2006 MERCEDES-BENZ SPRINTER overheating

COOLING
TABLE OF CONTENTS
page page
COOLING
OPERATION - COOLING SYSTEM...........1
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS.............................1COOLING SYSTEM.....................2
ACCESSORY DRIVE.......................5
ENGINE.................................9
COOLING
OPERATION - COOLING SYSTEM
The cooling system regulates engine operating tem-
perature. It allows the engine to reach normal oper-
ating temperature as quickly as possible. It also
maintains normal operating temperature and pre-
vents overheating.
The cooling system also provides a means of heat-
ing the passenger compartment and cooling the auto-
matic transmission fluid (if equipped). The cooling
system is pressurized and uses a centrifugal water
pump to circulate coolant throughout the system.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - PRELIMINARY
CHECKS
ENGINE COOLING SYSTEM OVERHEATING
Establish what driving conditions caused the com-
plaint. Abnormal loads on the cooling system such as
the following may be the cause:
²PROLONGED IDLE
²VERY HIGH AMBIENT TEMPERATURE
²SLIGHT TAIL WIND AT IDLE
²SLOW TRAFFIC
²TRAFFIC JAMS
²HIGH SPEED OR STEEP GRADES
Driving techniques that avoid overheating are:
²Idle with A/C off when temperature gauge is at
end of normal range.²Increasing engine speed for more air flow is rec-
ommended.
TRAILER TOWING:
Consult Trailer Towing section of owners manual.
Do not exceed limits.
AIR CONDITIONING; ADD - ON OR AFTER MARKET:
A maximum cooling package should have been
ordered with vehicle if add-on or after market A/C is
installed. If not, maximum cooling system compo-
nents should be installed for model involved per
manufacturer's specifications.
RECENT SERVICE OR ACCIDENT REPAIR:
Determine if any recent service has been per-
formed on vehicle that may effect cooling system.
This may be:
²Engine adjustments (incorrect timing)
²Slipping engine accessory drive belt(s)
²Brakes (possibly dragging)
²Changed parts. Incorrect water pump or pump
rotating in wrong direction due to belt not correctly
routed
²Reconditioned radiator or cooling system refill-
ing (possibly under filled or air trapped in system).
NOTE: If investigation reveals none of the previous
items as a cause for an engine overheating com-
plaint, (Refer to 7 - COOLING - DIAGNOSIS AND
TESTING)
VACOOLING 7 - 1

Operate tester pump to apply 103.4 kPa (15 psi)
pressure to system. If hoses enlarge excessively or
bulges while testing, replace as necessary. Observe
gauge pointer and determine condition of cooling sys-
tem according to following criteria:
Holds Steady:If pointer remains steady for two
minutes, serious coolant leaks are not present in sys-
tem. However, there could be an internal leak that
does not appear with normal system test pressure. If
it is certain that coolant is being lost and leaks can-
not be detected, inspect for interior leakage or per-
form Internal Leakage Test.
Drops Slowly:Indicates a small leak or seepage
is occurring. Examine all connections for seepage or
slight leakage with a flashlight. Inspect radiator,
hoses, gasket edges and heater. Seal small leak holes
with a Sealer Lubricant (or equivalent). Repair leak
holes and inspect system again with pressure
applied.
Drops Quickly:Indicates that serious leakage is
occurring. Examine system for external leakage. If
leaks are not visible, inspect for internal leakage.
Large radiator leak holes should be repaired by a
reputable radiator repair shop.
INTERNAL LEAKAGE INSPECTION
Remove engine oil pan drain plug and drain a
small amount of engine oil. If coolant is present in
the pan, it will drain first because it is heavier than
oil. An alternative method is to operate engine for a
short period to churn the oil. After this is done,
remove engine dipstick and inspect for water glob-ules. Also inspect transmission dipstick for water
globules and transmission fluid cooler for leakage.
WARNING: WITH RADIATOR PRESSURE TESTER
TOOL INSTALLED ON RADIATOR, DO NOT ALLOW
PRESSURE TO EXCEED 110 KPA (20 PSI). PRES-
SURE WILL BUILD UP QUICKLY IF A COMBUSTION
LEAK IS PRESENT. TO RELEASE PRESSURE,
ROCK TESTER FROM SIDE TO SIDE. WHEN
REMOVING TESTER, DO NOT TURN TESTER MORE
THAN 1/2 TURN IF SYSTEM IS UNDER PRESSURE.
