FORD 1999 F-550 v.1 - Manual (Page 134)

Sand
When driving over sand, try to keep all four wheels on the most solid
area of the trail. Do not reduce the tire pressures but shift to a lower
gear and drive steadily through the terrain. Apply the accelerator slowly
and avoid spinning the wheels.
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.
After driving through mud, clean off residue stuck to rotating driveshafts
and tires. Excess mud stuck on tires and rotating driveshafts causes an
imbalance that could damage drive components.
If the transmission, transfer case or front axle are submerged in water,
their fluids should be checked and changed, if necessary.
Water intrusion into the transmission may damage the
transmission.
If the front or rear axle is submerged in water, the axle lubricant should
be replaced.
Driving on hilly or sloping terrain
When driving on a hill, avoid driving crosswise or turning on steep
slopes. You could lose traction and slip sideways. Drive straight up,
straight down or avoid the hill completely. Know the conditions on the
other side of a hill before driving over the crest.
When climbing a steep hill, start in a lower gear rather than downshifting
to a lower gear from a higher gear once the ascent has started. This
reduces strain on the engine and the possibility of stalling.
When descending a steep hill, avoid sudden braking. Shift to a lower gear
when added engine braking is desired.
When speed control is on and you are driving uphill, your vehicle speed
may drop considerably, especially if you are carrying a heavy load.
Driving
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