance for any help. I have a 1995 Ford E-350 XL (~190K miles) with the 5.8L and E4OD with a rotational "thunking" or "clunking" that I believe is a transmission problem. Van has no history of problems, shifts fine (still).
HISTORY of issue:
A few months back I replaced the radiator, which involved some AT fluid loss and I refilled it by checking the stick (engine running, cycled through gears, checked in park), then drove it a bit and rechecked it. I don't think this caused the problem but I'll include it just in case.
Last month this van was used for a long journey (Seattle to Boise and back). Prior to the trip I checked all fluids (including transmission), and greased the front and rear U-joints.
On the return from Boise I started to notice a very quiet whir/vibration from underneath the front two seats. It started around 10mph and was constant above that. I checked the U-joints but they didn't seem to have any play. Check fluids again, and underneath for leaks and noticed nothing except that where the drive shaft connects to the output shaft/slip yolk into the transmission there was a very slight amount of movement. Maybe 1mm or less. I don't know if this is normal. The rest of the trip was fine with no changes. I checked brake calipers, steering and such just to see if anything else was loose and couldn't find anything obvious.
It sat for two weeks. Then I did a short drive around town. The noise and vibration got significantly worse. It starts more or less immediately with any forward or reverse movement so I did more involved troubleshooting. It sounds like a heavy, rhythmic "thunk-thunk-thunk" with a linear relationship to speed.
-Occurs both forward and reverse
-Starts immediately with movement (at a slow walking pace the thunk spacing is maybe 3 seconds)
-gets worse with speed, shakes entire van now (van is currently parked as by 10 mph it is bad enough I don't want to drive it and make something worse)
-Seems to stop while moving when put in Neutral, starts immediately back in a Drive gear
-No unusual engine RPM required for movement
-Occurs during Acceleration, Constant Speed, Coasting, and Braking.
Troubleshooting I've done
-Pulled off drive-shaft and:
-Checked U-joints for obviously play
-Checked Rear Differential input for play
-Checked slip-yoke for binding/free in-out movement
-Checked output shaft for play (still same slight play as before)
-I disconnected the drive-shaft from the rear diff. and:
-handed turned the shaft/transmission in R-N-D-2-1 but felt no binding/bumps
-with shaft suspended connected to transmission but not rear diff. and engine running put the transmission into R-N-D-2-1 and did not hear or feel much of anything except maybe a quiet click I couldn't locate (though maybe a load is required to manifest the issue).
Submitted: 2 years ago.
Category: Transmissions
Expert:  Pete replied 2 years ago.
My name is ***** ***** I am a professional here at Just Answer. I noticed that your question was not getting a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.
From what you have described here since this is heard or felt through the front two seats the best and you have normal play in the drive line and all U joints are good this sounds like a bearing is starting to fail in the transmission itself causing this issue here.I have seen bearing failure cause this type of fault here before in the past and had to remove the transmission and take it apart for an inspection and repair.
Most likely the transmission will need removed and taken apart for inspection and then repaired from there.
Thanks Pete