Operate engine without pressure cap on coolant
container until thermostat opens. Attach a Pressure
Tester to container. If pressure builds up quickly it
indicates a combustion leak exists. This is usually
the result of a cylinder head gasket leak or crack in
engine. Repair as necessary.
If there is not an immediate pressure increase,
pump the Pressure Tester. Do this until indicated
pressure is within system range of 110 kPa (16 psi).
Fluctuation of gauge pointer indicates compression or
combustion leakage into cooling system.
Because the vehicle is equipped with a catalytic
converter,do notremove spark plug cables or short
out cylinders to isolate compression leak.
If the needle on dial of pressure tester does not
fluctuate, race engine a few times to check for an
abnormal amount of coolant or steam. This would be
emitting from exhaust pipe. Coolant or steam from
exhaust pipe may indicate a faulty cylinder head gas-
ket, cracked engine cylinder block or cylinder head.
A convenient check for exhaust gas leakage into
cooling system is provided by a commercially avail-
able Block Leak Check tool. Follow manufacturers
instructions when using this product.
COMBUSTION LEAKAGE TEST - WITHOUT PRES-
SURE TESTER
DO NOT WASTE reusable coolant. If solution is
clean, drain coolant into a clean and suitably marked
container for reuse.
WARNING: Do not remove cylinder block drain
plugs or loosen radiator drain with system hot and
under pressure. serious burns from coolant can
occur.
Drain sufficient coolant to allow thermostat
removal.
Remove accessory drive belt.
Add coolant to pressure container to bring level to
within 6.3 mm (1/4 in) of top of thermostat housing.
CAUTION: Avoid overheating. Do not operate
engine for an excessive period of time. Open drain-
cock immediately after test to eliminate boil over.
Fig. 2 PRESSURE TESTING
1 - PRESSURE RESERVOIR CAP
2 - PRESSURE RESERVOIR
3 - PRESSURE TESTER
VAENGINE 7 - 11

(1) Disconnect the negative battery cable.
(2) Drain the cooling system.
(3) Record the location and snip the wire ties.
(4) Unscrew the engine block heater from the core
plug hole and remove (Fig. 6).
INSTALLATION
(1) Screw the block heater into the core hole (Fig.
6).
(2) Route the heater wiring harness away from
and interference and secure with wiring tie straps.
(3) Refill the cooling system.
(4) Connect the negative battery cable.
(5) Start the engine and inspect for leaks.
ENGINE COOLANT TEMP SEN-
SOR
DESCRIPTION
The ECM determines the operating temperature of
the engine by using the signal from the coolant tem-
perature sensor. The coolant temperature sensor has
a negative temperature coefficient (NTC) resistor
contained in the plastic housing. NTC means; the
higher the temperature, then the lower the resis-
tance. The ECM also uses the coolant temperature
sensor signal to calculate glow plug relay triggering.
If the coolant temperature sensor fails during opera-
tion, the ECM will switch on the cooling fan to pre-
vent engine overheating (A/C models only).
REMOVAL
WARNING: Risk of injury to skin and eyes from
scalding with hot coolant. Risk of poisoning from
swallowing coolant. Do not open cooling system
unless coolant temperature is below 90ÉC. Open
cap slowly to release pressure. Store coolant in
suitable and appropriately marked container. Wear
protective gloves, clothes and eye wear.
(1) Disconnect negative battery cable.
(2) Remove engine cover (Refer to 9 - ENGINE -
REMOVAL).
(3) Partailly drain coolant system (Refer to 7 -
COOLING/ENGINE/COOLANT - STANDARD PRO-
CEDURE).
(4) Unplug coolant temperature sensor electrical
connector.
NOTE: Capture any residual coolant that may flow.
(5) Remove coolant temperature sensor (Fig. 7).
INSTALLATION
WARNING: Risk of injury to skin and eyes from
scalding with hot coolant. Risk of poisoning from
swallowing coolant. Do not open cooling system
unless coolant temperature is below 90ÉC (194ÉF).
Open cap slowly to release pressure. store coolant
in suitable and appropriately marked container.
Wear protective gloves, clothes and eye wear.
(1) Position and install coolant temperature sensor
(Fig. 7).
(2) Connect coolant temperature sensor electrical
connector (Fig. 7).
Fig. 6 ENGINE BLOCK HEATER
1 - ENGINE BLOCK HEATER
2 - CORE PLUG
3 - ENGINE MOUNT
4 - WIRING TIE STRAPS
Fig. 7 ENGINE COOLANT TEMPERATURE SENSOR
1 - RETAINING CLAMP
2 - ENGINE COOLANT TEMPERATURE SENSOR
VAENGINE 7 - 15

Switching Off Main Injection
Main injection is switched off when:
²Engine speed is too high >4700 - 4800 rpm
²Main injection quantity too low
²Low fuel pressure in fuel rail
²Engine off
²External quantity control
²Deceleration mode
Calculating Main Injection
The quantity of main injection is calculated by:
²Engine speed
²Atmospheric pressure
²Coolant temperature
²Boost air temperature
²Fuel rail pressure
²Boost pressure
Period of Actuation
For calculating the period of actuation of the main
injection it is necessary to know whether a pre-injec-
tion has occurred or not.
The coolant temperature, charge air temperature
and the atmospheric pressure are used for correcting
the main injection quantity. If main injection quan-
tity is less than a minimum quantity which is depen-
dent on fuel rail pressure, no preinjection takes
place. In this case, only main injection is performed.
If the quantity is then still below the minimum
quantity, neither main injection or pre-injection takes
place (deceleration mode).
Deceleration Mode
The purpose of the deceleration mode is to inter-
rupt the operation of the injectors. The ECM deter-
mines the accelerator pedal position from a supplied
signal and it determines the engine speed by the
crank sensor. In the overrun and with the engine
speed above 1600, with the accelerator pedal no
pressed, the injectors are no longer actuated and the
fuel rail pressure is lowered by the pressure regula-
tor valve.
Full Load Injected Quantity
The purpose of the full load injected quantity is to
minimize the formation of smoke. The ECM limits
the fuel rail pressure when the engine is operating at
full load by way of the quantity control valve, and
quantity of fuel injected by the injectors. this mini-
mizes the formation of smoke when accelerating and
driving at constant speeds. If a fault occurs at the
boost pressure control, full load injected quantity is
reduced.
Limiting Maximum Engine Speed
The ECM determines the engine speed based on
the signal supplied by the crankshaft sensor and lim-its this by interrupting the operation of the fuel
injectors.
Fuel Quantity Control
The fuel quantity is controlled separately for each
cylinder by the ECM inline with the firing order.The
ECM detects the operating state which exists at the
engine by means of the sensors. In order adapt the
quantity injected, either the fuel rail pressure can be
adjusted by the fuel solenoid and quantity control
valve or the actuation time of the solenoid valves in
the injectors
Boiling Protection
In order to protect against thermal overload and
along with criteria programmed in the ECM, the
injection quantity is reduced as a function of the cool-
ant temperature and vehicle speed. If the coolant
temperature sensor fails the oil temperature signal
from the oil sensor is used as a suitable value.
Fuel Tank Protection
The fuel rail pressure is lowered in order to protect
the fuel tank from overheating. The fuel temperature
sensor measures the temperature of the fuel being
supplied from the tank, in the high pressure flange.
If the fuel is too warm the fuel rail pressure is fur-
ther reduced by the quantity control valve.
STANDARD PROCEDURE
STANDARD PROCEDURE - DRAINING FUEL
TANK - DIESEL
(1) Position a drain hose into the fuel fill opening.
(2) Drain fuel tank using an approved diesel fuel
draining station.
FUEL CONTAMINATION
If a diesel engine's fuel supply has been contami-
nated with gasoline, the following procedure must be
followed:
(1) Remove all fuel from the fuel tank. (Refer to 14
- FUEL SYSTEM/FUEL DELIVERY - STANDARD
PROCEDURE-DRAINING FUEL TANK) Use an
appropriate fuel container. Dispose of the contami-
nated fuel using the proper procedures.
CAUTION: Dispose of petroleum based products in
a manner consistent with all applicable Local, State,
Federal, and Provincial regulations.
