Dodge Nitro. Manual — part 128

The oil lubrication system is a full-flow filtration, pressure feed type. The oil pump body is mounted to the
engine block. The pump inner rotor is driven by the crankshaft. A windage tray, increases power by minimizing
oil windage at high engine RPM. For increased oil cooling, an oil pan mounted, oil-to-coolant oil cooler is used.
See Fig. 238.

OPERATION

ENGINE LUBRICATION SYSTEM

Fig. 239: Oil Lubrication System
Courtesy of CHRYSLER LLC

Engine oil stored in the oil pan (5) is drawn in and discharged by a gear rotor type oil pump (2, 3). The oil pump

LEFT HEAD

1 - CRANKSHAFT

9 - PEDESTAL DRILLED PASSAGE

2 - OUTER ROTOR

10 - EXHAUST ROCKER SHAFT

3 - INNER ROTOR

11 - SHAFT/PEDESTAL DOWEL PASSAGE

4 - RELIEF VALVE

12 - CAMSHAFT BEARING BORE

5 - OIL PAN

13 - CYLINDER BLOCK OIL GALLERY

6 - OIL SCREEN

14 - CYLINDER HEAD GASKET

7 - OIL PUMP CASE

15 - HEAD BOLT HOLE

8 - OIL FLOWS TO ONLY ONE PEDESTAL ON
EACH HEAD - SECOND FROM REAR ON
RIGHT HEAD - SECOND FROM FRONT ON
LEFT HEAD

16 - INTAKE ROCKER SHAFT

2007 Dodge Nitro R/T

2007 ENGINE 4.0L - Service Information - Nitro

is directly coupled to the crankshaft (1). Oil pressure is regulated by a relief valve (4). The oil is fed through an
oil filter and to the crankshaft journals from the oil gallery (8) in the cylinder block. This gallery also feeds oil
under pressure to the cylinder heads. Oil flows through each cylinder heads oil passage to the rocker shafts (10,
16). Oil then feeds the camshaft journals (12), rocker arms, and hydraulic lash adjusters. See Fig. 239.

DIAGNOSIS AND TESTING

CHECKING ENGINE OIL PRESSURE

Check oil pressure using a gauge at oil pressure switch location.

1. Remove the oil pressure switch (1) (Refer to REMOVAL ).

2. Install oil pressure test gauge, C-3292 with Adapter 8406. For Special Tool identification, (Refer to

SPECIAL TOOLS ).

3. Warm engine to normal operating temperature.

4. Monitor gauge readings at idle and 3000 RPM. For specifications (Refer to SPECIFICATIONS ).

OIL

DESCRIPTION

ENGINE OIL

For engine oil type and capacity. Refer to DESCRIPTION .

STANDARD PROCEDURE

OIL LEVEL CHECK

CAUTION: If oil pressure is 0 at idle, Do Not Run engine at 3000 RPM.

2007 Dodge Nitro R/T

2007 ENGINE 4.0L - Service Information - Nitro

Fig. 240: 4.0L ENGINE
Courtesy of CHRYSLER LLC

The best time to check engine oil level is after the engine has sat overnight, or if the engine has been running,
allow the engine to be shut off for at least 5 minutes before checking oil level.

Checking the oil while the vehicle is on level ground will improve the accuracy of the oil level reading. Add oil
only when the level is at, or below, the ADD mark on the indicator.

ENGINE OIL AND FILTER CHANGE

Change engine oil at mileage and time intervals described in the Maintenance Schedule. Refer to
DESCRIPTION .

TO CHANGE ENGINE OIL

WARNING:

NEW OR USED ENGINE OIL CAN BE IRRITATING TO THE SKIN. AVOID
PROLONGED OR REPEATED SKIN CONTACT WITH ENGINE OIL.
CONTAMINANTS IN USED ENGINE OIL, CAUSED BY INTERNAL
COMBUSTION, CAN BE HAZARDOUS TO YOUR HEALTH. THOROUGHLY
WASH EXPOSED SKIN WITH SOAP AND WATER. DO NOT WASH SKIN
WITH GASOLINE, DIESEL FUEL, THINNER, OR SOLVENTS, HEALTH
PROBLEMS CAN RESULT. DO NOT POLLUTE, DISPOSE OF USED
ENGINE OIL PROPERLY. CONTACT YOUR DEALER OR GOVERNMENT
AGENCY FOR LOCATION OF COLLECTION CENTER IN YOUR AREA.

2007 Dodge Nitro R/T

2007 ENGINE 4.0L - Service Information - Nitro

Fig. 241: 4.0L ENGINE
Courtesy of CHRYSLER LLC

1. Run engine until achieving normal operating temperature.

2. Position the vehicle on a level surface and turn engine off.

3. Open hood, remove engine oil fill cap. See Fig. 241.

Fig. 242: Engine Oil Cooler, Coolant Hose, Filter & Lower Radiator Hose
Courtesy of CHRYSLER LLC

4. Raise vehicle on hoist.

5. Place a suitable drain pan under crankcase drain.

2007 Dodge Nitro R/T

2007 ENGINE 4.0L - Service Information - Nitro