Engines: Engine Rebuilding: Engine disassembly
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Topic IntroductionHelp

Remove centerbolt & flywheel

Summary
The objective of this procedure is to show you how to remove the centerbolt and flywheel and mount the engine in a stand. Start with the centerbolt remembering to use only high tensile grade bolts.

Part 1. Preparation and safety

Objective

Remove the centrebolt and flywheel and mount the engine in a stand

Personal safety

Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:

If you are not certain what is appropriate or required, ask your supervisor.

Safety check

Points to note


Part 2: Step-by-step instruction

  1. Support the engine
    Most engine stands make it difficult to get to the flywheel or flexplate area at the back of the block, so it may be best not to put the engine onto an engine stand before you complete this task. Use a set of dolly wheels instead, or sit the block on the ground supported at three points.
  2. Remove the centerbolt
    The centerbolt is a good place to start. The flywheel or flexplate is connected directly to the rear of the crankshaft. The harmonic balancer and main pulley are connected to the front of the crankshaft. The centerbolt holds the balancer and pulley in place. All of these components spin together as one piece.
    The centerbolt is usually tightened to a very high torque setting, so you need to stop the crank from moving while you apply pressure to loosen it. Insert a large flathead screwdriver between two of the teeth of the flexplate or flywheel. One of the alignment dowels in the back of the block will keep the crank from spinning as you loosen the centerbolt with a breaker bar or a large1/2 inch drive ratchet wrench. Using the same screwdriver technique to hold the plate still, use a big wrench and loosen the bolts that connect the flywheel or flexplate to the crank.
  3. Organize and label small parts
    Every fastener, every small component that is removed from the engine must go into some type of labeled container. You can use self-sealing ziplock food bags, or takeaway containers, or a multi-bin organizer, but the important thing is that you label everything carefully. Do not skip this important step. A successful rebuild will depend on the accurate identification of dozens of different sized fasteners.
  4. Mount the engine on a stand
    Once the flexplate or flywheel is off, the rest of the task of disassembly will be easier if the engine is on a stand. Remember that the entire motor will be supported by the bolts that connect the block to the stand, so it is essential only to use high tensile grade bolts – US grade 8, or metric Class10.9
    If you have to move the engine somewhere else to finish disassembly, check that your engine stand is not too wide to fit though a standard size door, in which case use dolly wheels or an engine cradle to reposition it first . Then you can hoist the engine to a stand and clear the dolly wheels or block support out of the way.