Dodge Durango (HB). Manual - part 1039

OPERATION

Oil from the oil pan is pumped by a gerotor type oil pump directly mounted to the crankshaft nose. Oil pressure is
controlled by a relief valve mounted inside the oil pump housing.

1 - OIL FLOW TO RIGHT CYLINDER HEAD

7 - OIL FLOW TO COUNTER BALANCE SHAFT

2 - CYLINDER BLOCK MAIN OIL GALLERY

8 - OIL PUMP OUTLET TO CYLINDER BLOCK

3 - LEFT CYLINDER HEAD OIL GALLERY

9 - OIL PUMP

4 - OIL FLOW TO BOTH SECONDARY TENSIONERS

10 - OIL FLOW TO CRANKSHAFT MAIN JOURNALS

5 - OIL FLOW TO LEFT CYLINDER HEAD

11 - CRANKSHAFT MAIN BEARING JOURNALS

6 - OIL PRESSURE SENSOR LOCATION

12 - RIGHT CYLINDER HEAD OIL GALLERY

ENGINE - 3.7L SERVICE INFORMATION

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The camshaft exhaust valve lobes and rocker arms are lubricated through a small hole in the rocker arm; oil flows
through the lash adjuster then through the rocker arm and onto the camshaft lobe. Due to the orientation of the
rocker arm, the camshaft intake lobes are not lubed in the same manner as the exhaust lobes. The intake lobes are
lubed through internal passages in the camshaft. Oil flows through a bore in the No. 3 camshaft bearing bore, and
as the camshaft turns, a hole in the camshaft aligns with the hole in the camshaft bore allowing engine oil to enter
the camshaft tube. The oil then exits through 1.6mm (0.063 in.) holes drilled into the intake lobes, lubricating the
lobes and the rocker arms.

Engine Lubrication Flow Chart - Block: Table 1

FROM

Oil Pickup Tube

Oil Pump

Oil Filter

Block Main Oil Gallery

1. Crankshaft Main Journal

2. Left Cylinder Head*

3. Right Cylinder Head*

4. Counterbalance Shaft Rear Journal

Crankshaft Main Journals

Crankshaft Rod Journals

Crankshaft Number One Main Journal

1. Front Timing Chain Idler Shaft

2. Counterbalance Shaft - Front Journal

3. Both Secondary Chain Tensioners

Left Cylinder Head

Refer to Engine Lubrication Flow Chart - Cylinder
Heads: Table 2

Right Cylinder Head

Refer to Engine Lubrication Flow Chart - Cylinder
Heads: Table 2

* The cylinder head gaskets have an oil restricter to control oil flow to the cylinder heads

Engine Lubrication Flow Chart - Cylinder Heads: Table 2

FROM

Cylinder Head Oil Port (in bolt hole)

Diagonal Cross Drilling to Main Oil Gallery

Main Oil Gallery (drilled through head from rear to front)

1. Base of Camshaft Towers

2. Lash Adjuster Towers

Base of Camshaft Towers

Vertical Drilling Through Tower to Camshaft Bearings**

Lash Adjuster Towers

Diagonal Drillings to Hydraulic Lash Adjuster Pockets

** The number three camshaft bearing journal feeds oil into the hollow camshaft tubes. Oil is routed to the intake
lobes, which have oil passages drilled into them to lubricate the rocker arms.

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ENGINE - 3.7L SERVICE INFORMATION

DIAGNOSIS AND TESTING

ENGINE OIL LEAK

Begin with a thorough visual inspection of the engine, particularly at the area of the suspected leak. If an oil leak
source is not readily identifiable, the following steps should be followed:

1. Do not clean or degrease the engine at this time because some solvents may cause rubber to swell, temporarily

stopping the leak.

2. Add an oil soluble dye (use as recommended by manufacturer). Start the engine and let idle for approximately 15

minutes. Check the oil dipstick to make sure the dye is thoroughly mixed as indicated with a bright yellow color
under a black light.

3. Using a black light, inspect the entire engine for fluorescent dye, particularly at the suspected area of oil leak. If

the oil leak is found and identified, repair per service manual instructions.

4. If dye is not observed, drive the vehicle at various speeds for approximately 24 km (15 miles), and repeat inspec-

tion.If the oil leak source is not positively identified at this time, proceed with the air leak detection test method.

Air Leak Detection Test Method

1. Disconnect the breather cap to air cleaner hose at the breather cap end. Cap or plug breather cap nipple.

2. Remove the PCV valve from the cylinder head cover. Cap or plug the PCV valve grommet.

3. Attach an air hose with pressure gauge and regulator to the dipstick tube.

CAUTION: Do not subject the engine assembly to more than 20.6 kPa (3 PSI) of test pressure.