(2) Remove and clean fuel tank. (Refer to 14 -
FUEL SYSTEM/FUEL DELIVERY/FUEL TANK -
REMOVAL)
(3) Install the fuel tank. (Refer to 14 - FUEL SYS-
TEM/FUEL DELIVERY/FUEL TANK - INSTALLA-
TION)
14 - 8 FUEL DELIVERYVA

FLUID AND FILTER
DESCRIPTION
The oil level control (Fig. 147) is located on the
electrohydraulic unit (4) and consists of the float (5)
which is integrated into the electrohydraulic unit.
The float is positioned to plug the opening (6)
between the oil gallery (2) and gearset chamber (1) so
that the rotating gearsets do not splash about in oil
as the oil level rises. The oil level control reduces
power loss and prevents oil from being thrown out of
the transmission housing at high oil temperatures.
OPERATION
With low oil levels, the lubricating oil which flows
constantly out of the gearset, flows back to oil gallery
(2) though the opening (6). (Fig. 148) If the oil level
rises, the oil presses the float (5) against the housing
opening (6). The float (5) therefore separates the oil
gallery (2) from the gearset chamber (1). The lubri-
cating oil which continues to flow out of the gearsets
is thrown against the housing wall, incorporated by
the rotating parts and flows back into the oil gallery
(2) through the upper opening (arrow).
DIAGNOSIS AND TESTING
EFFECTS OF INCORRECT FLUID LEVEL
A low fluid level allows the pump to take in air
along with the fluid. Air in the fluid will cause fluid
pressures to be low and develop slower than normal.
If the transmission is overfilled, the gears churn the
fluid into foam. This aerates the fluid and causing
the same conditions occurring with a low level. In
either case, air bubbles cause fluid overheating, oxi-
dation, and varnish buildup which interferes with
valve and clutch operation. Foaming also causes fluid
expansion which can result in fluid overflow from the
transmission vent or fill tube. Fluid overflow can eas-
ily be mistaken for a leak if inspection is not careful.
Fig. 147 Fluid Level Control
1 - GEARSET CHAMBER
2 - OIL GALLERY
3 - SHELL OF ELECTROHYDRAULIC UNIT
4 - ELECTROHYDRAULIC UNIT
5 - FLOAT
6 - OPENING
Fig. 148 Fluid Level Control
1 - GEARSET CHAMBER
2 - OIL GALLERY
3 - SHELL OF ELECTROHYDRAULIC UNIT
4 - ELECTROHYDRAULIC UNIT
5 - FLOAT
6 - OPENING
VAAUTOMATIC TRANSMISSION NAG1 - SERVICE INFORMATION 21 - 131

CAUSES OF BURNT FLUID
Burnt, discolored fluid is a result of overheating
which has three primary causes.
1. Internal clutch slippage, usually caused by low
line pressure, inadequate clutch apply pressure, or
clutch seal failure.
2. A result of restricted fluid flow through the
main and/or auxiliary cooler. This condition is usu-
ally the result of a faulty or improperly installed
drainback valve, a damaged oil cooler, or severe
restrictions in the coolers and lines caused by debris
or kinked lines.
3. Heavy duty operation with a vehicle not prop-
erly equipped for this type of operation. Trailer tow-
ing or similar high load operation will overheat the
transmission fluid if the vehicle is improperly
equipped. Such vehicles should have an auxiliary
transmission fluid cooler, a heavy duty cooling sys-
tem, and the engine/axle ratio combination needed to
handle heavy loads.
FLUID CONTAMINATION
Transmission fluid contamination is generally a
result of:
²adding incorrect fluid
²failure to clean dipstick and fill tube when
checking level
²engine coolant entering the fluid
²internal failure that generates debris
²overheat that generates sludge (fluid break-
down)
²failure to replace contaminated converter after
repair
The use of non-recommended fluids can result in
transmission failure. The usual results are erratic
shifts, slippage, abnormal wear and eventual failure
due to fluid breakdown and sludge formation. Avoid
this condition by using recommended fluids only.
The dipstick cap and fill tube should be wiped
clean before checking fluid level. Dirt, grease and
other foreign material on the cap and tube could fall
into the tube if not removed beforehand. Take the
time to wipe the cap and tube clean before withdraw-
ing the dipstick.
