3.7L Engine - Service Information: Other RAM Pickup 2500

MECHANICAL

CYLINDER COMPRESSION PRESSURE LEAKAGE

Note. The results of a cylinder compression pressure test can be utilized to diagnose several engine malfunctions.

Note. Ensure the battery is completely charged and the engine starter motor is in good operating condition. Otherwise the indicated compression pressures may not be valid for diagnosis purposes.

1. Clean the spark plug recesses with compressed air.
2. Remove the spark plugs and record the cylinder number of each spark plug for future reference.
3. Inspect the spark plug electrodes for abnormal firing indicators such as fouled, hot, oily, etc.
4. Disable the fuel system and perform the fuel system pressure release procedure. Refer to «FUEL DELIVERY, GAS»(ref-457834-S33436164992012030200000) .
5. Insert a compression pressure gauge and rotate the engine with the engine starter motor for three revolutions.
6. Record the compression pressure on the 3rd revolution. Continue the test for the remaining cylinders. NOTE: The recommended compression pressures are to be used only as a guide to diagnosing engine problems. An engine should not be disassembled to determine the cause of low compression unless some malfunction is present.
7. Compression should not be less than 689 kPa (100 psi) and not vary more than 25 percent from cylinder to cylinder.
8. If one or more cylinders have abnormally low compression pressures, repeat the compression test. NOTE: If the same cylinder or cylinders repeat an abnormally low reading on the second compression test, it could indicate the existence of a problem in the cylinder in question.
9. If one or more cylinders continue to have abnormally low compression pressures, perform the cylinder combustion pressure leakage test. Refer to «CYLINDER COMBUSTION PRESSURE LEAKAGE»(ref-457795-S24923936492012030200000) .

CYLINDER COMBUSTION PRESSURE LEAKAGE

The combustion pressure leakage test provides an accurate means for determining engine condition.

Combustion pressure leakage testing will detect

1. Exhaust and intake valve leaks (improper seating).
2. Leaks between adjacent cylinders or into water jacket.
3. Any causes for combustion/compression pressure loss.

1. Check the coolant level and fill as required. DO NOT install the radiator cap.
2. Start and operate the engine until it attains normal operating temperature, then turn the engine OFF.
3. Remove the spark plugs.
4. Remove the oil filler cap.
5. Remove the air cleaner hose.
6. Calibrate the tester according to the manufacturer's instructions. The shop air source for testing should maintain 483 kPa (70 psi) minimum, 1,379 kPa (200 psi) maximum and 552 kPa (80 psi) recommended.
7. Perform the test procedures on each cylinder according to the tester manufacturer's instructions. Set piston of cylinder to be tested at TDC compression. While testing, listen for pressurized air escaping through the throttle body, tailpipe and oil filler cap opening. Check for bubbles in the radiator coolant.

All gauge pressure indications should be equal, with no more than 25% leakage.

FOR EXAMPLE: At 552 kPa (80 psi) input pressure, a minimum of 414 kPa (60 psi) should be maintained in the cylinder.

Refer to CYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHART .

CYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHART

TOP 19 REASONS THAT MAY LEAD TO ENGINE OIL CONSUMPTION

1. Tapered and Out-of-Round Cylinders The increased piston clearances permit the pistons to rock in the worn cylinders. While tilted momentarily, an abnormally large volume of oil is permitted to enter on one side of the piston. The rings, also tilted in the cylinder, permit oil to enter on one side. Upon reversal of the piston on each stroke, some of this oil is passed into the combustion chamber.
2. Distorted Cylinders This may be caused by unequal heat distribution or unequal tightening of cylinder head bolts. This condition presents a surface which the rings may not be able to follow completely. In this case, there may be areas where the rings will not remove all of the excess oil. When combustion takes place, this oil will be burned and cause high oil consumption.
3. Improper operation of "PCV" system The main purpose of the Positive Crankcase Ventilation (PCV) valve is to recirculate blow-by gases back from the crankcase area through the engine to consume unburned hydrocarbons. The PCV system usually has a one way check valve and a make up air source. The system uses rubber hoses that route crankcase blow by gases to the intake manifold. Vacuum within the engine intake manifold pulls the blow by gases out of the crankcase into the combustion chamber along with the regular intake air and fuel mixture. The PCV system can become clogged with sludge and varnish deposits and trap blow by gases in the crankcase. This degrades the oil, promoting additional formation of deposit material. If left uncorrected, the result is plugged oil rings, oil consumption, rapid ring wear due to sludge buildup, ruptured gaskets and seals due to crankcase pressurization.
4. Worn Piston Ring Grooves For piston rings to form a good seal, the sides of the ring grooves must be true and flat - not flared or shouldered. Piston rings in tapered or irregular grooves will not seal properly and, consequently, oil will pass around behind the rings into the combustion chamber.
5. Worn, Broken or Stuck Piston Rings When piston rings are broken, worn or stuck to such an extent that the correct tension and clearances are not maintained, this will allow oil to be drawn into the combustion chamber on the intake stroke and hot gases of combustion to be blown down the cylinder past the piston on the power stroke. All of these conditions will result in burning and carbon build up of the oil on the cylinders, pistons and rings.
6. Cracked or Broken Ring Lands Cracked or broken ring lands prevent the rings from seating completely on their sides and cause oil pumping. This condition will lead to serious damage to the cylinders as well as complete destruction of the pistons and rings. Cracked or broken ring lands cannot be corrected by any means other than piston replacement.
7. Worn Valve Stems and Guides When wear has taken place on valve stems and valve guides, the vacuum in the intake manifold will draw oil and oil vapor between the intake valve stems and guides into the intake manifold and then into the cylinder where it will be burned.
8. Bent or Misaligned Connecting Rods Bent or misaligned connecting rods will not allow the pistons to ride straight in the cylinders. This will prevent the pistons and rings from forming a proper seal with the cylinder walls and promote oil consumption. In addition, it is possible that a bearing in a bent connect rod will not have uniform clearance on the connecting rod wrist pin. Under these conditions, the bearing will wear rapidly and throw off an excessive amount of oil into the cylinder.
9. Fuel Dilution If raw fuel is allowed to enter the lubrication system, the oil will become thinner and more volatile and will result in higher oil consumption. The following conditions will lead to higher oil consumption; Excess fuel can enter and mix with the oil via a leaking fuel injector Gasoline contaminated with diesel fuel Restricted air intake Excessive idling
10. Contaminated Cooling Systems Corrosion, rust, scale, sediment or other formations in the water jacket and radiator will prevent a cooling system from extracting heat efficiently. This is likely to cause cylinder distortion thus leading to higher oil consumption.
11. Oil Viscosity The use of oil with a viscosity that is too light may result in high oil consumption. Refer to the vehicle owners™ manual for the proper oil viscosity to be used under specific driving conditions and/or ambient temperatures.
12. Dirty Engine Oil Failure to change the oil and filter at proper intervals may cause the oil to be so dirty that it will promote accumulation of sludge and varnish and restrict oil passages in the piston rings and pistons. This will increase oil consumption; dirty oil by nature is also consumed at a higher rate than clean oil.
13. Crankcase Overfull Due to an error in inserting the oil dip stick so that it does not come to a seat on its shoulder, a low reading may be obtained. Additional oil may be added to make the reading appear normal with the stick in this incorrect position which will actually make the oil level too high. If the oil level is so high that the lower ends of the connecting rods touch the oil in the oil pan excessive quantities of oil will be thrown on the cylinder walls and some of it will work its way up into the combustion chamber.
14. Excessively High Oil Pressure A faulty oil pressure relief valve may cause the oil pressure to be too high. The result will be that the engine will be flooded with an abnormally large amount of oil in a manner similar to that which occurs with worn bearings. This condition may also cause the oil filter to burst.
15. Aftermarket Performance Chips and Modification Increasing performance through the use of performance/power enhancement products to a stock or factory engine will increase the chance of excessive oil consumption.
16. Lugging Engine Lugging is running the engine at a lower RPM in a condition where a higher RPM (more power/torque) should be implemented. Especially susceptible on vehicles equipped with a manual transmission. This driving habit causes more stress loading on the piston and can lead to increases in engine oil consumption.
17. Turbocharged Engines There is a possibility for PCV "push" due to higher crankcase pressure (as compared to naturally aspirated engines) which is normal for turbocharged engines. This condition causes varying amounts of engine oil to enter the intake manifold, charge air cooler and associated plumbing to and from the charge air cooler, also a leaking turbocharger seal will draw oil into the combustion chamber where it will burn (blue smoke from tail pipe may be present) and form carbon deposits which contribute to further oil consumption as they interfere with proper engine function.
18. Restricted Air Intake Excessive restriction in the air intake system will increase engine vacuum and can increase oil consumption, an extremely dirty air filter would be one example of this situation.
19. Intake Manifold port seals Engines that have a "V" configuration and a "wet valley" could draw oil into the intake ports due to improper sealing between the intake manifold ports and cylinder head. Causes may include improper torque of intake manifold bolts, corrosion (aluminum intake manifold) and or warped sealing surface.

