Part 1. Preparation and safety
Objective
- Remove the crankshaft and bearings.
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:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection - such as rubber gloves and barrier cream
- Respiratory equipment - such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
Safety check
- Some engine parts are very heavy get assistance to lift heavy or awkward parts like the crankshaft.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- You may need to set the engine block on the floor to remove the crankshaft.
- Make sure all the parts are placed in their correct order into an organizer tray.
- Examine the crankshaft and bearings for possible cause of engine failure.
Part 2: Step-by-step instruction
- Remove the crankshaft bearing caps
You may need some additional leverage to loosen the bolts holding the crankshaft caps. Some blocks have just two bolts per cap. This block has four bolts on each of the caps on the center three main journals. The cap may not come away easily, especially if it has long alignment dowels. Make sure the bolts aren't still threaded in, hold them up halfway out of their holes and tap lightly on the side of the bolt heads, first one side then the other until the cap is clear to be removed. The lower half of the main crank bearings will be inside the caps, and should come away with the caps as you remove them.
- Remove the crankshaft
Remove the adaptor and main seal now. If you cannot get it past the engine stand adaptor, then set the block on the floor to remove the crankshaft.
Crankshafts are both heavy and awkwardly shaped, so be very careful lifting it out of the block, or get someone else to help you.
- Remove the bearings
Make sure none of the parts of the main bearings are stuck to the journals of the crankshaft. The rest of them will remain in the block. Now that the block is upside down, these are the upper halves of the bearings, the ones with the oil fed holes in them.
Push each half a bearing to the side from the center with you fingers. If necessary, use a screwdriver to help push, but be careful not to scratch the bearing if it might be reusable. One of the bearings will be larger, with sides to it. That's the thrust bearing. Remove this by using a small pick or flat head screwdriver in the alignment slot.
- Examine the bearings for reusability
Main bearings, like rod bearings, can also overheat and break loose. These bearings show a heavy amount of fine metal shavings embedded in the soft metal of the wearing surface. Some of this is due to normal engine wear, but most is probably residue from the broken rod bearing, some of which may still be around in places like the oil passages behind the bearing.
When there are visible wear patterns on the bearings, especially if the copper core is showing through in some areas, then they will not be reusable and should be replaced. If you are not sure of their reusability, take them to a machine shop specialist for advice.
If the engine has a rope seal, or a two piece rear main seal, pull out the two other halves.
