FORD 2009 F-550 v.3 - Manual (Page 307)

can be found in the Maintenance and Specifications chapter. You
should become thoroughly familiar with this information before you
operate your vehicle.
Normal characteristics
On some 4WD models, the initial shift from two-wheel drive to 4x4 while
the vehicle is moving can cause some momentary clunk and ratcheting
sounds. This is the front drivetrain coming up to speed and the
automatic locking hubs engaging and is not cause for concern.
Sand
When driving over sand, try to keep all four wheels on the most solid
area of the trail. Avoid reducing the tire pressures but shift to a lower
gear and drive steadily through the terrain. Apply the accelerator slowly
and avoid spinning the wheels.
Avoid excessive speed because vehicle momentum can work against you
and cause the vehicle to become stuck to the point that assistance may
be required from another vehicle. Remember, you may be able to back
out the way you came if you proceed with caution.
Note: If air is released from your tires, the Tire Pressure Monitoring
System (TPMS) indicator light may illuminate (if equipped).
Mud and water
If you must drive through high
water, drive slowly. Traction or
brake capability may be limited.
When driving through water,
determine the depth; avoid water
higher than the bottom of the hubs
(if possible) and proceed slowly. If
the ignition system gets wet, the
vehicle may stall.
Once through water, always try the brakes. Wet brakes do not stop the
vehicle as effectively as dry brakes. Drying can be improved by moving
your vehicle slowly while applying light pressure on the brake pedal.
Be cautious of sudden changes in vehicle speed or direction when you
are driving in mud. Even 4WD vehicles can lose traction in slick mud. As
when you are driving over sand, apply the accelerator slowly and avoid
spinning your wheels. If the vehicle does slide, steer in the direction of
the slide until you regain control of the vehicle.
If the transmission, transfer case or front axle are submerged in water,
their fluids should be checked and changed, if necessary.
2009 F-250/350/450/550 (f23)
Owners Guide, 3rd Printing
USA (fus)
Driving
307