Dodge Nitro. Manual — part 530

Fig. 79: Cutaway View Of Thermostat & Bypass
Courtesy of CHRYSLER LLC

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro

The 3.7L engine uses an internal water/coolant bypass system. The design uses galleries in the timing chain
cover to circulate coolant during engine warm-up preventing the coolant from flowing through the radiator. The
thermostat uses a stub shaft located at the rear of the thermostat to control flow through the bypass gallery.

DESCRIPTION-3.7L

Fig. 80: Identifying Integral Water Pump Pulley, Timing Chain Covering, Thermostat Housing & Water

1 - FROM HEATER
2 - FROM RADIATOR
3 - TO WATER PUMP
4 - ENGINE BYPASS
5 - THERMOSTAT

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro

Pump
Courtesy of CHRYSLER LLC

A centrifugal water pump (5) circulates coolant through the water jackets, passages, intake manifold, radiator
core, cooling system hoses and heater core. The pump is driven from the engine crankshaft by a single
serpentine drive belt.

The water pump impeller is pressed onto the rear of a shaft that rotates in bearings pressed into the housing. The
housing has two small holes to allow seepage to escape. The water pump seals are lubricated by the antifreeze
in the coolant mixture. No additional lubrication is necessary.

Both heater hoses are connected to fittings on the timing chain front cover. The water pump is also mounted
directly to the timing chain cover and is equipped with an integral pulley.

WATER PUMP-DESCRIPTION-2.8L DIESEL

Fig. 81: Identifying Water Pump
Courtesy of CHRYSLER LLC

The water pump on the 2.8L diesel has a die cast aluminum housing. It bolts directly to the engine block.

OPERATION

OPERATION-3.7L

1 - INTEGRAL WATER PUMP PULLEY
2 - TIMING CHAIN COVER
3 - THERMOSTAT HOUSING
4 - HEATER HOSE FITTINGS
5 - WATER PUMP

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro

A centrifugal water pump circulates coolant through the water jackets, passages, intake manifold, radiator core,
cooling system hoses and heater core, this coolant absorbs the heat generated when the engine is running. The
pump is driven by the engine crankshaft via a drive belt.

WATER PUMP-OPERATION-2.8L DIESEL

The water pump is used to circulate coolant through the cooling system. The coolant is pumped through the
engine block, cylinder head, heater core, EGR cooler, viscous heater, and radiator.

REMOVAL

REMOVAL-3.7L ENGINE

Fig. 82: Identifying Special Tool 6958 Spanner Wrench With Adapter Pins 8346 & Fan
Courtesy of CHRYSLER LLC

2007 Dodge Nitro R/T

2007 ENGINE Cooling - Nitro