Crankshaft Main Seal Replacement - Front

Easy step by step repair guide on how to replace an automotive engine crankshaft front seal, though appearances may differ, the process is the same on most vehicles.

Difficulty Scale: 6 of 10

Tools and Supplies Needed

  • Socket set
  • Dampener puller
  • Large pry bar
  • Shop towels
  • Carburetor cleaner
  • Replacement front seal
  • Hammer
  • Seal installation tool or large socket
  • Safety eye wear and gloves
  • Hydraulic jack
  • Jack stands
  • Silicone sealer (high grade)
Begin with the vehicle on level ground, engine "OFF" in park with the emergency brake on. If engine access requires to lift the car, do so safely using jack stands.

Step 1 - Release the serpentine belt tensioner, while removing the belt from the engine compartment.

Removing Serpentine Belt
Step 2
- Once the serpentine belt has been removed, remove the front vibration dampener retainer bolt and washer. In this illustration an air impact is being used, but this can be done be with a regular socket wrench by holding the crankshaft at the flywheel. (Note: The starter will need to be removed.) Visit - Starter replacement

Removing Vibration Dampener Bolt
Step 3 - After the bolt and washer have been removed, assemble a dampener puller with the appropriate mounting bolts. (Note: Puller mounting bolts must be obtained.)

Vibration Dampener Puller
Step 4
- Once puller mounting bolts have been supplied, install the puller. Try to get the puller square with the dampener for proper operation. (Note: If puller is allowed to wonder it can break and cause damage.)

Puller Installed
Step 5 - Next, tighten the puller center screw to start removing the dampener, continue this action until the dampener has released from the crankshaft. If a regular socket wrench is used, the crankshaft will need to be held.

Removing Vibration Dampener
Step 6
- As the dampener becomes loose the puller tool will be attached to the dampener, remove the tool.

Vibration Dampener Removed
Step 7 - Once the dampener has been removed it will expose the failed front crankshaft seal.

Failed Crankshaft Seal
Step 8 - Using a large standard screw driver "pop" the seal loose and out of the timing chain cover or engine block. (Note: Some applications require a seal removal tool, but most of the time an alternative is available.)

Removing Front Crankshaft Oil Seal
Step 9 - Once the seal has been removed inspect the seal for obvious failure. Such failures include: dried, torn or dilapidated.

Crankshaft Seal Removed
Step 10 - After the seal has been removed use a shop towel with carburetor cleaner to wipe down the area and seal mounting surface.

Cleaning Seal Mounting Surface
Step 11 - Next, compare the old seal to the new replacement seal. Then add a small bead of high grade silicone sealer to the outside rim of the seal.

Applying Silicone Sealer to Crankshaft Seal
Step 12 - After the sealer has been applied push the seal into place. (Note: Always install seals with the "lip" of the seal pointing inward.)

Crankshaft Seal Set Into Place
Step 13 - Then, use a large socket or seal installation tool to finish installing the seal. The seal is fully installed when its flush with the timing cover or block.

Installing New Crankshaft Seal
Step 14 - Once the crankshaft seal has been installed, the dampener sealing surface must be prepared for installation.

Dampener Sealing Surface
Step 15 - Use a small piece of emery cloth or sand paper and clean the seal mounting surface.

Cleaning Dampener Seal Surface
Step 16 - Completely clean the sealing surface to enable proper seal operation.

Resurfaced Sealing Area
Step 17 - Then assemble the dampener (balancer) installation tool using the proper thread insert. This will be used to install the dampener.

Vibration Dampener Installation Tool
Step 18 - After the tool is assembled, apply a small amount of grease to the sealing surface. This will help lube the seal during the break-in process.

Apply Grease To Sealing Surface
Step 19 - Now that the balancer is ready to install, align the woodruff key to the dampener key slot.

Aligning Woodruff Key
Step 20 - Once the balancer has been aligned push the balancer into place, ready to fully install the balancer into the crankshaft (press fit.)

Balancer Set Into Place
Step 21 - Next, screw the balancer installation tool into the end of the crankshaft.

Balancer Installation Tool Installed
Step 22 - Once the installer is in place, using wrenches to wind the balancer completely onto the crankshaft. The outside wrench holds the balancer steady. When complete unscrew installation tool to remove.

Wrench Tightens Installation Tool
Step 24 - After the installation is complete, apply silicone sealer to the mounting bolt washer. Then wind the bolt into the end of the crankshaft.

Sealer Installed On Mounting Bolt
Step 25 - After the bolt has been installed, use an air impact or regular socket wrench to tighten. (Note: Bolt needs to be tight, check a repair manual for exact torque specification for a particular vehicle.)

Tighten Balancer Mounting Bolt
Once the balancer has been installed, reinstall serpentine belt and any plastic covers which were removed in the repair process.

Helpful Information

An engine front crankshaft seal is mounted into the front timing cover which rides against the vibration dampener sealing surface. This seal controls oil from leaking to the outside of the engine, once the seal starts leaking it must be replaced. A harmonic balancer or dampener is the common term for a weighted unit used to help an engine run smoothly.

Best Practices

  • Always use top quality seals to avoid premature failure.
  • Clean sealing surfaces to enhance sealing ability.
  • Use high quality silicone sealer
Article first published