Identify the procedures to install the crankshaft.
The crankshaft is the first component installed, but before reassembling the engine, you must perform certain preassembly procedures.
6101. Preassembly
To ensure proper lubrication of moving parts, all bearings, shafts, and contact surfaces must be lubricated before installation and engine oil should be used for this.
Never reuse old gaskets and seals. Once a seal has been removed, it is damaged and damaged seals can be a source of leakage that results in premature wear and damage to moving parts.
During assembly of the engine, almost every nut and bolt to be tightened has a specific torque.
These torque specifications are listed in the TM and must be strictly adhered to. Over-tightened bolts and nuts will result in excess stress on the metal, and under-tightened nuts and bolts will result in oil or vacuum and pressure leaks.
Basically, all engines are assembled in the same manner. This study unit provides a basic knowledge of assembly, and your TM will provide you with details of the particular engine you will be rebuilding or repairing.
6102. Installing the Crankshaft
The crankshaft is the first component that must be installed if the engine is to be assembled in a logical order. This may vary depending on the type of engine you are rebuilding. Before actually placing the crankshaft in the engine, position the engine block with the crankshaft side up. Install the rear main bearing seals (the rear main bearing is the only main bearing with seals). These seals are installed in grooves provided to the rear of the point from which the rear main journal of the crankshaft rests in the engine and on the groove provided in the rear main bearing cap. There are various types of seals (felt packing, neoprene, encased, etc.). Figure 6-1 and 6-2 show to
common types of rear seals.
Fig 6-1. Encased seal
Fig 6-2. Two-piece seal
The encased seal is installed after the crankshaft has been installed in the engine. Care must be exercised to ensure that the seal is driven into the block evenly, or damage may result.
To install the crankshaft, first install the upper halves of the crankshaft's main bearings in the engine block, and the lower halves in the main bearing caps (fig 6-3). Make sure the bearing halves are thoroughly cleaned and, as mentioned previously, all friction surfaces coated with engine oil.
The bearing tangs must fit into the slots in the cap and block evenly, or they will be flattened. The tang is provided to prevent the bearing from turning with the crankshaft. If a bearing turns, it will cause almost immediate damage.
Fig 6-3. Installing main bearing halves.
With all bearings in place, lower the crankshaft into the block carefully so that no parts are damaged. Though not always necessary, it is usually best to install the woodruff key and crankshaft timing gear before installing the crankshaft in the block.
To hold the crankshaft in place, you must install all the bearing caps. First, install the front main bearing cap. Place the front main bearing in its position. Some manufacturers recommend lubricating the threads of the bearing cap bolts before installation and torqueing.
Tighten the bearing cap bolts until the caps fit snugly. Once this has been done, center the crankshaft thrust bearings and tighten them according to manufacturer's recommendations.
Consult the specific TM for the engine in question. Remember, when tightening components to torque specifications, do NOT apply full torque immediately.
With a torque wrench, tighten one side to five or ten pound-feet, then tighten the other side equally. Switch back to the first bolt and repeat the procedure until both bolts are tightened to manufacturer's specifications.
When the bearings are installed, the crankshaft must be checked for end play just as you did before removing the crankshaft during disassembly. With this done and with problems corrected by installing another crankshaft thrust bearing if necessary, the crankshaft installation is now completed and you can install the camshaft and tappets.
Lesson 1 Exercise: Complete items 1 through 4 by performing the actions required. Check your responses with those provided at the end of the lesson.
1. Before crankshaft installation, all bearings, shafts and contact surfaces must be ________________________________________________________________ . 2. Old gaskets and seals are not reused in engine repair. Why not?
________________________________________________________________
3. When installing the crankshaft, tighten bearings to specifications in accordance with ________________________________________________________________.
4. To install the crankshaft, first
a. install the upper halves of the main bearings in the engine block b. install the lower haves of the main bearing in the engine block c. tighten the bearing cap bolts until the caps fit snugly
d. center the crankshaft thrust bearings and tighten them Lesson 1 Exercise Solutions
Reference
1. Lubricated with engine oil 6101
2. Old gaskets are damaged and can be a source of leakage 6101
3. the specific TM 6102
4. a. 6102
Lesson Summary. In this lesson you learned the preassembly procedures and the importance of lubricating before installation. You also learned how to install the crankshaft and associated bearings and seals. Let's continue the engine's assembly with the installation of the camshaft.
Lesson 2. CAMSHAFT INSTALLATION