I had an odd hiccup from my truck this morning at the boat ramp. Any feedback would be appreciated here.


Context - My truck is a 2016 King Ranch CCLB 4X4 with a 3.55 E locker rear end. I have 223k miles on it. Stock height with 295/65/20 tires on factory wheels.

This morning I towed my boat to the ramp ~75 miles one way. The truck ran great as always on the way down. After backing my boat down the ramp, I set the parking brake and put the truck in park as usual. The truck was left idling.

I launched/tied up the boat and returned to the truck to pull the trailer out of the ramp and park. I put the truck in drive, and it just revved up as if it was still in park. No power was applied to the driveline whatsoever. Keep in mind up to this point, I have been in 2H with no attempt to engage 4x4 or the locker. After a couple of attempts without results, I engaged 4x4 low. The vacuum hubs operated as intended and the front driveline engaged. I was able to get out of the way and to the parking area with power applied to the front wheels only. As you can imagine, the binding on the concrete was ugly, but I had to get out of the way.

Once at the parking spot, I tried several more times to get 2H to engage. During one of the attempts, it seemed to try to engage but there was a nasty noise that came from the transfer case. I think it was the chain slipping.

Now the odd part. I shut the truck off and restarted it. 2H worked perfectly and I recovered the boat and drove home with the truck functioning flawlessly. No noises, no hiccups whatsoever towing the boat all the way back home.

Am I on the right path thinking I may need to rebuild my transfer case before it grenades? Was this just an electrical gremlin? I have a video I can try to post tomorrow showing the driveshaft movement and noise. Thank you in advance for your thoughts on this!

 

….. I was able to get out of the way and to the parking area with power applied to the front wheels only. As you can imagine, the binding on the concrete was ugly, but I had to get out of the way…..

If the rear driveline wasn’t engaged, why was it binding? I think it was engaged, I think the issue was your transmission not going into gear. Maybe low fluid and the ramp, pump couldn’t build pressure.

Id check transmission fluid level.

 

I will check level today along with the transfer case fluid. The binding was in my front driveline from having to use 4x4 low to get to a parking spot. This involved turning on concrete. The rear driveline was not engaged or binding at this time, just the front.

 

Once you got it off the angled ramp surface, did you see if in fact the rear axle was engaged?

Also, thinking about this, do you use your parking brake often? If you’re using your boat a lot, I would think so.

In 153k miles, I have never used mine a d would be afraid to because I would not want it freezing into the engaged position. I'm just trying to rule out the parking brake being partially engaged is all.

At that mileage, when was the last time you changed the trans and transfer case fluids?

As to the grinding from the transfer case, maybe that was due to the angle of the ramp and the fluid being towards the back of the case. Just spit balling here... I am curious to see what happened here.

Good luck.

 

To answer your first question, no it was not engaged. I shifted out of 4L and it was still revving up with no power after pulling off the ramp surface. I engaged 4L again and continued to the parking spot.

I use my parking brake frequently on boat ramps and for my high idle. It’s not sticking, but this sparked some thought. I typically hold the brakes while still in reverse, apply the parking brake, and then shift the transmission into park before releasing the brake pedal. I am thinking that in the early morning haste that I put the truck in park, released the brakes, and THEN engaged the parking brake. This likely put my whole driveline under tension resting on the transmission parking pawl.

I will sheepishly admit that I don’t know if the transmission fluid or t case has been serviced. I will be changing these fluids and diff fluids soon. The transmission fluid is full and looks great. Trans temp towing home yesterday in 90 degree heat never went above 198F.

It is muddy here, so I just went and ran the truck through 2H, Locker, 4HI, and 4L. It functioned flawlessly without a hiccup or any noise. What gives??

Thank you for your thoughts, this is an intriguing discussion!

 

Glad to help... good point about the driveline being under tension...

 

The front axle engaged by itself will not bind. The front axle is an open dif. If you had binding, you had both axles engaged.