Engine coolant in the transmission fluid is gener-
ally caused by a cooler malfunction. The only remedy
is to replace the radiator as the cooler in the radiator
is not a serviceable part. If coolant has circulated
through the transmission, an overhaul is necessary.
The torque converter should be replaced whenever
a failure generates sludge and debris. This is neces-
sary because normal converter flushing procedures
will not remove all contaminants.
STANDARD PROCEDURE
CHECK OIL LEVEL
(1) Verify that the vehicle is parked on a level sur-
face.
(2) Remove locking pin (1) (Fig. 149). Remove the
plate of the locking pin with a suitable tool and press
out the pin remaining in the cap downwards.
(3) Remove cap (2).
WARNING: Risk of accident from vehicle starting off
by itself when engine running. Risk of injury from
contusions and burns if you insert your hands into
the engine when it is started or when it is running.
Secure vehicle to prevent it from moving off by
itself. Wear properly fastened and close-fitting work
clothes. Do not touch hot or rotating parts.
(4) Actuate the service brake. Start engine and let
it run at idle speed in selector lever position ªPº.
(5) Shift through the transmission modes several
times with the vehicle stationary and the engine
idling
(6) Warm up the transmission, wait at least 2 min-
utes and check the oil level with the engine running.
Push the Oil Dipstick 8863A in up to the stop on the
electrohydraulic unit and pull out again, read off oil
level, repeat if necessary.
NOTE: The dipstick will protrude from the fill tube
approximately 75mm (3 inches) when installed.
Fig. 149 Remove Dipstick Tube Cap Lock
1 - LOCKING PIN
2 - TUBE CAP
3 - DIPSTICK TUBE
21 - 132 AUTOMATIC TRANSMISSION NAG1 - SERVICE INFORMATIONVA

Condition Possible Causes Correction
The low side pressure is
normal or slightly low, and
the high side pressure is too
low.1. Low refrigerant system
charge.1. See Refrigerant System Leaks in this
group. Test the refrigerant system for leaks.
Repair, evacuate and charge the refrigerant
system, if required.
2. Refrigerant flow through the
A/C evaporator is restricted.2. See A/C Evaporator in this group. Replace
the restricted A/C evaporator, if required.
3. Faulty A/C compressor. 3. See A/C Compressor in this group. Re-
place the A/C compressor, if required.
The low side pressure is
normal or slightly high, and
the high side pressure is too
high.1. A/C condenser air flow re-
stricted.1. Check the A/C condenser for damaged
fins, foreign objects obstructing air flow
through the condenser fins, and missing or
improperly installed air seals. Clean, repair, or
replace components as required.
2. Refrigerant flow through the
receiver/drier is restricted.2. See Receiver/Drier in this group. Replace
the restricted receiver/drier, if required.
3. Inoperative radiator cooling
fan.3. Test the radiator cooling fan and replace, if
required. Refer to Group 7 - Cooling.
4. Refrigerant system over-
charged.4. See Refrigerant System Charge in this
group. Recover the refrigerant from the refrig-
erant system. Charge the refrigerant system
to the proper level, if required.
5. Air in the refrigerant system. 5. See Refrigerant System Leaks in this
group. Test the refrigerant system for leaks.
Repair, evacuate and charge the refrigerant
system, if required.
6. Engine overheating. 6. Test the engine cooling system and repair,
if required. Refer to Group 7 - Cooling.
The low side pressure is too
high, and the high side pres-
sure is too low.1. Accessory drive belt slip-
ping.1. Inspect the accessory drive belt condition
and tension. Repair as required. Refer to
Group 7 - Cooling.
2. Faulty A/C expansion valve. 2. See A/C Expansion Valve in this group.
Replace the valve, if required.
3. Faulty A/C compressor. 3. See A/C Compressor in this group. Re-
place the A/C compressor, if required.
The low side pressure is too
low, and the high side pres-
sure is too high.1. Restricted refrigerant flow
through the refrigerant lines.1. See Liquid Line, Suction Line and Dis-
charge Line in this group. Inspect the refriger-
ant lines for kinks, tight bends or improper
routing. Correct the routing or replace the re-
frigerant line, if required.
2. Restricted refrigerant flow
through the A/C expansion
valve.2. See A/C Expansion Valve in this group.
Replace the valve, if required.
3. Restricted refrigerant flow
through the A/C condenser.3. See A/C Condenser in this group. Replace
the restricted A/C condenser, if required.
