Dodge Nitro. Manual — part 57

2. Raise and support the vehicle.

3. Remove the bolts and nuts attaching the exhaust pipe to the engine exhaust manifold.

4. Lower the vehicle.

5. Remove the exhaust heat shields (1).

6. Remove bolts, nuts and washers attaching manifold to cylinder head.

7. Remove manifold. See Fig. 168 and gasket from the cylinder head.

INSTALLATION

EXHAUST MANIFOLD

RIGHT EXHAUST MANIFOLD

1. Position the engine exhaust manifold and gasket on the two studs located on the cylinder head. Install

conical washers and nuts on these studs.

2. Install remaining conical washers. Starting at the center arm and working outward, tighten the bolts and

nuts to 25 N.m (18 ft. lbs.)

3. Install the exhaust heat shields.

4. Raise and support the vehicle.

5. Assemble exhaust pipe to manifold and secure with bolts, nuts and retainers. Tighten the bolts and nuts to

34 N.m (25 ft. lbs.)

LEFT EXHAUST MANIFOLD

1. Position the engine exhaust manifold and gasket on the two studs located on the cylinder head. Install

conical washers and nuts on these studs.

2. Install remaining conical washers. Starting at the center arm and working outward, tighten the bolts and

nuts to 25 N.m (18 ft. lbs.)

3. Install the exhaust heat shields.

4. Raise and support the vehicle.

CAUTION: If the studs came out with the nuts when removing the engine exhaust

manifold, install new studs. Apply sealer on the coarse thread ends. Water
leaks may develop at the studs if this precaution is not taken.

CAUTION: Over tightening heat shield fasteners, may cause shield to distort

and/or crack.

CAUTION: If the studs came out with the nuts when removing the engine exhaust

manifold, install new studs. Apply sealer on the coarse thread ends. Water
leaks may develop at the studs if this precaution is not taken.

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro

5. Assemble exhaust pipe to manifold and secure with bolts, nuts and retainers. Tighten the bolts and nuts to

34 N.m (25 ft. lbs.)

VALVE TIMING

DESCRIPTION

TIMING DRIVE

Fig. 169: Timing Drive System
Courtesy of CHRYSLER LLC

CAUTION: Over tightening heat shield fasteners, may cause shield to distort

and/or crack.

1 - RIGHT CAMSHAFT SPROCKET AND SECONDARY CHAIN
2 - SECONDARY TIMING CHAIN TENSIONER (LEFT AND RIGHT SIDE NOT
INTERCHANGEABLE)
3 - SECONDARY TENSIONER ARM
4 - LEFT CAMSHAFT SPROCKET AND SECONDARY CHAIN
5 - CHAIN GUIDE (LEFT AND RIGHT SIDE ARE NOT INTERCHANGEABLE)
6 - PRIMARY CHAIN

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro

The timing drive system. See Fig. 169 has been designed to provide quiet performance and reliability to support
a non-free wheeling engine. Specifically the intake valves are non-free wheeling and can be easily damaged
with forceful engine rotation if camshaft-to-crankshaft timing is incorrect. The timing drive system consists of a
primary chain (6), two secondary timing chain drives (1,4) and a counterbalance shaft drive.

OPERATION

TIMING DRIVE

The primary timing chain is a single inverted tooth chain type. The primary chain drives the large 50 tooth idler
sprocket directly from a 25 tooth crankshaft sprocket. Primary chain motion is controlled by a pivoting leaf
spring tensioner arm and a fixed guide. The arm and the guide both use nylon plastic wear faces for low friction
and long wear. The primary chain receives oil splash lubrication from the secondary chain drive and designed
oil pump leakage. The idler sprocket assembly connects the primary chain drive, secondary chain drives, and
the counterbalance shaft. The idler sprocket assembly consists of two integral 26 tooth sprockets a 50 tooth
sprocket and a helical gear that is press-fit to the assembly. The spline joint for the 50 tooth sprocket is a non
serviceable press fit anti rattle type. The idler sprocket assembly spins on a stationary idler shaft. The idler shaft
is a light press-fit into the cylinder block. A large washer on the idler shaft bolt and the rear flange of the idler
shaft are used to control sprocket thrust movement. Pressurized oil is routed through the center of the idler shaft
to provide lubrication for the two bushings used in the idler sprocket assembly.

There are two secondary drive chains, both are roller type, one to drive the camshaft in each SOHC cylinder
head. There are no shaft speed changes in the secondary chain drive system. Each secondary chain drives a 26
tooth cam sprocket directly from the 26 tooth sprocket on the idler sprocket assembly. A fixed chain guide and a
hydraulic oil damped tensioner are used to maintain tension in each secondary chain system. The hydraulic
tensioners for the secondary chain systems are fed pressurized oil from oil reservoir pockets in the block. Each
tensioner incorporates a controlled leak path through a device known as a vent disc located in the nose of the
piston to manage chain loads. Each tensioner also has a mechanical ratchet system that limits chain slack if the
tensioner piston bleeds down after engine shut down. The tensioner arms and guides also utilize nylon wear
faces for low friction and long wear. The secondary timing chains receive lubrication from a small orifice in the
tensioners. This orifice is protected from clogging by a fine mesh screen which is located on the back of the
hydraulic tensioners.

STANDARD PROCEDURE

TIMING VERIFICATION

7 - IDLER SPROCKET
8 - CRANKSHAFT SPROCKET
9 - PRIMARY CHAIN TENSIONER

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro

Fig. 170: Timing Chain Cover & Crankshaft Timing Marks
Courtesy of CHRYSLER LLC

1 - TIMING CHAIN COVER
2 - CRANKSHAFT TIMING MARKS

CAUTION: The 3.7L is a non free-wheeling design engine. Therefore, correct engine

timing is critical.

NOTE:

Components referred to as left hand or right hand are as viewed from the
drivers position inside the vehicle.

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro