Clutch slipping, or...?

I'm having a major issue with my company truck and It is proving hard to diagnose. I hope you guys can help me understand the possible causes of my symptoms. I'm going to try not to be too wordy, but I need to explain a timeline of behavior. Thanks in advance, for reading and for any help you can provide.

First things first: My truck is a 2013 Freightliner Cascadia with DD13 engine and an Eaton 10 speed. It has 200,000 miles on it.

My truck was assigned to me on August 20th. Less than a week later, while driving through the rolling hills on I 95 east of DC, I experienced my issue for the first time. With a full load behind me (liquid in a tanker) and with the throttle down to merge or climb a hill, I suddenly felt something slipping in the drivetrain. Just like trying to gain traction on ice, my RPMs shot up, while my speed went down. My company rerouted me to an operations center where, the next day, they had someone test drive my truck (with me as passenger) and, sure enough, the problem did not reappear. I continued driving the truck without issues for the next few weeks. Then the problem reappeared. I had been sitting, idling for at least 12 hours when an assignment came through and I proceeded, bobtail, to pick up a load. Leaving the parking lot I immediately sensed slipping again. On level ground, if I blipped the throttle the rpm would go up with no increase in speed. Only the most gradual throttle application increased my speed. I limped a couple of miles and things got worse. I almost couldn't make it up an entrance ramp to a highway (bobtailing!) there was so much slippage. Keep in mind, I had not been driving, only parked idling, in the time leading up to this.

My company routed me to a Freightliner dealership. A mechanic test drive the truck and reported it needed a new clutch. They put one in, and I felt vindicated. When I got the truck back I drove it for 10 days or so without issues...until 2 days ago. Climbing the Appalachians on i64 in West Virginia, I started experiencing slippage again. As before, Rpm shot up, speed dropped and there was a shudder in the drivetrain. Each time this occurred I immediately eased off the throttle and had to drop a gear but the problem only got more constant as I kept driving. Twice I stopped and let the truck cool down for 1/2 -1 hour. That helped each time. I was able to proceed a few more miles, even uphill, without issue before the problem reappeared.

I even experienced slippage on a steep downgrade. With engine brake on high and having dropped to a lower gear, I descended a steep grade only to notice the rpm drop to idle while my truck gained speed! Not fun.

Eventually the problem got so bad I was reduced to trying to complete a climb in FIRST GEAR after losing all momentum. Even that was not to be, as I rolled to a complete stop just shy of the crest of the mountain. At that point I could leave the truck in gear without depressing the cutch at all and there was no stalling, nor forward momentum.

I had the truck towed to a dealer. The last report I received was that the technician didn't find anything wrong...

Folks, I can't have this. It has put me in danger and cost me money in down time. I'm ready to demand either a clear discovery and repair of the problem or a new truck assignment.

Can any of you speculate on what is going on? Is there something beside the clutch itself that can cause slipping in the drivetrain?

 

I appreciate both your sentiments about driving til it breaks. The thing is it has broken, if breakage is defined as the truck failing to move under its own power.

Part of the reason I'm seeking input on this is because of the tendency to blame this sort of phenomenon on the driver, either in the form of irregular driving habits or worse, as figments of the driver's imagination.

 

No air bag gauge. I was wondering about that too, but have never been able to visually confirm whether any wheel is spinning. I'd did, however, engage the differential lock during one of my low speed slippage incidents and it didn't seem to help any...

 

Will do. Thanks.