3584091 Volvo.Penta Support

Length of a Connecting Rod
CRL is the connecting rod length. The length of the connecting rod is given in Table 1 for each length grade of connecting rod.In order to ensure that the piston height above the cylinder block is correct, six length grades of connecting rods are used in production. The length grade is identified by a letter or a color which is marked on the side of the connecting rod. The longest grade is marked with the letter "A". The shortest grade is marked with the letter "F". The difference in each length grade is 0.03 mm (0.001 inch).The length grade of a connecting rod is determined in the factory by machining an eccentric hole in a semi-finished piston pin bushing.If the connecting rod must be replaced, a new connecting rod assembly must be purchased and installed. The length grade of the new connecting rod must be specified. The new connecting rod contains a new piston pin bearing. The piston pin bearing is reamed to the correct bore. Refer to Table 1.Replace Only the Piston or the Bearing for the Piston Pin
This procedure is applicable when the original connecting rod is used with the following components: piston and piston pin bearing.
Remove the bearing for the piston pin, which was installed in the factory, from the connecting rod. Install a new bushing in the connecting rod. If necessary, ream the new bearing in order to obtain the correct clearance between the piston pin and the bearing.Refer to Specifications, "Piston and Rings" for dimensions of bearings and piston pins.
Install a new piston, if necessary. The new piston will be the "Std" height grade. Also, a new piston pin may be required.Refer to Specifications, "Piston and Rings" for specifications of pistons and piston rings.
Measure the height of the piston above the cylinder block in order to ensure the correct piston height.If the height of the piston is incorrect, a new connecting rod must be installed. If the piston height is too high, a shorter connecting rod is required. If the piston height is too low, a longer connecting rod is required. Refer to Table 1.Replacing the Connecting Rod and Piston
This procedure determines the length of the connecting rod. The length of the connecting rod must be known so that the correct length of a replacement for the connecting rod can be purchased.Determine the length grade of the connecting rod by one of the following characteristics:
Length grade letter
Measuring the lengthIf the letter for the length grade is used in order to determine the length grade, refer to Table 1. If the length of the connecting rod must be measured in order to determine the length grade, refer to Illustration 1.
Table 1
Length grades of the connecting rod    
Length grade that is used in Production    Length Grade that is used for Replacement    Length Of The Connecting Rod (CRL)    
"A" and "B"    "B"    
132.05 to 132.08 mm (5.199 to 5.200 inch)    
"C" and "D"     "D"    
131.99 to 132.02 mm (5.196 to 5.198 inch)    
"E" and "F"     "F"    
131.93 to 131.96 mm (5.194 to 5.195 inch)    If the mark for the length grade cannot be observed on the connecting rod, perform the following procedure in order to measure the length of the connecting rod ("CRL").
Illustration 1 g00396379
(1) Measuring pins (2) Connecting rod
Use the following tools that are provided by the customer in order to measure the distances for the connecting rod (2) which are specified in Illustration 1:
Appropriate gauges for measuring distance
Measuring pins (1)
Ensure that the measuring pins (1) are parallel. If the measuring pins are not parallel, refer to "Distortion of a Connecting Rod". This will determine if the distortion is within the tolerance.Measure "CRL". Compare the "CRL" that is measured to the "CRL" that is given in Table 1. The length grade of the connecting rod is determined by this "CRL".Distortion of a Connecting Rod
Illustration 2 g00720855
(A) 127 mm (5.0 inch) (B) The allowable tolerance for parallelism between center lines is 0.25 mm ( 0.010 inch). (1) Measuring pins (2) Connecting rod
Use the following tools that are provided by the customer in order to measure the distances for the connecting rod (2) which are specified in Illustration 2:
Appropriate gauges for measuring distance
Measuring pins (1)
Measure the connecting rod for distortion between the bores.The bores for the crankshaft bearing and the bearing for the piston pin must be square and parallel with each other within the required limits. When the bearings for the connecting rod are removed, the limits for parallelism and for squareness are 0.25 mm (0.010 inch) . The limits are measured at a distance of 127 mm (5.0 inch) (A) from each side of the connecting rod.Inspect the Bearing and Piston Pin for Wear
Note: The bolts on the connecting rod are installed in the connecting rod by a special process. The bolts should not be rotated or removed. If the bolts are rotated or removed, the connecting rod and the bolts will be damaged.
Inspect the bearing for the piston pin and the piston pin for wear.
Measure the clearance of the piston pin in the bearing for the piston pin. Refer to Specifications, "Connecting Rod" for dimensions.If the bearing or the piston pin are not within tolerances, the component must be replaced. If the clearance between the bearing and piston pin is not within the tolerance, one or both components must be replaced.