Ford Vehicle Manual page 129

Exhaust brake operating characteristics
When you remove your feet from both the accelerator and clutch pedals
and the exhaust brake switch is in the ON position, the exhaust brake is
activated. The following conditions should exist if the brake is operating
properly:
• A slight change in the sound of the engine when the exhaust brake is
activated.
• Exhaust smoke appears normal.
• Engine temperature remains in the normal operating range.
• Road speed usually decreases when the exhaust brake is applied
during a descent, except when the vehicle is carrying a heavy load or
the grade is extremely steep. In these instances, you may need to
apply the service brakes occasionally.
• During a descent, the tachometer usually shows a drop in RPM
depending on the grade and the vehicle load.
• Do not expect a retarding effect similar to sudden hard application of
the service brakes. The exhaust brake retards the vehicle with a
smooth braking effect.
• Depending on the grade and vehicle load, you may or may not feel the
retarding force acting against your body when the brake is applied.
The brake's retarding force is actually preventing the vehicle from
going much faster.
Make sure the exhaust brake is turned off before shutting off the engine.
Installing an exhaust or auxiliary brake should never allow the
engine to exceed maximum governed speeds under any
conditions.
Air brake reservoir draining
Failure to drain air brake reservoirs can result in a reduction or
loss of braking ability due to fluid accumulation in the reservoir
and/or possible freeze-up during cold weather.
Driving
129