Procedures
NOTE: The connecting rods, caps and bearing shells must be retained in sets, and in the correct sequence. Remove the piston rings over the crown of the piston. If the same piston is to be refitted, mark it relative to its connecting rod to ensure that the original assembly is maintained.
Land Rover Piston Pin Tool:
1. Withdraw the piston pin, using Land Rover tool 18G1150 as follows:
a. Clamp the hexagon body of 18G1150 in a vice.
b. Position the large nut flush with the end of the center screw.
c. Push the screw forward until the nut contacts the thrust race.
d. Locate the piston adaptor 18G1150E with its long spigot inside the bore of the hexagon body.
e. Fit the remover/replacer bush of 18G1150 on the center screw with the flanged end away from the piston pin.
f. Screw the stop-nut about half-way onto the smaller threaded end of the center screw, leaving a gap A of 3 mm (1/8 in) between this nut and the remover/replacer bush.
g. Lock the stop-nut securely with the lock screw.
h. Check that the remover/replacer bush is correctly positioned in the bore of the piston.
i. Push the connecting-rod to the right to expose the end of the piston pin, which must be located in the end of the adaptor d.
j. Screw the large nut up to the thrust race.
k. Hold the lock screw and turn the large nut until the piston pin has been withdrawn from the piston. Dismantle the tool.
2. Remove the carbon deposits from pistons, particularly from the ring grooves. Examine the pistons for signs of damage or excessive wear. Fit new pistons if necessary.
NOTE:
- When fitting new pistons to a cylinder block, check for correct piston to bore clearance, honing the bore if necessary. Bottom of piston skirt/bore clearance should be 0.018-0.033 mm (0.0007-0.0013 in).
- The temperature of the piston and cylinder block must be the same to ensure accurate measurement. When reboring the cylinder block, the crankshaft main bearing caps must be fitted and tightened to the correct torque.
Measuring Cylinder Bore:
3. Check the cylinder bore dimension at right angles to the piston pin 40-50 mm (1.5-2 inches) from top.
Measuring Piston Dimension:
4. Check the piston dimension at right angles to the piston pin, at the bottom of the skirt.
5. The piston dimension must be 0.018-0.033 mm (0.0007-0.0013 in) smaller than the cylinder.
6. If new piston rings are to be fitted without reboring, deglaze the cylinder walls with a hone, without increasing the bore diameter, to provide a cross-hatch finish. After honing, thoroughly clean the piston bores to remove all traces of foreign matter.
Refitting Piston to Rod
Land Rover Piston Pin Tool:
1. Using Land Rover tool 18G1150, refit each piston to its connecting rod as follows:
a. Clamp the hexagon body of 18G1150 in a vice, with the adaptor 18G1150 E positioned as in 7d.
b. Remove the large nut of 18G1150 and push the center screw approximately 50 mm (2 in) into the body until the shoulder is exposed.
c. Slide the parallel guide sleeve, grooved end last, onto the center screw and up to the shoulder.
d. Lubricate the piston pin and bores of the connecting rod and piston with graphited oil (Molykore 2). Also lubricate the ball race and center screw of 18G1150.
e. Fit the connecting rod and the piston together onto the tool with the markings aligned if the original pair are being used and with the connecting rod around the sleeve up to the groove.
f. Fit the piston pin into the piston bore, up to the connecting rod.
g. Fit the remover/replacer bush 18G1150/3 with its flanged end towards the piston pin.
h. Screw the stop nut onto the center screw and adjust this nut to obtain an 0.8 mm (0.031 in) end float A on the whole assembly, and lock the nut securely with the screw.
i. Slide the assembly back into the hexagon body and screw on the large nut up to the thrust race.
j. Set the torque wrench 18G537 to 16 Nm (12 ft lb). This represents the minimum load for an acceptable interference fit of the pi5ton pin in the connecting rod.
k. Using the torque wrench and socket 18G 587 on the large nut, and holding the lock screw, pull the piston pin in until the flange of the remover/replacer bush is 4mm (0.157 in) B from the face of the piston. Under no circumstances must this flange be allowed to contact the piston.
CAUTION: If the torque wrench has not reached at least 16 Nm (12 ft lbs) throughout the pull, the fit of the piston pin to the connecting rod is not acceptable and necessitates the fitting of new components. The large nut and center screw of the tool must be kept well oiled.
2. Remove the tool and check that the piston moves freely on the piston pin and that no damage has occurred during pressing.