99 & up 7.3L Power Stroke Engine and DrivetrainDiscussion of the 99 & up 7.3L Power Stroke diesel engine and drivetrain in the 1999-Up Super Duty trucks and Excursions. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 7.3L Power Stroke engine.
Hello, new to this forum and the diesel world. This is my first diesel so Im learning as I go. I did a quick search for my problem but only finding info if the light on the dash does not come on.
2002 F350 SRW 4x4 LB 152xxx miles
Here is the problem, Last week I replaced the upper and lower ball joints, both u joints, new vacuum seals, new outer dust caps. Also pulled the front diff apart and noticed the bearings where dull so put new bearings in. This was not a easy job but it was fun and I learned alot. Even bent a press i bought for doing the ball joints ( from Harbor Freight , had China stamped on it). Anyways got everything back together. Pulled out of the shop, checked the 4 wheel drive many times and things seemed good. Drove 2500 miles in 4 days, truck still running fine. Few more days pass and I I start to feel a small vibration in the front. Unlocked the hubs and it went away. It snowed and I had to pull my enclosed trailer so I looked the hubs back in. Got on the highway and felt a good vibration going on at 55-65 mph. 4 wheel drive not engaged. Got stuck on a icy hill and tried to put it in 4 but it would not engage. Had to get a tow from a Toyota Tundra..... Drove home and still had vibration, unlocked hubs and still there but not as bad. Dropped the trail and tried to check the 4 wheel drive on a snowy road and nothing.
My question is could this be the vacuum line? Or a bearing in the diff?
Reason I ask about the diff is I did not have a press so I went old school and cut them off, stuck the diff outside for a little (cold), heated up the bearing with a torch and dropped them on. One spot on the bearing did change color and lost the shinny on each bearing. Yes I know this was not the right way but I was pressed for time and took a chance and now I think I might be paying for it.
I'm only able to contribute a little here, but the question I have is are your hubs in the auto position, or are they in the lock position? If it's a vacuum problem and your hubs are in auto, then that could cause the hubs to not lock. But if your hubs are in the lock position (or does it say manual? I forget) and you turn the knob inside the cab to 4WD and the 4WD doesn't engage, then it may not be a vacuum problem because when the hubs are in the lock position and you turn the 4WD knob the vacuum system is not involved in making it go into 4WD. Also, I had a vibration problem around 30-40 mpy or so and it turned out that one of my auto locking hubs was torn up inside and causing the vibration. I ended up just replacing both hubs with Warn manuals. Now I KNOW they are going to work when I turn the 4WD drive knob.
It's not a bearing in the differential. If that were the case, you'd hear crunching sounds if the axles weren't turning with the driveshaft.
Most likely locking hub vacuum issues, which you can check by putting the truck in 4x4 and jacking up one front wheel and trying to turn it. If it turns freely, the locking hubs aren't locking up.
Could also be the t-case motor. Again check that by jacking up one wheel and attempting to turn the front driveshaft when in 4x4. If it (and the jacked up wheel) turns, then the t-case isn't engaging.
The vibration in 4x4 could be a bad driveshaft u-joint. Did you index the driveshaft yokes before you pulled them off, and did you put them back on in the same position?
The transfer case is electric so check your fuses and you should hear the motor engage the tc. If you are locking your hubs manually a vacuum leak is irrelevant, it would only cause an issue if your using them on auto.
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2002 F-350 CC Longbed
DIY Tymar intake
4" Turbo back with no cat/muffler
Full set of gauges
Superchip Flashpack
6.5" Lift with 37 x12.50 BFG
Thanks for the info.... give me a place to start. One thing that I noticed was when I tured the hubs to the Auto position?? The problem started. I have always driven around with the hubs in lock position. Im not use to this auto 4 wheele drive. I figured forward to have 4 wheele drive and back to not engage it. Also Im sure the hubs are the original ones.
I figured forward to have 4 wheele drive and back to not engage it. Also Im sure the hubs are the original ones.
It's actually clockwise to lock and counterclockwise to unlock the hubs. If you had the hubs in Auto position, it's probably a vacuum leak or a problem with the hublock solenoid mounted behind the passenger side battery.
The vibration in 4x4 could be a bad driveshaft u-joint. Did you index the driveshaft yokes before you pulled them off, and did you put them back on in the same position?
I did not replace the u-joint in the driveshaft, just the axels in the front.
Well after further investigation I found out what the problem was. Took the lockouts out and did a test drive and still had the vibration. Was sure it was one of the front axle u-joints or the Timken Bearing that I have replaced 3 different times now..... Low and behold it was a u-joint on the rear drive shaft!
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. Drove home and still had vibration, unlocked hubs and still there but not as bad. Dropped the trail and tried to check the 4 wheel drive on a snowy road and nothing.
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