Scheme 126

Due to the high amounts of failures cased by dust, dirt, moisture and other foreign debris being introduced to the engine during service. Covers or caps are needed to reduce the possible damage that can be caused or created.

Scheme 127

Covers over openings will reduce any possibilities for foreign materials to enter the engine systems. Using miller tool (special tool #10368, Set, Universal Protective Cap), Select the appropriated cover needed to the procedure.

REPAIR DAMAGED OR WORN THREADS

Damaged or worn threads can be repaired. Essentially, this repair consists of

1. Drilling out worn or damaged threads.
2. Tapping the hole with a special Heli-Coil Tap, or equivalent.
3. Installing an insert into the tapped hole to bring the hole back to its original thread size.

FORM-IN-PLACE GASKETS AND SEALERS

There are numerous places where form-in-place gaskets are used on the engine. Care must be taken when applying form-in-place gaskets to assure obtaining the desired results. Do not use form-in-place gasket material unless specified. Bead size, continuity, and location are of great importance. Too thin a bead can result in leakage while too much can result in spill-over which can break off and obstruct fluid feed lines. A continuous bead of the proper width is essential to obtain a leak-free gasket.

There are numerous types of form-in-place gasket materials that are used in the engine area. Mopar® Engine RTV GEN II, Mopar® ATF-RTV, and Mopar® Gasket Maker gasket materials, each have different properties and can not be used in place of the other.

MOPAR® ENGINE RTV GEN II

Mopar® Engine RTV GEN II is used to seal components exposed to engine oil. This material is a specially designed black silicone rubber RTV that retains adhesion and sealing properties when exposed to engine oil. Moisture in the air causes the material to cure. This material is available in three ounce tubes and has a shelf life of one year. After one year this material will not properly cure. Always inspect the package for the expiration date before use.

MOPAR® ATF RTV

Mopar® ATF RTV is a specifically designed black silicone rubber RTV that retains adhesion and sealing properties to seal components exposed to automatic transmission fluid, engine coolants, and moisture. This material is available in three ounce tubes and has a shelf life of one year. After one year this material will not properly cure. Always inspect the package for the expiration date before use.

MOPAR® GASKET MAKER

Mopar® Gasket Maker is an anaerobic type gasket material. The material cures in the absence of air when squeezed between two metallic surfaces. It will not cure if left in the uncovered tube. The anaerobic material is for use between two machined surfaces. Do not use on flexible metal flanges.

MOPAR® GASKET SEALANT

Mopar® Gasket Sealant is a slow drying, permanently soft sealer. This material is recommended for sealing threaded fittings and gaskets against leakage of oil and coolant. Can be used on threaded and machined parts under all temperatures. This material is used on engines with multi-layer steel (MLS) cylinder head gaskets. This material also will prevent corrosion. Mopar® Gasket Sealant is available in a 13 oz. aerosol can or 4oz./16 oz. can w/applicator.

COOLING SYSTEM TESTER METHOD

Install Cooling System Tester (special tool #7700, Tester, Cooling System) or equivalent to pressure cap neck. Start the engine and observe the tester's pressure gauge. If gauge pulsates with every power stroke of a cylinder a combustion pressure leak is evident.

CLEANING

Thoroughly clean the oil pan and engine block gasket surfaces.

Use compressed air to clean out

1. The galley at the oil filter adaptor hole.
2. The front and rear oil galley holes.
3. The feed holes for the crankshaft main bearings.

Once the block has been completely cleaned, apply Loctite PST pipe sealant with Teflon 592 to the threads of the front and rear oil galley plugs. Tighten the 1/4 inch NPT plugs to 20 N.m (177 in. lbs.) torque. Tighten the 3/8 inch NPT plugs to 27 N.m (240 in. lbs.) torque.