HEATER PERFORMANCE TEST
Before performing the following tests, perform the
ATC Function Test using the DRBIIItand refer to
Cooling for the procedures to check the radiator cool-
ant level, serpentine drive belt tension, radiator air
flow and the radiator fan operation.
MAXIMUM HEATER OUTPUT
Engine coolant is provided to the heater core
through a heater valve and heater hose. With the
engine idling at normal operating temperature, set
the heater-A/C controls as follows:
²Temperature control in the full hot position
VAHEATING & AIR CONDITIONING 24 - 5

²Disconnect the live test lead before disconnecting
the common test lead.
²When using the meter function, keep the
DRBIIItaway from spark plug or coil wires to
avoid measuring error from outside interference.
4.3 WARNINGS
4.3.1 VEHICLE DAMAGE WARNINGS
Before disconnecting any control module, make
sure the ignition is9lock9position. Failure to do so
could damage the module.
When testing voltage or continuity at any control
module, use the terminal side (not the wire end) of
the connector. Do not probe a wire through the
insulation: this will damage the wire and eventu-
ally cause the wire to fail because of corrosion.
Be careful when performing electrical tests so as
to prevent accidental shorting of terminals. Such
mistakes can damage fuses or components. Also, a
second DTC could be set, making diagnosis of the
original problem more difficult.
When replacing a blown fuse, it is important to
use only a fuse having the correct amperage rating.
The use of a fuse with a rating other than indicated
may result in a dangerous electrical system over-
load. If a properly rated fuse continues to blow, it
indicates a problem in the circuit that must be
corrected.
4.3.2 ROAD TESTING A COMPLAINT
VEHICLE
Some complaints will require a test drive as part
of the repair verification procedure. The purpose of
the test drive is to try to duplicate the diagnostic
DTC or symptom condition.
CAUTION: Before road testing a vehicle, be
sure that all components are reassembled.
During the test drive, do not try to read
DRBIIITscreen while in motion. Do not hang
the DRBIIITfrom the rear view mirror or
operate it yourself. Have an assistant
available to operate the DRBIIIT.
Road testing is an essential step in the diagnostic
process that must not be overlooked. Along with the
diagnostic information obtained from the DRBIIIt
Scan Tool and the original customer concern, the
road test helps verify the problem was current and
any repairs performed, fixed the vehicle correctly.
Always operate and observe the vehicle under ac-
tual driving conditions.
Just as important as the road test is, there are
preliminary inspections that should be performed
prior to the road test. Always check the fluid leveland condition before taking the vehicle on a road
test. Determine if the incorrect fluid is being used,
improper fluid will result in erratic transmission
operation.
Some of the conditions of incorrect fluid level are as
follows:
²Delayed engagement
²Poor shifting or erratic shifting
²Excessive noise
²Overheating
The next step is to verify that the shift linkage is
correctly adjusted. If the shift linkage is incorrectly
adjusted, a number of complaints can result.
The TCM monitors the Shift Lever Position (SLP)
continuously. If the linkage is incorrectly adjusted,
the TCM will sense a shift lever position that is not
correct for the gear chosen by the driver. This may
cause a DTC to be set.
The following complaints may also be the result of
an incorrectly adjusted or worn linkage:
²Delayed clutch engagement
²Erratic shifts
²Vehicle will drive in neutral
²Engine will not crank in park or neutral
²Gear shift linkage will be able to be shifted
without the key in the ignition
²Not able to remove the ignition key in park
²Parking pawl will not engage properly
The shift linkage should also be adjusted when
replacing the Transmission, repairing the valve
body, or when repairing any component between the
shift lever and the Transmission.
Some questions to ask yourself when performing
the road test are as follows:
²Is the complaint or concern what you think the
problem is, based on the drivers description of the
problem?
²Is the Transmission operating normally, or is
there a real problem?
²When does the problem occur?
²Is the problem only in one gear range?
²What temperature does the problem occur?
²Does the vehicle have to sit over night for the
problem to occur?
²Does the transmission go into Limp-in mode?
4.4.4 BULLETINS AND RECALLS
Always perform all Safety Recalls and Technical
Service Bulletins that are applicable to the prob-
lem.
7
GENERAL INFORMATION