4. Gradually apply air pressure from 1 psi to 2.5 psi maximum while applying soapy water at the suspected source.

Adjust the regulator to the suitable test pressure that provide the best bubbles which will pinpoint the leak
source. If the oil leak is detected and identified, repair per service manual procedures.

5. If the leakage occurs at the rear oil seal area, refer to the section, Inspection for Rear Seal Area Leak.

6. If no leaks are detected, turn off the air supply and remove the air hose and all plugs and caps. Install the PCV

valve and breather cap hose.

7. Clean the oil off the suspect oil leak area using a suitable solvent. Drive the vehicle at various speeds approx-

imately 24 km (15 miles). Inspect the engine for signs of an oil leak by using a black light.

INSPECTION FOR REAR SEAL AREA LEAKS

Since it is sometimes difficult to determine the source of an oil leak in the rear seal area of the engine, a more
involved inspection is necessary. The following steps should be followed to help pinpoint the source of the leak.

If the leakage occurs at the crankshaft rear oil seal area:

1. Disconnect the battery.

2. Raise the vehicle.

3. Remove torque converter or clutch housing cover and inspect rear of block for evidence of oil. Use a black light

to check for the oil leak:

a. Circular spray pattern generally indicates seal leakage or crankshaft damage.

b. Where leakage tends to run straight down, possible causes are a porous block, distributor seal, camshaft

bore cup plugs oil galley pipe plugs, oil filter runoff, and main bearing cap to cylinder block mating surfaces.

4. If no leaks are detected, pressurize the crankcase as outlined in the, Inspection (Engine oil Leaks in general)

CAUTION: Do not exceed 20.6 kPa (3 psi).

5. If the leak is not detected, very slowly turn the crankshaft and watch for leakage. If a leak is detected between

the crankshaft and seal while slowly turning the crankshaft, it is possible the crankshaft seal surface is damaged.
The seal area on the crankshaft could have minor nicks or scratches that can be polished out with emery cloth.

CAUTION: Use extreme caution when crankshaft polishing is necessary to remove minor nicks and
scratches. The crankshaft seal flange is especially machined to complement the function of the rear oil seal.

6. For bubbles that remain steady with shaft rotation, no further inspection can be done until disassembled.

ENGINE - 3.7L SERVICE INFORMATION

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CHECKING ENGINE OIL PRESSURE

1. Remove oil pressure sending unit (2) and install

gauge assembly C-3292.

2. Run engine until thermostat opens.

3. Oil Pressure:

•

Curb Idle - 25 kPa (4 psi) minimum

•

3000 rpm - 170 - 758 kPa (25 - 110 psi)

4. If oil pressure is 0 at idle, shut off engine. Check

for a clogged oil pick-up screen or a pressure relief
valve stuck open.

REAR SEAL AREA LEAKS

If the leakage occurs at the crankshaft rear oil seal area:

1. Disconnect the battery.

2. Raise the vehicle.

3. Remove torque converter or clutch housing cover and inspect rear of block for evidence of oil. Use a black light

to check for the oil leak:

a. Circular spray pattern generally indicates seal leakage or crankshaft damage.

b. Where leakage tends to run straight down, possible causes are a porous block, camshaft bore cup plugs, oil

galley pipe plugs, oil filter runoff, and main bearing cap to cylinder block mating surfaces. See Engine, for
proper repair procedures of these items.

4. If no leaks are detected, pressurized the crankcase as outlined in the section, Inspection (Engine oil Leaks in

general)

CAUTION: Do not exceed 20.6 kPa (3 psi).

5. If the leak is not detected, very slowly turn the crankshaft and watch for leakage. If a leak is detected between

CAUTION: Use extreme caution when crankshaft polishing is necessary to remove minor nicks or
scratches. The crankshaft seal flange is specially machined to complement the function of the rear oil seal.

6. For bubbles that remain steady with shaft rotation, no further inspection can be done until disassembled. (Refer

to 9 - ENGINE - DIAGNOSIS AND TESTING) , under the Oil Leak, for components inspections on possible
causes and corrections.

7. After the oil leak root cause and appropriate corrective action have been identified, (Refer to 9 - ENGINE/EN-

GINE BLOCK/CRANKSHAFT OIL SEAL - REAR - REMOVAL).

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ENGINE - 3.7L SERVICE INFORMATION

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