Scheme 128

Scheme 129

1. Wipe the main bearing inserts (1,2) clean.
2. Inspect the inserts for abnormal wear patterns, scoring, grooving, fatigue, pitting and for metal or other foreign material imbedded in the lining.
3. Inspect the back of the inserts for fractures, scrapes or irregular wear patterns.
4. Inspect the insert locking tabs for damage.
5. Inspect the crankshaft thrust washers for scoring, scratches, wear or blueing.
6. Replace any bearing that shows abnormal wear.
7. Inspect the main bearing bores for signs of scoring, nicks and burrs.
8. If the cylinder block main bearing bores show damage, replace the engine block.
9. Use Cylinder Indicator (special tool #C-119, Cylinder Indicator) (2) to correctly measure the inside diameter of the cylinder bore (3). A cylinder bore gauge capable of reading in 0.003 mm (0.0001 in.) Increments is required. If a bore gauge is not available, do not use an inside micrometer.
10. Measure the inside diameter of the cylinder bore at three levels below the top of the bore (4). Start at the top of the bore, perpendicular (across or at 90°) to the axis of the crankshaft at point A (1).
11. Repeat the measurement near the middle of the bore then repeat the measurement near the bottom of the bore.
12. Determine the taper by subtracting the smaller diameter from the larger diameter.
13. Rotate the measuring device 90° to point B (1) and repeat the three measurements. Verify that the maximum taper is within specifications.
14. Determine out-of-roundness by comparing the difference between each measurement.
15. If the cylinder bore taper does not exceed 0.025 mm (0.001 inch) and out-of-roundness does not exceed 0.015 mm (0.0006 inch) then the cylinder bore can be honed. If the cylinder bore taper or out- of-round condition exceeds the maximum limits, replace the cylinder block.

Note. A slight amount of taper always exists in the cylinder bore after the engine has been in use for a period of time.

Scheme 130

The main bearings are "select fit" to achieve proper oil clearances. For main bearing selection, the crankshaft position sensor target wheel (2) has grade identification marks stamped into it. These marks are read from left to right, corresponding with journal number 1, 2, 3, 4. The crankshaft position sensor target wheel is mounted to the number 6 counter weight (1) on the crankshaft.

MAIN BEARING JOURNAL DIAMETER (CRANKSHAFT REMOVED)

Remove the crankshaft from the cylinder block. Refer to CRANKSHAFT , Removal , 3.7L .

Clean the oil off the main bearing journal.

Determine the maximum diameter of the journal with a micrometer. Measure at two locations 90° apart at each end of the journal.

The maximum allowable taper is 0.008mm (0.0004 inch.) and maximum out of round is 0.005mm (0.002 inch). Compare the measured diameter with the journal diameter specification (Main Bearing Fitting Chart). Select inserts required to obtain the specified bearing-to-journal clearance.

Install the crankshaft into the cylinder block. Refer to INSPECTION .

Check crankshaft end play.

CRANKSHAFT MAIN BEARING SELECTION

1. Service main bearings are available in four grades. The chart identifies the four service grades available.

1. Using a suitable cleaning solvent clean the pistons in warm water and towel dry.
2. Use a wood or plastic scraper to clean the ring land grooves.

2WD

1. Disconnect the negative cable from the battery. CAUTION: Remove the viscous fan before raising engine. Failure to do so may cause damage to the fan blade, fan clutch and fan shroud.
2. Remove the cooling fan.
3. Raise the vehicle.
4. Remove the engine oil filter.
5. Remove the oil drain trough.
6. Support the engine with a suitable jack and a block of wood across the full width of the engine oil pan.
7. Support the front axle with a suitable jack.
8. Remove the (4) bolts that attach the engine mounts to the front axle.
9. Remove the (3) bolts that attach the front axle to the left engine bracket.
10. Lower the front axle.
11. Remove the through bolts
12. Raise the engine far enough to be able to remove the left and right engine mounts.
13. Remove the (8) mount to engine attaching bolts
14. Remove the engine mounts.

Scheme 131

Scheme 132

Scheme 133

1. Disconnect the negative cable from the battery. CAUTION: Remove the viscous fan before raising engine. Failure to do so may cause damage to the fan blade, fan clutch and fan shroud.
2. Remove the cooling fan.
3. Raise the vehicle.
4. Remove the skid plate.
5. Remove the front crossmember.
6. Remove the engine oil filter.
7. Remove the oil drain trough.
8. Support the engine with a suitable jack and a block of wood across the full width of the engine oil pan.
9. Support the front axle with a suitable jack.
10. Remove the 4 bolts that attach the engine mounts to the front axle.
11. Remove the 3 bolts that attach the front axle to the left engine bracket.
12. Lower the front axle.
13. Remove the 6 through bolts
14. Raise the engine far enough to be able to remove the left (4) and right (8) engine mounts.
15. Remove the mounts. 1 - BOLT 2 - ENGINE MOUNT SUPPORT BRACKET 3 - BOLT 1 - BOLT 2 - ENGINE MOUNT SUPPORT BRACKET
16. Remove the engine mount brackets (2).

