0303278 JOHNSON SUPPORT,Armature plate

Problem 1.
Too Much VibrationProbable Cause
Loose bolt or nut holding pulley or damper Tighten bolt or nut.
Pulley, or damper has a defect Install a new pulley or damper.
Engine supports are loose, worn, or have a defect Tighten all mounting bolts. Install new components if necessary.
Misfiring or running rough Refer to Step 2.
Fan blade not in balance Loosen or remove fan belts and operate engine for a short time at the rpm where the vibration was present. If vibration is not still present, replace the fan assembly.Problem 2.
Loud Noise (Clicking) From Valve CompartmentProbable Cause
Broken valve springs or locks Install new parts where necessary. Broken locks can cause the valve to slide into the cylinder and cause much damage.
Loose bolts holding rocker arm assembly Tighten the bolts to the proper torque
Too much valve clearance Adjust the valve clearance. Refer to Testing and Adjusting, "Air Inlet And Exhaust System, Cylinder Head, Valve Clearance Setting".
Not enough lubrication Check lubrication in valve compartment. There must be a strong flow of oil at engine high rpm, but only a small flow of oil at low rpm. Oil passages must be clean, especially those sending oil to the cylinder head.Problem 3.
Mechanical Noise (Knock) In EngineProbable Cause
Failure of bearing for connecting rod Inspect the bearing for the connecting rod and the bearing surface on the crankshaft. Install new parts where necessary.
Damage to crankshaft Replace the crankshaft
Defect in attachment Repair or install new components.Problem 4.
Loud Noise From Valve Or Valve Drive ComponentsProbable Cause
Broken valve springs Make replacement of parts with damage.
Broken camshaft Replace the damaged parts. Clean the engine thoroughly.
Broken timing advance gear Replace the timing advance unit.
Damage to valve lifter Clean engine thoroughly. Replace the camshaft and valve lifters. Look for valves that do not move freely. Adjust the valve clearance. Refer to Testing and Adjusting, "Air Inlet And Exhaust System, Cylinder Head, Valve Clearance Setting".
Damage to valves Replace the valves and adjust the valves to the correct clearance.Problem 5.
Little Movement of Rocker Arm and Too Much Valve clearanceProbable Cause
Not enough lubrication Check lubrication in valve compartment. There must be a strong flow of oil at high engine rpm, but only a small flow at low rpm. Oil passages must be clean, especially those sending oil to the cylinder head.
Rocker arm parts worn If there is too much wear, install new parts or rocker arms. Adjust the valve clearance. Refer to Testing and Adjusting, "Air Inlet And Exhaust System, Cylinder Head, Valve Clearance Setting".
End of valve stem worn If there is too much wear, install new valves. Adjust the valve clearance.
Excessive valve clearance Adjust the valve clearance.
Worn push rods If there is too much wear, install new push rods and adjust the valve clearance.
Cam followers worn If there is too much wear, install new cam followers and adjust the valve clearance.
Worn cams on camshaft Check valve lash. Check for free movement of valves or bent valve stems. Install new components as necessary. Adjust the valve clearance.
Loose bolts holding rocker arm assembly Tighten the bolts to the proper torque.Problem 6.
Valve Rotocoil Or Spring Lock Is FreeProbable Cause
Broken locks Broken locks can cause the valve to slide into the cylinder, causing much damage.
Broken valve springs Install new valve springs.Problem 7.
Little or No Valve ClearanceProbable Cause
Worn valve seat or face of valve Reconditioning of cylinder head is needed. Adjust the valve clearance. Refer to Testing and Adjusting, "Air Inlet And Exhaust System, Cylinder Head, Valve Clearance Setting"Problem 8.
Engine Has Early WearProbable Cause
Worn valve seat or face of valve
Dirt in lubrication oil Remove dirty lubrication oil. Install a new oil filter element. Put clean oil in the engine.
Air inlet leaks Inspect all gaskets and connections. Repair all leaks.
Fuel leakage into lubrication oil This leakage will cause high fuel consumption and low engine oil pressure. Repair all leaks. Install new parts where neededPiston Rings
Steel Pistons
Refer to Reuse And Salvage Guidelines , SEBF8059, "Inspection Procedures and Specifications for Pistons", "Procedure for Measurement and Inspection of Pistons"
Illustration 1 g03078402For 3408 engines that have steel pistons with a top ring groove that is a keystone type, use the 325-8423 Piston Ring Groove Gauge (1) to check the top ring groove only. This gauge uses a simple Go/No-Go design. If the piston passes through gauge, the piston cannot be reused.No piston ring groove gauge is available to measure the intermediate piston ring groove and the oil control ring groove on this piston.Connecting Rods And Pistons
Use the 7M-3978 Ring Expander to remove piston rings or install piston rings.Use the 5P-3526 Piston Ring Compressor to install pistons into the cylinder block.Tighten the connecting rod bolts in the step sequence that follows: Procedure for Measurement and Inspection of Pistons
Put engine oil on bolt threads before assembly.
Tighten all bolts to 82 8 N m (60 6 lb ft)
Put a "mark" on each nut and end of bolt.
Tighten each nut 120 5 degrees from the "mark". Connecting Rod Bearings
The connecting rod bearings fit tightly in the bore in the rod. If the bearing joints are fretted, check the bore size. The bore size can be an indication of wear because of a loose fit.Connecting rod bearings are available with 0.63 mm (0.025 inch) and 1.27 mm (0.050 inch) smaller inside diameter than the original size bearing. These bearings are for crankshafts that have been ground.Main Bearings
Three types of main bearings can be used.
Undersized main bearings are available. These bearings are used on a crankshaft that is ground smaller than the original size of crankshaft. The undersized main bearing has a 0.63 mm or 1.27 mm (0.025 inch or 0.050 inch) smaller inside diameter than the original size bearing.
Oversized main bearings are available. These bearings are available with a larger outside diameter than the original size bearings. These bearings are for the cylinder blocks that have had the main bearing bored larger than the original bore