Engines: Engine Rebuilding: Engine final assembly
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Topic IntroductionHelp

Install crankshaft

Summary
The objective of this procedure is to show you how to install the crankshaft. The first step is to clean the block, bearings and crankshaft in preparation for the installation.

Part 1. Preparation and safety

Objective

Install the crankshaft

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. Clean and prepare
    Clean the saddles of the block, and do the same to both sides of all the bearings to make sure there's no dust or build up from the previous lubricant. Clean the crankshaft itself as well.
  2. Install bearings
    Install the main bearings and double check that the oil holes line up with the ones in the block. At the same time, clean the caps and wipe and install the bearings for them as well.
    When the motor starts up for the first time and while it's running, the crankshaft requires more lubrication than the camshaft. Engine assembly lubricant is better for the camshaft journals and lobes because it is specifically designed to provide the start up and break-in protection that high quality bearings deserve. Make sure you wipe some on the faces of the thrust bearing as well.
  3. Install two-piece main seal
    If the engine has a two-piece main seal, Install the upper half before lowering the crankshaft into place. On a neoprene rubber seal, the pointy lip must point towards the inside of the motor. When you press it into place use the plastic protector shim between the seal and the block to keep the rubber back of the seal from being damaged by the sharp edge of the block. For engines with an older type of rope seal, work the rope into the groove of the block and then use a large socket to tap it deeper into the groove. Cut off the excess flush with the block using a razor knife, or just clip it off with some cutting pliers. You can bolt the cap in upside down for some motors to install the rope seal in the rear cap. in either case, put a little oil or assembly lube on the lip or the rope so the seal won't burn out on start-up.
    For all types of engines it's very important to put a dab of silicon sealer on each side of the seal where the rear cap meets the metal of the block. If you don't do this, oil will leak from the rear of the block because there is no gasket here. Spread a little on the tips of neoprene or rope seals as well.
  4. Install crankshaft and caps
    Be gentle as you lay the crankshaft in place. Then, lubricate each of the caps and put them in place. Each bolt that goes into the engine needs to have some type of lubricant on it's threads. The main cap bolts should have some engine oil on the threads to reach the proper torque setting. Make sure the bolts are threaded in a few turns then tap on the caps to seat them.
    If you have rubber rear main seals, remember to use the protector shim on the seal when you put it in the rear main cap, and of course, rubber or rope seals get a bit of oil on the seal itself. The contact surfaces of the cap needs to be clean to seal correctly against the silicone on the block. Before the main cap bolts can be torqued, they should also have some oil put on the cap where the head of the bolt is going to contact it.
    Make sure you have all the torque specifications for your engine readily available. You should be able to find what you need in the correct repair manual.
    Carry out the final torquing of the main caps in three increments. Whatever the torque specification, tighten the bolts first to one third that amount, then two thirds, then again to final specification. If you have four bolt main caps, do the inner bolts first.
    Leave the cap that has the thrust bearing in it to last. When the other caps are correctly tightened, hit the back of the crank with a rubber mallet or hammer on another hammer to line up and seat the thrust bearings. Now go through the three increments to torque the cap with the thrust bearings, inner bolts first if it's a four bolt cap.
  5. Install one-piece main seal
    For a one piece rear main seal, you need access to the rear of the block. This type of engine uses an adaptor that bolts to the block. This way the rear main seal is fitted in after the adaptor is sealed and bolted in place.
    To install the seal, you will probably have to take the block out of the stand so that you have access to the rear area of the block, then lift the engine back onto the stand after installing the seal. You may be able to install the adaptor while it is on the block if you can get it past the engine stand adaptor. Alternatively, you can leave the main seal and install it later.