Note. For mount to engine block and left engine bracket to front axle bolts, apply Mopar® Lock and Seal Adhesive, Medium Strength Threadlocker.

1. Install the right and left side engine mounts to the engine block with (8) bolts. Torque bolts to 54 N.m (40 ft. lbs.).
2. Insert the (2) through bolts into the right and left side engine mounts and loose assemble the two nuts onto the through bolts.
3. Lower the engine until the through bolts rest onto the slots in the frame brackets.
4. Tighten the through bolt nuts to 94 N.m (70 ft. lbs.).
5. Install the oil drain trough.
6. Install the engine oil filter.
7. Lower the vehicle.
8. Install the cooling fan.
9. Reconnect the negative battery cable.

4WD

Note. For mount to engine block and left engine bracket to front axle bolts, apply Mopar® Lock and Seal Adhesive, Medium Strength Threadlocker.

1. Install the right and left side engine mounts (4, 8)to the front axle. Torque nuts to 94 N.m (70 ft. lbs.).
2. Raise the front axle into the frame and install the left and right side through bolts. Torque nuts to 94 N.m (70 ft. lbs.).
3. Insert the two upper through bolts into the right and left side engine mounts and loose assemble the two nuts onto the through bolts.
4. Lower the engine until the left and right side engine brackets rest on the through bolts, and the lower engine bracket through holes align with the engine mounts, and the left engine bracket holes align with the front axle slots.
5. Loose assemble the 3 bolts that attach the front axle to the left engine bracket.
6. Loose assemble the lower through bolts.
7. Torque the nuts for the 4 through bolts to 101 N.m (75 ft. lbs.).
8. Torque the 3 bolts that attach the front axle to the left engine bracket to 101 N.m (75 ft. lbs.).
9. Install the oil drain trough.
10. Install the engine oil filter.
11. Install the front crossmember.
12. Install the skid plate.
13. Lower the vehicle.
14. Install the cooling fan.
15. Reconnect the negative battery cable.

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 information instructions.
4. If dye is not observed, drive the vehicle at various speeds for approximately 24 km (15 miles), and repeat inspection. If the oil leak source is not positively identified at this time, proceed with the AIR LEAK DETECTION TEST METHOD.

ENGINE OIL CHANGE

Change engine oil at mileage and time intervals described in Maintenance Schedules.

Run engine until achieving normal operating temperature.

1. Position the vehicle on a level surface and turn engine off.
2. Hoist and support vehicle on safety stands.
3. Remove oil fill cap.
4. Place a suitable drain pan under crankcase drain.
5. Remove drain plug from crankcase and allow oil to drain into pan. Inspect drain plug threads for stretching or other damage. Replace drain plug if damaged.
6. Install drain plug in crankcase.
7. Lower vehicle and fill crankcase with specified type and amount of engine oil.
8. Install oil fill cap.
9. Start engine and inspect for leaks.
10. Stop engine and inspect oil level.

Note. Care should be exercised when disposing used engine oil after it has been drained from a vehicle engine. Refer to the WARNING at beginning of this section.

Scheme 134

The engine oil pan (1) is made of laminated steel and has a single plane sealing surface. see scheme 126 The sandwich style oil pan gasket has an integrated windage tray (2) and steel carrier. The sealing area of the gasket is molded with rubber and is designed to be reused as long as the gasket is not cut, torn or ripped.

Scheme 135

1. Disconnect the negative battery cable.
2. Install engine support fixture special tool (special tool #8534B, Fixture, Driveline Support). Do not raise engine at this time.
3. Loosen both left and right side engine mount through bolts. Do not remove bolts.
4. Remove the structural dust cover, if equipped.
5. Drain engine oil.
6. Disconnect transmission fluid cooler lines at radiator, transmission fittings and clips. NOTE: When disconnecting the transmission oil cooler lines, it is necessary to replace the line clip that is located on the oil pan stud. The retention force of the clip is severely degraded upon removal.
7. Remove the front crossmember. Refer to «CROSSMEMBER, Lower Control Arm , Removal»(ref-457829-S02998048772012030200000) or «CROSSMEMBER, Transmission , Removal»(ref-457829-S13491836922012030200000) . CAUTION: Only raise the engine enough to provide clearance for oil pan removal. Check for proper clearance at fan shroud to fan and cowl to intake manifold.
8. Raise engine using special tool (special tool #8534B, Fixture, Driveline Support) to provide clearance to remove oil pan.
9. Remove the oil pan mounting bolts (1 -17) and oil pan. 1 - OIL PAN 2 - WINDAGE TRAY AND INTEGRATED OIL PAN GASKET NOTE: Do not pry on oil pan (1) or oil pan gasket (2). Gasket is integral to engine windage tray and does not come out with oil pan.
10. Unbolt oil pump pickup tube and remove tube.
11. Inspect the integral windage tray and gasket (2) and replace as needed.

1. Clean oil pan in solvent and wipe dry with a clean cloth.
2. Clean the oil pan gasket surface. DO NOT use a grinder wheel or other abrasive tool to clean sealing surface.
3. Clean oil screen and tube thoroughly in clean solvent.

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. CAUTION: Over tightening heat shield fasteners, may cause shield to distort and/or crack.
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: Over tightening heat shield fasteners, may cause shield to distort and/or crack.
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.)

Scheme 136

The intake manifold is made of a composite material and features 300 mm (11.811 in.) long runners which maximizes low end torque. see scheme 145

Scheme 137

The intake manifold uses single plane sealing which consist of six individual press in place port gaskets (2) to prevent leaks. The throttle body attaches directly to the intake manifold.

TIMING VERIFICATION

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

Note. The blue link plates on the chains and the dots on the camshaft drive sprockets may not line up during the timing verification procedure. The blue link plates are lined up with the sprocket dots only when re-timing the complete timing drive. Once the timing drive is rotated blue link-to-dot alignment is no longer valid.

Engine base timing can be verified by the following procedure

Scheme 138

1. Remove the cylinder head covers (See appropriate cylinder head cover removal procedure).
2. Using a mirror, locate the TDC arrow on the front cover. Rotate the crankshaft until the mark on the crankshaft damper (2) is aligned with the TDC arrow on the front cover (2). The engine is now at TDC.
3. Note the location of the V6 mark stamped into the camshaft drive gears (1,2). If the V6 mark on each camshaft drive gear is at the twelve o'clock position, the engine is at TDC on the exhaust stroke. If the V6 mark on each gear is at the six o'clock position, the engine is at TDC on the compression stroke.
4. If both of the camshaft drive gears are off in the same or opposite directions, the primary chain or both secondary chains are at fault. See «CHAIN and SPROCKETS, Timing»(ref-457795-S07281382772012030200000) procedure.
5. If only one of the camshaft drive gears is off and the other is correct, the problem is confined to one secondary chain. See «TIMING - SINGLE CAMSHAFT»(ref-457795-S39027052622012030200000) .
6. If both camshaft drive gear V6 marks are at the twelve o'clock or the six o'clock position the engine base timing is correct. Reinstall the cylinder head covers.

Scheme 139

1. Ensure that the engine is at TDC with both camshaft sprocket V6 marks in the 12 o'clock position.
2. Look down the left cylinder head chain cavity. The timing dot (2) on the counter balance shaft drive gear should be in the 6 o'clock position.

Scheme 140

Note. To adjust the timing on one camshaft, perform the following procedure.

Scheme 141

1. Using the Wedge Locking Tool (special tool #8379, Locking Tool, Wedge) (2), stabilize the secondary chain drive. For reference purposes, mark the chain-to-sprocket position.
2. Remove the camshaft drive gear retaining bolt (3).
3. Carefully remove the camshaft drive gear from the camshaft.
4. Re-index the camshaft drive gear in the chain until the V6 mark is at the same position as the V6 mark on the opposite camshaft drive gear (1,2).
5. Using the Camshaft Holder (special tool #8428A, Holder, Camshaft), rotate the camshaft until the alignment dowel on the camshaft is aligned with the slot in the camshaft drive gear. CAUTION: Remove excess oil from camshaft sprocket retaining bolt before reinstalling bolt. Failure to do so may cause over-torqueing of bolt resulting in bolt failure.
6. Position the camshaft drive gear onto the camshaft, remove oil from bolt then install the retaining bolt. Using Special Tools, Spanner Wrench (special tool #6958, Wrench, Spanner) with Adapter Pins (special tool #8346, Pins, Adapter) and a suitable torque wrench, tighten the retaining bolt to 122 N.m (90 ft. lbs.)
7. Remove the Wedge Locking Tool (special tool #8379, Locking Tool, Wedge).
8. Rotate the crankshaft two full revolutions, then verify that the camshaft drive gear V6 marks are in fact aligned.
9. Install the cylinder head covers. Refer to «COVER(S), Cylinder Head , Installation , 3.7L»(ref-457795-S18626148182012030200000) for left head cover and «COVER(S), Cylinder Head , Installation , 3.7L»(ref-457795-S10268980662012030200000) for right head cover.

Scheme 142

Scheme 143

Scheme 144

Scheme 145

Scheme 146

1. Disconnect the negative battery cable.
2. Drain the cooling system. Refer to «Standard Procedure»(ref-457792-S30781673372012030200000).
3. Remove right and left cylinder head covers. Refer to «COVER(S), Cylinder Head, Removal, 3.7L»(ref-457795-S38087059622012030200000) for left head cover and «COVER(S), Cylinder Head, Removal, 3.7L»(ref-457795-S11243807712012030200000) for right head cover.
4. Remove the radiator fan shroud. Refer to «FAN, Cooling, Electric, Removal»(ref-457792-S13033663812012030200000) and «FAN, Cooling, Viscous, Removal»(ref-457792-S41329399382012030200000).
5. Rotate engine until the timing mark on crankshaft damper (2) aligns with TDC mark on timing chain cover (2) and the camshaft sprocket "V6" marks are at the 12 o'clock position (No. 1 TDC exhaust stroke). see scheme 164and see scheme 165. 1 - RIGHT CYLINDER HEAD ACCESS PLUG 2 - LEFT CYLINDER HEAD ACCESS PLUG
6. Remove the power steering pump. Refer to «Pump, Removal»(ref-457772-S19330296352012030200000).
7. Remove the access plugs from the left (2) and right (1) cylinder heads for access to the chain guide fasteners. see scheme 166
8. Remove the oil fill housing to gain access to the right side tensioner arm fastener.
9. Remove crankshaft damper and the timing chain cover. Refer to «DAMPER, Vibration, Removal, 3.7L»(ref-457795-S21288300202012030200000). Refer to «COVER(S), Engine Timing, Removal, 3.7L»(ref-457795-S00384933232012030200000). 1 - PRIMARY CHAIN TENSIONER 2 - ADJUSTABLE PLIERS 3 - SPECIAL TOOL 8514
10. Collapse and pin primary chain tensioner (1). CAUTION: Plate behind left secondary chain tensioner could fall into oil pan. Therefore, cover pan opening.
11. Remove secondary chain tensioners. 1 - CYLINDER HEAD 2 - CAMSHAFT POSITION SENSOR 3 - BOLT
12. Remove camshaft position sensor bolt (3) and remove sensor (2). see scheme 168 1 - Camshaft hole 2 - Special Tool 8428A CAUTION: Care should be taken not to damage the camshaft target wheel. Do not hold the target wheel while loosening or tightening the camshaft sprocket. Do not place the target wheel near a magnetic source of any kind. A damaged or magnetized target wheel could cause a vehicle no start condition. CAUTION: Do not forcefully rotate the camshafts or crankshaft independently of each other. Damaging intake valve to piston contact will occur. Ensure the negative battery cable is disconnected and isolated to guard against accidental starter engagement.
13. Remove left and right camshaft sprocket bolts.
14. While holding the left camshaft steel tube with Camshaft Holder (special tool #8428A, Holder, Camshaft) (2), remove the left camshaft sprocket. Slowly rotate the camshaft approximately 15 degrees clockwise to a neutral position.
15. While holding the right camshaft steel tube with Camshaft Holder (special tool #8428A, Holder, Camshaft) (2), remove the left camshaft sprocket. Slowly rotate the camshaft approximately 45 degrees counterclockwise to a neutral position.
16. Remove idler sprocket assembly bolt.
17. Slide the idler sprocket assembly and crank sprocket forward simultaneously to remove the primary and secondary chains.
18. Remove both pivoting tensioner arms and chain guides.
19. Remove primary chain tensioner.