MeredithB2019

Hi all,
My friend has a 2008 F150 4x4 (shift ****) issues. Here is what happens:

From neutral, he will turn **** to 4L, no noises at this point.
Shifts to D, but once he gets a little speed there is a loud front end clunk and the 4x4 disengages automatically. If it is not shifted back to 2x4, it will make a grinding noise until switched back to 2x4.

Any ideas? Thanks in advance!

03 Heritage Edition

Shouldn't be driving too fast in 4L. 4L is the lower speed, granny torque/power mode of 4WD. Want to consistently drive 25mph or faster, put it in 4H.

Gale Hawkins

What is the age and condition of the transfer case fluid. I had one not used much I expect when I got it and did everything at relative low speed in a one acre gravel parking lot until it got to shifting better. Then we changed out the transfer case fluid and added a few ounces of Archoil AR9100 additive that some Ford diesel owners like in their engines for extra protection.

MeredithB2019

Sorry, I meant 4H not Low

techrep

iTrader: (1)

Sounds like he needs some new IWE's to me but, without troubleshooting first it's hard to say for sure.

FordFrenzy06

FYI You don't have to be in neutral to shift into 4H.

Gossamer

This could be related to a common F-150 4x4 issue where water has made its way into the hubs.
The vacuum solenoids mounted on the firewall get dripped on from the front cowl, and water then travels down the lines & into the hubs. There is an after-market mounting bracket that covers the top of the solenoid to prevent this.
Like the others said, this is very hard to tell without seeing or hearing it, this is just something to check.

Mine did make some grinding noise similar to what you described with 4x4 engaged, and that led me to the water in the hubs