0338632 JOHNSON COVER, Thermostat

Start By:a. remove piston cooling jetsb. remove oil pan 1. Use tool (A) to turn the engine flywheel to move counterweights (2) in position for the removal of the main bearing caps. If necessary, the counterweights can be removed.2. Remove the four bolts, and remove bearing caps (1) from the crankshaft. 3. Remove lower bearing halves (3) from bearing caps (1). 4. Remove thrust plates (4) from each side of the center main bearing.
If the crankshaft is turned in the wrong direction, the tab of the bearing will be pushed between the crankshaft and cylinder block. This can cause damage to either or both.
5. Install tool (B) in the oil hole in the crankshaft journal, and remove upper main bearing halves (5) as the crankshaft is turned and the bearing is moved out of the cylinder block. On the center main journal that has no oil hole, put a thin piece of soft material that will not damage the crankshaft journal against the end of the bearing, opposite the tab. Hit the bearing with the soft material until the tab of the bearing is free from the cylinder block. Remove the upper half of the main bearing.Install Crankshaft Main Bearings
Make sure the upper and lower halves of bearings are installed so the bearing tabs fit into the notch in cylinder block and bearing caps.
Install the main bearings dry when the clearance checks are made. Put clean engine oil on the main bearings for final assembly. 1. Install tool (B) in the oil hole of the crankshaft. Put the upper bearing half (with oil hole) in position on the crankshaft. Use tool (A) to turn the engine flywheel and push the bearing half in position with tool (B). 2. Put clean engine oil on thrust plates (1), and install the plates on each side of the center main bearing. 3. Make sure bearing caps (2) are clean, and install lower bearing halves (3) in the caps.The serviceman must be very careful to use Plastigage, tool (D) correctly. The following points must be remembered:... Make sure that the backs of the bearings and the bores are clean and dry.... Make sure that the bearing locking tabs are properly seated in their slots.... The crankshaft must be free of oil where the Plastigage touches it.... If the main bearing clearances are checked with the engine upright or on its side, the crankshaft will have to be lifted up with a force equal to the weight of the crankshaft and held against the crown of the bearing. If the crankshaft is not supported, the weight of the crankshaft will cause incorrect readings.... Put a piece of Plastigage on the crown of the bearing half that is in the cap. Do not allow the Plastigage to extend over the edge of the bearing. ... Install the bearing cap using the correct torque-turn specifications. Do not use an impact wrench. Be careful not to dislodge the bearing when the cap is installed.... Do not turn the crankshaft with the Plastigage installed.... Carefully remove the cap but do not remove the Plastigage. Measure the width of the Plastigage while it is in the bearing cap or on the crankshaft journal. Do this by using the correct scale on the package. Record the measurements.... Remove the Plastigage before reinstalling the cap.When using Plastigage, the readings can sometimes be unclear. For example, all parts of the Plastigage are not the same width. Measure the major widths to make sure that they are within the specification range. Also, experience has shown that when checking clearances tighter than 0.10 mm (.004 in) the readings may be low by 0.013 to 0.025 mm (.0005 to .0010 in). Out-of-round journals can give faulty readings. Also, journal taper may be indicated when one end of the Plastigage is wider that the other.For complete details concerning measuring bearing clearances, see Engine Bearings And Crankshafts, Form No. SEBD0531. 4. Check the bearing clearances with Plastigage (D) as follows:a. Put a piece of the Plastigage on the surface of the lower bearing half.b. Install main bearing caps (2) with the word "FRONT" and the cast part number toward the front of the cylinder block. Each cap has a number on the bottom surface and must be installed in the same position as the correct number on the right side of the block pan rail.c. Put Fel-Pro C100 Lubricant on the main bearing cap bolts, and hand tighten in number sequence to a torque of 190 14 N m (140 10 lb ft). Then hand tighten the bolts in the number sequence shown 180 5° more.d. Remove the caps and measure the Plastigage. The main bearing clearance must be 0.122 to 0.241 mm (.0048 to .0095 in).5. Put the bearing caps in position, and tighten the bolts as in Step 4. An impact wrench can be used for the final 180 5° torque tightening turn.
Each counterweight has a number, and must be installed in the same position as the correct number on the crankshaft mounting pad to prevent damage to the crankshaft when the engine is run.
6. Make sure the dowels are in position, and install counterweights (8) on the crankshaft as follows:a. Lubricate bolt threads, shank and bolt seat with 334-0519 Grease before assembly.b. Tighten bolts in counterweights 1 and 8 to 200 5 N m (150 4 lb ft).c. Loosen bolts in counterweights 1 and 8.d. Tighten bolts in all counterweights to 70 5 N m (37 4 lb ft).e. Turn bolts in all counterweights an additional 120° 5°. 7. Check the crankshaft end play with tooling (C). The end play is controlled by the thrust plates on the center main bearing. End play with new bearings is 0.17 to 0.63 mm (.007 to .025 in.).End By:a. install piston cooling jetsb. install oil pan