Hi guys, I have an 09' f-150 xl with a manual on the floor 4x4 lever. When i put it in 4hi on the move or even parked and put it in 4wheel and move forward it just makes a Grinding, clunking noise and vibrates the truck. And sometimes I can't even get it to engage going in reverse before putting it in forward gear.

 

Does it all work fine in 2H and 4Lo?

 

Sounds like your hubs may not be engaging properly. I am not very familiar with the front axle in that model year range but I believe they use vacuum hubs that automatically engage when you shift into 4x4.

 

It goes good in 2hi and in 4lo I have the same issue.

 

Your front hubs are VACUUM controlled.. When the motor is running, the VACUUM pulls the piston and DISENGAGES the front hubs.. When you go into 4 x 4, you break vacuum and the pistons are suppose to move inward and engage the hub. You have o-rings and seals to help things slide smoothly...... I would guess you have partly STUCK pistons.. see if you can narrow down the location of the grinding... front end, left or right.......... you can probably test them with the front wheels off the ground.. idle the motor and the wheels should turn by hand..... put in 4 x 4 and they should LOCK .. see if they grind when turned by hand.

 

I'll give that a try. So even with a manual on the floor 4x4 shifter it still uses vacuum to activate the 4wd?

 

yes, the vacuum disengages the front hubs to allow the wheels to spin freely from the front driveline to help with gas mileage.

 

when you shut the motor off and loose vacuum, the front end pistons move back to the 4 x 4 lock position.. That is SUPPOSE to exercise the system every time you startup...... but things get stuck and sticky.