Timing Chain Tensioner

Replace the timing chain tensioner on a 2008 Dodge Viper 8.4L V10, requiring partial engine disassembly to access the tensioner located on the front of the engine block.

Warnings

Tools required

Parts

• Timing chain tensioner assembly × 1 — Use OEM Mopar specification
• Timing cover gasket kit × 1 — Use OEM specification
• Tensioner crush washer (if applicable) × 1 — Use OEM specification
• Engine oil × 11 — 0W-40 full synthetic
• Engine coolant × 19 — Mopar HOAT 50/50 premix
• RTV silicone sealant (Mopar specified) × 1 — Use OEM Mopar specification

Fluids

• engine_oil — 11 qt
• coolant — 19 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable and secure away from terminal
3. Allow engine to cool completely (minimum 4 hours if previously run)
4. Remove engine cover by releasing snap fasteners
5. Place drain pans under engine oil drain plug and radiator drain
6. Drain engine oil completely and reinstall drain plug
7. Drain coolant from radiator and engine block drain points
8. Remove front fascia lower splash shields to access lower engine area
9. Support engine using engine support fixture or overhead hoist with load leveler

Procedure

1. 1

   Remove Accessory Drive Components
   Remove the serpentine belt by rotating the tensioner in the direction that relieves tension (verify direction against the belt routing decal or service manual) to release tension. Remove the belt from all pulleys. Mark the routing path if necessary. Remove the alternator mounting bolts and position alternator aside with wiring still connected. Remove the power steering pump mounting bolts and secure pump aside without disconnecting hydraulic lines. Remove the A/C compressor mounting bolts and position compressor aside without disconnecting refrigerant lines.
2. 2

   Remove Water Pump and Thermostat Housing
   Disconnect upper radiator hose from thermostat housing. Remove the thermostat housing bolts and remove housing with thermostat. Remove remaining coolant hoses connected to water pump. Remove the water pump mounting bolts (note different bolt lengths and locations for reassembly). Remove water pump from timing cover and discard gasket.
3. 3

   Remove Harmonic Balancer
   Remove the center bolt from the harmonic balancer using a harmonic balancer holding tool to prevent crankshaft rotation. The bolt is very tight and requires a breaker bar. Once bolt is removed, use a harmonic balancer puller to remove the balancer from the crankshaft snout. Do not hammer on the balancer or use a jaw-type puller that grips the outer ring, as this will damage the assembly.
4. 4

   Remove Timing Cover
   Remove all timing cover bolts (verify exact count and bolt lengths/locations against the service manual for the 8.4L V10). Take photos or label bolt locations for reassembly. Take photos or label bolt locations for reassembly. The cover is sealed with both gasket and RTV sealant. Carefully use a plastic scraper or pry bar at designated pry points to separate the cover from the block. Work slowly around the perimeter to avoid cracking the aluminum cover. Once free, remove the timing cover forward and away from the engine.
5. 5

   Verify Timing Marks
   Before proceeding with tensioner removal, verify that all timing marks are aligned at TDC (Top Dead Center) for cylinder 1. The crankshaft timing mark should align with the mark on the block or chain guide. Both camshaft sprocket timing marks should align with their respective marks on the cylinder heads or timing chain. Take clear photos for reference. Do not rotate the engine once the tensioner is removed.
6. 6

   Release Timing Chain Tension
   Locate the timing chain tensioner on the front of the engine (verify exact location and tensioner type against the service manual for the 8.4L V10). The tensioner applies pressure to the timing chain guide. If equipped with a locking pin access hole, insert a small pin or drill bit through the hole to lock the tensioner in the retracted position before removal. This prevents the tensioner piston from extending during removal.
7. 7

   Remove Timing Chain Tensioner
   Remove the tensioner cap/plug from the tensioner housing if the design uses a serviceable cap. Remove the tensioner housing mounting bolts (verify exact bolt count against the service manual for the 8.4L V10). Note bolt locations for reassembly. Carefully withdraw the tensioner assembly from the engine block. Inspect the mounting bore for debris or damage. If a locking pin was used, remove it from the old tensioner.
   Torque spec

   Tensioner Housing Bolts25 Nm (18 lb-ft)
8. 8

   Inspect Timing Chain and Guides
   With the tensioner removed, visually inspect the timing chain for excessive wear, stretching, or damaged links. Inspect the chain guides (both fixed and tensioned) for wear grooves, cracking, or material loss. Check the tensioner blade or guide that contacts the chain for wear. The chain should not have excessive slack when manually pulled away from the sprockets. If significant wear is present, note that full timing chain replacement is recommended.
9. 9

