I have a '99 SD with the V-10, 4WD. It has 188,000 on the OD. SCT tuner. Banks Power PK.
I was towing a small MC trailer to the NC mountains to ride my bike for the weekend. We went over a mountain and started a down hill stretch for a couple of miles. The transmission seemed to fall out of gear toward the bottom of the hill and I had to coast into a RV parking lot. It would rev but acted like it was in neutral. I went thru all the gear options and finally put it into 4WD. I got it to go into reverse at first then finally got it to go into drive. We continued on to the hotel for a couple of miles.
On the way home a couple of days later the trans did the same thing twice. Both times it happened during a long down-hill coast. I should note that I have been experiencing an occasional hard third-gear shift before this happened.
Is this something I can fix with basic mechanic skills or do I need to see the trans doctor?

 

I'm getting some feed back that it may be my transfer case. I have an appointment with the doctor on Thursday and will check back in for the results.

 

Had to cancel my appointment. In the mean time, my 4R100 transmission has bumped into neutral twice more. Both times the vehicle was coasting down hill.
Both times I just pulled over and turned the truck off and cranked it back up and everything works again. I can't find any similarities to other transmission problems that I have read about on here. I'm beginning to think it's electrical? Fluid needs changing for sure but doesn't smell burnt.
Again, it will shift hard into third most of the time but simetimes it has a smoother shift. Not consistent. Going into second and fourth are normal shifts.
Rescheduled my appointment for Thursday but I'm not looking forward to it. Would love to hear a diagnostic from y'all first if possible.

 

keep us posted.


good luck! wish I had something to offer, but I'm simply no help.

 

I've never seen one do this. I can tell you that there is nothing electrical that can make the trans stay in neutral. If the shift handle is in R, D, 2, or 1 the trans will engage in a gear no matter what the electronics are doing, oreven if they are not connected.

 

I guess I'll get some good grease before I take it to the shop.

 

A low fluid level could do that.
On a downhill the fluid is sent to the front of the pan and can leave the pickup sucking air.
Once the vehicle levels out it is ok.
Have a look at the breather because mud wasps have a habit of building nests there.
A clogged breather will cause erroneous fluid levels.

 

I didn't think of that. I think you're right.

 

As of this morning as I was pulling into work the drive system went out completely. I tried repeatedly to get it back into gear but all I hear is a little gear grinding as I put it into park.
Breather seemed ok but I ran a coat hanger in it then blew on it a little just to see if it was clear. I re-checked oil height and it was low so I added a qt. to get it into the checkers then let it continue to idle a few minutes.
I tried putting it into gear it and still nothing. I have a tow truck on the way now to take it to the shop. I will follow up with the diagnosis.

 

I suspect your problem is in the transfer case, not the transmission.

 

Most likely the transfer case. It happen to my expedition.

Something along the main shaft and the electric 4wd selector lever broke in my bw4605 transfer case and cause the neutral issue and gribding in park.

 

It was the transfer case. The trans shop owner couldn't tell me what caused it by looking at it. The only thing that I can contribute to the possible cause would be the hard third gear shifts that occur more and more frequently. Other than that it has not been abused.
Unfortunately, driving it home today from picking it up from the shop it did not feel right. It feels like it is dragging an anchor when I get it up to 65-70 mph. I already called the shop owner and plan to bring it back tomorrow. The transfer case is a reman and comes from a reputable source.
Your thoughts are welcome!

 

Just consider my post here a venue for my venting.
Took it back today and had them test drive it again. Still not sure what it is but speculate that the manual shift linkage mechanism is not adjusted right putting pressure on the shift fork. Just guessing for now.
The other issue with the hard third gear shifts was explained as best as I have been told so far....
Seems that the piston that pushes the clutch plates together is being told to push hard and fast by the computer (increasing oil pressure) because third gear is beginning to go and starting to slip a little. Soon I will need a re-build! I'm sure it can be explained better.
So the saga continues...