Dodge Nitro. Manual — part 22

4. For rocker arm removal on cylinders No. 3 and No. 5, Rotate the crankshaft until cylinder No. 1 is at

TDC exhaust stroke.

5. For rocker arm removal on cylinders No. 2 and No. 6, Rotate the crankshaft until cylinder No. 1 is at

TDC ignition stroke.

6. Using the Rocker Arm Remover/Installer 8516A. See Fig. 67 (2) , press downward on the valve spring,

remove rocker arm.

SEALS-VALVE GUIDE

DESCRIPTION

VALVE GUIDE SEAL

The valve guide seals are made of rubber and incorporate an integral steel valve spring seat. The integral garter
spring maintains consistent lubrication control to the valve stems.

SPRINGS-VALVE

DESCRIPTION

VALVE SPRINGS

The valve springs are made from high strength chrome silicon steel. The springs are NOT common for intake
and exhaust applications. The exhaust spring has an external damper. The valve spring seat is integral with the
valve stem seal, which is a positive type seal to control lubrication.

REMOVAL

VALVE SPRINGS

1. Remove the cylinder head cover. See REMOVAL).

2. Using the Valve Spring Remover/Installer 8516A, remove the rocker arms and the hydraulic lash

adjusters.

3. Remove the spark plug for the cylinder the valve spring and seal are to be removed from.

4. Apply shop air to the cylinder to hold the valves in place when the spring is removed.

5. Using the Valve Spring Compressor 8387, compress the valve spring.

6. Remove the two spring retainer lock halves.

NOTE:

All six valve springs and seals are removed in the same manner; this
procedure only covers one valve seal and valve spring.

NOTE:

It may be necessary to tap the top of the valve spring to loosen the spring
retainers locks enough to be removed.

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro

7. Remove the valve spring compressor.

8. Remove the spring retainer, and the spring.

9. Remove the valve stem seal.

INSTALLATION

VALVE SPRINGS

1. Apply shop air to the cylinder to hold the valves in place while the spring is installed.

2. Install the valve stem seal.

3. Install the spring retainer, and the spring.

4. Using the Valve Spring Compressor 8387, compress the valve spring.

5. Install the two spring retainer lock halves.

6. Remove the valve spring compressor.

7. Disconnect the shop air to the cylinder.

8. Install the spark plug for the cylinder the valve spring and seal was installed on.

9. Using Valve Spring Remover/Installer 8516, install the rocker arms and the hydraulic lash adjusters.

10. Install the cylinder head cover. See INSTALLATION).

CYLINDER HEAD - RIGHT

NOTE:

The valve spring is under tension use care when releasing the valve spring
compressor.

NOTE:

The valve springs are NOT common between intake and exhaust.

NOTE:

The valve stem seals are common between intake and exhaust.

NOTE:

All six valve springs and seals are removed in the same manner; this procedure
only covers one valve seal and valve spring.

NOTE:

The valve stem seals are common between intake and exhaust.

NOTE:

The valve springs are NOT common between intake and exhaust.

NOTE:

The valve spring is under tension use care when releasing the valve spring
compressor.

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro

DESCRIPTION

VALVE GUIDES

The valve guides are made of powered metal and are pressed into the cylinder head. The guides are not
replaceable or serviceable, and valve guide reaming is not recommended. If the guides are worn beyond
acceptable limits, replace the cylinder heads.

VALVES

The valves are made of heat resistant steel and have chrome plated stems to prevent scuffing. Each valve is
actuated by a roller rocker arm which pivots on a stationary lash adjuster. All valves use three bead lock keepers
to retain the springs and promote valve rotation.

CYLINDER HEAD

The cylinder heads are made of an aluminum alloy. The cylinder head features two valves per cylinder with
pressed in powdered metal valve guides. The cylinder heads also provide enclosures for the timing chain drain,
necessitating unique left and right cylinder heads.

DIAGNOSIS AND TESTING

HYDRAULIC LASH ADJUSTER

A tappet-like noise may be produced from several items. Check the following items.

1. Engine oil level too high or too low. This may cause aerated oil to enter the adjusters and cause them to

be spongy.

2. Insufficient running time after rebuilding cylinder head. Low speed running up to 1 hour may be required.

3. Turn engine off and let set for a few minutes before restarting. Repeat this several times after engine has

reached normal operating temperature.

4. Low oil pressure.

5. The oil restrictor in cylinder head gasket or the oil passage to the cylinder head is plugged with debris.

6. Air ingested into oil due to broken or cracked oil pump pick up.

7. Worn valve guides.

8. Rocker arm ears contacting valve spring retainer.

9. Rocker arm loose, adjuster stuck or at maximum extension and still leaves lash in the system.

10. Oil leak or excessive cam bore wear in cylinder head.

11. Faulty lash adjuster.

Check lash adjusters for sponginess while installed in cylinder head and cam on camshaft at base
circle. Depress part of rocker arm over adjuster. Normal adjusters should feel very firm. Spongy
adjusters can be bottomed out easily.

Remove suspected lash adjusters, and replace.

Before installation, make sure adjusters are at least partially full of oil. This can be verified by little

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro

or no plunger travel when lash adjuster is depressed.

CYLINDER HEAD GASKET

A cylinder head gasket leak can be located between adjacent cylinders or between a cylinder and the adjacent
water jacket.

Possible indications of the cylinder head gasket leaking between adjacent cylinders are:



Loss of engine power



Engine misfiring



Poor fuel economy

Possible indications of the cylinder head gasket leaking between a cylinder and an adjacent water jacket are:



Engine overheating



Loss of coolant



Excessive steam (white smoke) emitting from exhaust



Coolant foaming

CYLINDER-TO-CYLINDER LEAKAGE TEST

To determine if an engine cylinder head gasket is leaking between adjacent cylinders, follow the procedures in
Cylinder Compression Pressure Test. See DIAGNOSIS AND TESTING. An engine cylinder head gasket
leaking between adjacent cylinders will result in approximately a 50 - 70% reduction in compression pressure.

CYLINDER-TO-WATER JACKET LEAKAGE TEST

VISUAL TEST METHOD

With the engine cool, remove the coolant pressure cap. Start the engine and allow it to warm up until thermostat
opens.

If a large combustion/compression pressure leak exists, bubbles will be visible in the coolant.

COOLING SYSTEM TESTER METHOD

WARNING:

USE EXTREME CAUTION WHEN THE ENGINE IS OPERATING WITH
COOLANT PRESSURE CAP REMOVED.

WARNING:

WITH COOLING SYSTEM TESTER IN PLACE, PRESSURE WILL BUILD UP
FAST. EXCESSIVE PRESSURE BUILT UP, BY CONTINUOUS ENGINE
OPERATION, MUST BE RELEASED TO A SAFE PRESSURE POINT.
NEVER PERMIT PRESSURE TO EXCEED 138 kPa (20 psi).

2007 Dodge Nitro R/T

2007 ENGINE 3.7L - Service Information - Nitro