   Prepare New Tensioner
   Remove the new timing chain tensioner from packaging. Verify the tensioner is in the compressed/locked position. If not, compress the tensioner piston fully and insert a locking pin through the access hole to hold it in place. Prime the tensioner with clean engine oil by filling the oil passage or chamber if accessible. Install a new crush washer on the tensioner cap/plug if the design uses a serviceable cap.
10. 10

    Install New Timing Chain Tensioner
    Clean the tensioner mounting bore in the engine block thoroughly. Apply a thin film of clean engine oil to the tensioner body O-ring or seal. Carefully insert the new tensioner assembly into the engine block, aligning any locating pins or tabs. Install the tensioner housing mounting bolts and tighten to specification in the proper sequence (typically alternating between bolts). If equipped with a serviceable cap, install the tensioner cap/plug with new crush washer and tighten to specification.
    Torque spec

    Tensioner Housing Bolts25 Nm (18 lb-ft)

    Tensioner Cap/Plug30 Nm (22 lb-ft)
11. 11

    Release Tensioner Locking Pin
    Once the tensioner is securely mounted, carefully remove the locking pin from the tensioner. The tensioner piston should extend under spring and hydraulic pressure to apply proper tension to the timing chain guide. Verify the chain guide is properly positioned and the chain has appropriate tension without excessive slack.
12. 12

    Clean and Prepare Timing Cover Sealing Surfaces
    Thoroughly clean all RTV sealant and old gasket material from both the timing cover and engine block sealing surfaces using a plastic scraper. Do not gouge or scratch the aluminum surfaces. Clean with solvent and allow to dry completely. Inspect sealing surfaces for damage, warping, or deep scratches that could cause leaks.
13. 13

    Install Timing Cover
    Install new timing cover gasket according to kit instructions. Apply the Mopar-specified RTV silicone sealant bead (verify bead size and application points against the service manual) to the timing cover sealing surfaces at the block-to-oil pan and block-to-cylinder head junctions. Install the timing cover carefully, ensuring it seats fully against the block without shifting the gasket. Install all timing cover bolts finger-tight first, then tighten to specification in a cross-pattern sequence starting from the center and working outward.
    Torque spec

    Timing Cover Access Bolts12 Nm (9 lb-ft)
14. 14

    Install Harmonic Balancer
    Clean the crankshaft snout and inner bore of the harmonic balancer. Lightly oil the crankshaft snout. Align the balancer keyway with the crankshaft key and slide the balancer onto the snout by hand as far as possible. Install the center bolt and use the harmonic balancer holding tool to prevent rotation. Tighten the center bolt to the factory torque specification (verify exact value and any torque-angle procedure against the service manual for the 8.4L V10 before tightening).
15. 15

    Reinstall Water Pump and Accessories
    Install water pump with new gasket, tightening bolts to specification. Reconnect all coolant hoses to water pump. Install thermostat housing with new gasket and tighten bolts. Install A/C compressor, power steering pump, and alternator with all mounting bolts tightened to specification. Route and install serpentine belt according to routing diagram. Verify belt is properly seated in all pulley grooves.

Reassembly

1. Reinstall engine cover and secure all snap fasteners
2. Reinstall front fascia lower splash shields
3. Refill engine with 11 quarts of 0W-40 full synthetic oil
4. Refill cooling system with 19 quarts of Mopar HOAT 50/50 coolant following proper bleeding procedure
5. Reconnect negative battery cable
6. Start engine and verify proper operation, monitoring for unusual noises from timing chain area
7. Allow engine to reach operating temperature and check for oil or coolant leaks around timing cover
8. Recheck engine oil level after initial run and top off if necessary
9. Clear any diagnostic trouble codes that may have set during repair

Verification

• Listen for proper timing chain operation with no rattling, slapping, or abnormal noises from front of engine at idle and under acceleration
• Verify no oil leaks from timing cover gasket or tensioner mounting area after engine reaches operating temperature
• Verify no coolant leaks from water pump or thermostat housing
• Confirm serpentine belt runs smoothly without vibration or misalignment
• Check engine oil level and coolant level after initial test drive
• Perform road test verifying normal engine performance and no unusual noises under load

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