2008 DODGE RAM 2500 DIESEL coolant temperature

NOTE:High-speed, no-load running of a cold engine
can result in excessive white smoke and poor engine
performance. No-load engine speeds should be kept
under 1,200 rpm during the warm-up period, especially
in cold ambient temperature conditions.
If temperatures are below 32ÉF (0ÉC), operate the engine
at moderate speeds for 5 minutes before full loads are
applied.
Engine Idling
Avoid prolonged idling, long periods of idling may be
harmful to your engine because combustion chamber
temperatures can drop so low that the fuel may not burn
completely. Incomplete combustion allows carbon and
varnish to form on piston rings and injector nozzles.
Also, the unburned fuel can enter the crankcase, diluting
the oil and causing rapid wear to the engine.
CAUTION!
Extended periods of idle time may not allow the
vehicle's exhaust aftertreatment system to properly
regenerate. This can lead to the illumination of the
Malfunction Indicator Light (MIL) or an Electronic
Vehicle Information Center (EVIC) warning message.
Operating the engine for extended periods with the
MIL illuminated or an EVIC warning message dis-
played can cause extensive engine and exhaust sys-
tem damage.
NOTE:Your vehicle is equipped with a turbo speed
limiter, this feature limits the engine speed to 1200 rpm
when engine coolant temperatures are below 70ÉF (21ÉC).
This feature is designed to protect the turbo charger from
damage and will only operate in PARK or NEUTRAL.
278 STARTING AND OPERATING

NOTE:An optional driver-controlled high idle speed is
available on automatic transmission equipped vehicles
with speed control. This feature allows the driver to
select an elevated idle speed between 1100 and 1500
rpms. Your dealer can enable this feature.
The optional driver-controlled high idle speed will help
increase cylinder temperatures and provide additional
cab heat, however, may still cause the exhaust aftertreat-
ment system to not properly regenerate. Extended peri-
ods of idle time should be avoided.
NOTE:
²If ambient temperatures are low and the coolant
temperature is below 200ÉF (93ÉC), the engine idle
speed will slowly increase to 1000 RPM after 2 minutes
of idle, if the following conditions are met:
²foot is off brake pedal and throttle pedal
²automatic transmission is in Park (P)
²vehicle speed is zero
²Applying the throttle will cancel fast idle
²If the engine is equipped with an exhaust brake,
operating the exhaust brake at idle will greatly im-
prove warm up rate and will help keep the engine
close to operating temperature during extended idle.
CAUTION!
Use of aftermarket exhaust brakes is not recom-
mended and could lead to engine damage
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5

Stopping The Engine
Idle the engine a few minutes before routine shutdown.
After full load operation, idle the engine 3 to 5 minutes
before shutting it down. This idle period will allow the
lubricating oil and coolant to carry excess heat away from
the combustion chamber, bearings, internal components,
and turbocharger. This is especially important for turbo-
charged, charge air cooled engines.
NOTE:During engine shutdown on vehicles equipped
with manual transmissions, it is normal for the diesel
engine to resonate heavily for a moment during engine
shut off. When the engine is connected to a manual
transmission, this resonance causes loud gear rattle from
the transmission. This is commonly referred to as ªshut
down rattleº. The manufacturer recommends performing
engine shut down with the clutch pedal pushed to the
floor (clutch disengaged). When engine shut down is
performed in this manner the rattle is reduced (not
eliminated).Driving
ConditionLoadTurbo-
charger
TemperatureIdle Time
(min.) Be-
fore Engine
Shutdown
Stop and
GoEmpty Cool Less than
One
Stop and
GoMedium One
Highway
SpeedsMedium Warm Two
City Traffic Maximum
GCWRThree
Highway
SpeedsMaximum
GCWRFour
Uphill
GradeMaximum
GCWRHot Five
280 STARTING AND OPERATING

Engine Speed Control
CAUTION!
Prevent overspeeding the engine going down hill.
When descending steep grades, use a combination of
gears and service brakes to control vehicle/engine
speed. Overspeed can cause severe engine damage.
Operating Precautions
Avoid Overheating The Engine
The temperature of the coolant (a mixture of 50%
ethylene-glycol and 50% water) must not exceed the
normal range of the temperature gauge (240ÉF/116ÉC)
with a 16 psi (110 kPa) radiator cap.
Usually the coolant temperature indicated during opera-
tion will be to the left of center in the normal range of the
gauge.
Avoid Low Coolant Temperature Operation
Continual operation at low coolant temperature below
the normal range on the gauge (140ÉF/60ÉC) can be
harmful to the engine. Low coolant temperature can
cause incomplete combustion which allows carbon and
varnish to form on piston rings and injector nozzles.
Also, the unburned fuel can enter the crankcase, diluting
the lubricating oil and causing rapid wear to the engine.
Cooling System Tips Ð Automatic Transmission
To reduce potential for engine and transmission over-
heating in high ambient temperature conditions, take the
following actions:
²City Driving Ð
when stopped, put transmission in neutral and increase
engine idle speed.
²Highway Driving Ð
reduce your speed.
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5

²Up Steep Hills Ð
select a lower transmission gear, but try and keep the
torque converter clutch engaged.
²Air Conditioning Ð
turn it off temporarily.
Do Not Operate The Engine With Low Oil
Pressure
When the engine is at normal operating temperature, the
minimum oil pressures required are:
Idle 700 to 800 RPM............... 10psi(69kPa)
Full speed and load.............. 30psi(207 kPa)
CAUTION!
If oil pressure falls to less than normal readings, shut
the engine off immediately. Failure to do so could
result in immediate and severe engine damage.
Do Not Operate The Engine With Failed Parts
Practically all failures give some warning before the parts
fail. Be on the alert for changes in performance, sounds,
and visual evidence that the engine requires service.
Some important clues are:
²engine misfiring or vibrating severely
²sudden loss of power
²unusual engine noises
²fuel, oil or coolant leaks
²sudden change, outside the normal operating range, in
the engine operating temperature
²excessive smoke
²oil pressure drop
282 STARTING AND OPERATING

WARNING!
Do not use the Exhaust Brake feature when driving
in icy or slippery conditions as the increased engine
braking can cause the rear wheels to slide and the
vehicle to swing around with the possible loss of
vehicle control, which may cause an accident possi-
bly resulting in personal injury or death.
NOTE:For optimum braking power it is recommended
to use the Exhaust Brake while in Tow/Haul Mode.
The purpose of the exhaust brake (engine braking) fea-
ture is to supply negative (braking) torque to the engine.
Typically, the engine braking is used for, but not limited
to, vehicle towing applications where vehicle braking can
be achieved by the internal engine power, thereby spar-
ing the mechanical brakes of the vehicle.Benefits of the exhaust brake are:²vehicle driving control
²reduced brake fade
²longer brake life
²faster cab warm-up.
The exhaust brake feature can also be used to reduce the
engine warm up time. To use the exhaust brake as a
warm-up device, the vehicle must be moving less than 5
mph (8 km/h), the exhaust brake switch must be in the
ON position, and the coolant temperature must below
180ÉF (82ÉC) and ambient temperature below 60ÉF (16ÉC).
284 STARTING AND OPERATING

Upshifts into both overdrive gears, 5th and 6th, will be
delayed when the transmission fluid temperature is
below 40É F (4.5É C) or above 240É F (115.5É C).
NOTE:Use caution when operating a heavily loaded
vehicle in 2nd or 1st gear in high ambients as torque
converter slip can impose significant additional heat load
on the cooling system.
WARNING!
Never use Park position on an automatic transmis-
sion as a substitute for the parking brake. Always
apply parking brake fully when parked to guard
against vehicle movement and possible injury or
damage.
Overdrive Operation
The overdrive automatic transmission contains an elec-
tronically controlled 5th and 6th (Overdrive). The trans-
mission will automatically shift from Drive to Overdrive
if the following conditions are present:
²the transmission selector is in DRIVE;
²the engine coolant has reached normal operating tem-
perature;
²vehicle speed is above approximately 30 mph (48
km/h);
²the ªTOW HAUL O/D OFFº switch has not been
activated;
²transmission has reached normal operating tempera-
ture.
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5

Engine Oil Filter
Refer to Fluids, Lubricants and Genuine Parts for the
correct part number. The engine oil filter should be
changed ateveryengine oil change.
Engine Oil And Filter Ð Change
Operate the engine until the coolant temperature reaches
140ÉF (60ÉC). Shut the engine OFF. Remove the oil drain
plug.
Use a container that can hold at least 12 quarts (11.3
Liters) to hold the used oil.
Always check the condition of the used oil. This can give
you an indication of some engine problems that might
exist.
²Thin, black oil indicates fuel dilution.
²Milky discoloration indicates coolant dilution.Clean the area around the oil filter base. Remove the filter
from the underside of the vehicle using a cap style oil
filter wrench.
Clean the gasket surface of the filter mount. The filter
gasket can stick on the filter mount. Make sure it is
removed.
Change the engine oil filter with every engine oil change.
Only a high quality Mopartfilter should be used to
assure most efficient service.
CAUTION!
The filtering medium of other aftermarket filters
may disintegrate. Debris from failed filters may plug
the piston oil cooling nozzles, resulting in scuffed
pistons and engine failure.
416 MAINTAINING YOUR VEHICLE