DRIVE GP-FINAL 4504254 - Caterpillar

Projection of the Piston
Determining the Piston Projection
It is important to ensure the correct projection of the piston so the piston does not contact the cylinder head and valves. The correct projection of the piston also ensures the efficient combustion of fuel which is necessary in order to conform to requirements for emissions and engine performance.
Illustration 14 g01253773
Measuring the piston projection (43) Tool for measuring projectionUse the following procedure to measure the protrusion of each piston above the cylinder block during assembly of the engine. Ensure that the correct parts are being used and inspect the parts for damage or wear if the projection of the piston above the top face of the cylinder block is not within the tolerance that is provided in Table 11 and Table 12. If the tolerance is not within the specifications the piston and the piston pin bearing must be replaced.
Determine the top center position of the piston with a dial indicator assembly.Note: Reference Testing and Adjusting, SENR5546, "3064 and 3066 Engines for Caterpillar Built Machines" for determining the top center position of the piston.
Install the dial indicator assembly on the top of the block. Set the needle of the dial indicator to zero.
Measure the projection of the piston (43) at three places on the top of the piston. Take an average of the three measurements in order to determine the piston projection. Subtract the projection from the installed thickness of the cylinder head gasket in order to determine the clearance between the top of the piston and the cylinder head. Reference Table 11 and reference Table 12If any of the following components are replaced or remachined, the projection of the piston above the top face of the cylinder block must be measured.
Block
Crankshaft
Cylinder head
Connecting rod
Piston pin bearing
PistonNote: The top of the piston should not be machined. Note: If the original piston is installed, be sure that the original piston is assembled to the correct connecting rod and installed in the original cylinder.
Table 11
Piston Projection
3066 and 3064 Engines    
All Engines    
0.55 to 1.15 mm (0.022 to 0.050 inch)    
Compressed Thickness of the Cylinder Head Gasket    
1.70 0.10 mm (0.067 0.004 inch)    
Table 12
Piston Projection
3046 and 3044 Engines    
Naturally Aspirated Engines    
- 0.25 to 0.15 mm (- 0.010 to 0.006 inch)    
Turbocharged Engines    
0.05 to 0.45 mm (0.002 to 0.018 inch)    
Compressed Thickness of the Cylinder Head Gasket    
1.20 0.05 mm (0.047 0.002 inch)    Connecting Rod Length For 3066 and 3064 Engines
Reference Testing and Adjusting, SENR5546, "3064 and 3066 Engines for Caterpillar Built Machines" for additional information on the length of grade for a connecting rod.Storage
Proper protection of the piston from corrosion is very important. Corrosion will start in as little as one hour after the piston has been cleaned. When the piston will not be inspected for one hour or less the