First time poster, long time lurker, with a 4 wheel drive problem different than any I've seen. I'm taking a shot in the dark as a last resort. This has been the most reliable vehicle I've ever owned by a long shot, including my Honda cars and Toyota cars/trucks. Please help me because my 3 year old son absolutely loves this truck and would be devastated if I have to trade it in on a new Ecoboost F-150 lol. I have a lifted 99 Eddie Bauer 5.4 4x4 Expedition - see below:
I've owned it since 2006 @ 98k miles. I bought it, bone stock to the factory tire recommendation, from the original owner who used it for daily driver duty and to tow a fairly large offshore fishing boat about twice a week until the day I bought it. I had the transmission rebuilt by a highly respected Ford trans guy at 112k with upgraded parts and a handful of strength/durability improvements. The transmission has been rock solid. Currently the Expedition has 193k miles. This will be a little long winded so, if you're interested, please read along and offer some help if you can.
Some background on me:
I'm an above average home mechanic. I'm not a pro, or ASE certified, but I can handle 90% of repairs on my own. I have built engines, replaced engines, rebuilt differentials, installed suspension lifts, performed weld repairs, etc. One of the things I can't do? Rebuild transmissions/transfer cases. I can't figure out this problem and I don't want to throw away money without locating the actual problem. Before I remove the torsion bars and drop the T-case I wanted to get some ideas other than my own.
The situation:
Not long after I got the Expedition I had the dreaded banging/clunking in A4WD mode upon acceleration that plagues most of us. No issues in 4HI or 4LO. I performed the brown wire mod and all was great for about 2 years while I put the truck in 4WD on the beach, in the mud, etc. without a hiccup. While on a beach trip last year I was cruising along in 4HI when my friend got his Jeep stuck in front of me so I stopped. We dug out the Jeep and got it rolling again so I jumped back in the Expedition. When I tried to get going again (nothing crazy, just steady throttle) the the Expedition started to move and then a series of light "clicking" sounds, nothing violent (almost like a failing CV axle), happened and the back end buried itself. I put it in reverse, backed out of the hole fine, put it in drive, got it rolling again, and was doing fine for a few hundred yards in 4HI. As soon as we hit the deeper sand the clicking came back and the front tires wouldn't turn over - and I swear I smelled something burning, almost like a clutch or burning grease/gear oil. I locked it in 4LO and it came right out of the hole with no noise or problem. As we kept going I was still in 4LO chugging along when I decided to switch lanes (jump over ruts) so I turned the wheel and hit the gas a little (again, nothing crazy just light throttle). A loud, violent, clang..clang..clang is all I heard until I eased up on the throttle.
Where I'm at right now:
Truck works perfect while in A4WD (with brown wire mod).
Rear limited slip diff functioning perfectly.
All tires are exactly the same size and rotated regularly.
Brown wire mod.
Never had a problem with transfer case fill level (no leaking seal).
Transfer case fluid has been changed twice, no metal shavings, proper Mercon fluid.
No 4HI, when I hit the gas it clicks if there is any resistance, if I hammer the throttle from a dead stop I get "clicking" - no front wheel spin in any circumstance with 4HI.
4LO works fine until there is resistance and then "clang, clang", almost like a slipping chain, for as long as decent throttle is applied. Light throttle = no noise. I can also turn the wheels sharp to one side or the other and duplicate the "clanging" upon any throttle application, almost like it's binding up and unloading - front wheels still turn in both situations.
The entire front suspension, including CV axles and bearing assemblies, has been rebuilt (problem started before rebuild).
New hubs and there doesn't seem to be any obvious issues with the front diff or drive shaft.
Thoughts:
Could this be a problem with the front axle vacuum actuator? Doesn't seem likely to me since I can get 4WD, albeit noisy, in 4LO. Any way the shift motor, which is another common problem, could be causing this? At this point I'm contemplating a transfer case swap - or possibly an excuse for a truck swap - unless any of you have any ideas. For the record, I'd rather keep this one - it's awesome.
I've owned it since 2006 @ 98k miles. I bought it, bone stock to the factory tire recommendation, from the original owner who used it for daily driver duty and to tow a fairly large offshore fishing boat about twice a week until the day I bought it. I had the transmission rebuilt by a highly respected Ford trans guy at 112k with upgraded parts and a handful of strength/durability improvements. The transmission has been rock solid. Currently the Expedition has 193k miles. This will be a little long winded so, if you're interested, please read along and offer some help if you can.
Some background on me:
I'm an above average home mechanic. I'm not a pro, or ASE certified, but I can handle 90% of repairs on my own. I have built engines, replaced engines, rebuilt differentials, installed suspension lifts, performed weld repairs, etc. One of the things I can't do? Rebuild transmissions/transfer cases. I can't figure out this problem and I don't want to throw away money without locating the actual problem. Before I remove the torsion bars and drop the T-case I wanted to get some ideas other than my own.
The situation:
Not long after I got the Expedition I had the dreaded banging/clunking in A4WD mode upon acceleration that plagues most of us. No issues in 4HI or 4LO. I performed the brown wire mod and all was great for about 2 years while I put the truck in 4WD on the beach, in the mud, etc. without a hiccup. While on a beach trip last year I was cruising along in 4HI when my friend got his Jeep stuck in front of me so I stopped. We dug out the Jeep and got it rolling again so I jumped back in the Expedition. When I tried to get going again (nothing crazy, just steady throttle) the the Expedition started to move and then a series of light "clicking" sounds, nothing violent (almost like a failing CV axle), happened and the back end buried itself. I put it in reverse, backed out of the hole fine, put it in drive, got it rolling again, and was doing fine for a few hundred yards in 4HI. As soon as we hit the deeper sand the clicking came back and the front tires wouldn't turn over - and I swear I smelled something burning, almost like a clutch or burning grease/gear oil. I locked it in 4LO and it came right out of the hole with no noise or problem. As we kept going I was still in 4LO chugging along when I decided to switch lanes (jump over ruts) so I turned the wheel and hit the gas a little (again, nothing crazy just light throttle). A loud, violent, clang..clang..clang is all I heard until I eased up on the throttle.
Where I'm at right now:
Truck works perfect while in A4WD (with brown wire mod).
Rear limited slip diff functioning perfectly.
All tires are exactly the same size and rotated regularly.
Brown wire mod.
Never had a problem with transfer case fill level (no leaking seal).
Transfer case fluid has been changed twice, no metal shavings, proper Mercon fluid.
No 4HI, when I hit the gas it clicks if there is any resistance, if I hammer the throttle from a dead stop I get "clicking" - no front wheel spin in any circumstance with 4HI.
4LO works fine until there is resistance and then "clang, clang", almost like a slipping chain, for as long as decent throttle is applied. Light throttle = no noise. I can also turn the wheels sharp to one side or the other and duplicate the "clanging" upon any throttle application, almost like it's binding up and unloading - front wheels still turn in both situations.
The entire front suspension, including CV axles and bearing assemblies, has been rebuilt (problem started before rebuild).
New hubs and there doesn't seem to be any obvious issues with the front diff or drive shaft.
Thoughts:
Could this be a problem with the front axle vacuum actuator? Doesn't seem likely to me since I can get 4WD, albeit noisy, in 4LO. Any way the shift motor, which is another common problem, could be causing this? At this point I'm contemplating a transfer case swap - or possibly an excuse for a truck swap - unless any of you have any ideas. For the record, I'd rather keep this one - it's awesome.
