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Assembly of pistons and connecting rodsBefore installing the connecting rods they need to be checked for distortion and twisting with a suitable testing instrument. Position the piston and the connecting rod according to the installation direction. The oiled pin is carefully inserted into the pin bores of the piston and into the connecting rod eye of the connecting rod. For pistons with tightly toleranced pin bore, insertion of the pin is easier if the piston is heated to approx. 40 °C.
For swimming pins
Whether the rings have safely locked into the grooves can be checked by slightly turning them. The joint of the retention must always be in direction of the piston stroke.
Assembly of connecting rod with fixed pin
Checking the piston ringsCheck whether the rings can be freely (turned) rotated in the ring grooves.
For piston rings marked with “TOP”, the marking must point to the piston crown. This ensures the intended function is working. The joint ends of the spiral expander should always be exactly opposite the ring joint for spiral expander rings. For spiral expanders with Teflon sheath, the sheath rests against the ring joint. In addition, for spiral expander rings with locating hook it is important that the locating hook is locked into the oil slot.
1 Oil slot 2 Locating hook During transport the spiral ends are untightened and can slip one above another. The position might need to be corrected before installation. Both colour markings at the spiral ends must be visible. If they are not visible, the spiral has overlapped and the ring is not working. The ring joints of the 3-part oil control ring (the two steel rails and the expander spring) must be turned against each other by 120° each before installation.
Inserting the piston into the cylinder linerClean the cylinder block thoroughly. Make sure that all gliding surfaces are free from dirt and well oiled. Press the piston rings together with a squeezer to enable the piston gliding into the cylinder liner without resistance. For Diesel engines measure the gap dimension or piston's amount of protrusion and always adhere to manufacturer's specifications. You’ve seen it—somebody trying to install pistons and ending up with pinched or broken piston rings or so much oil in the bore their shoes are drenched. It doesn’t have to be that way if you use the easy-to-follow procedure outlined in the
photo captions. Happy piston installin’!
Wipe the cylinder bores with a clean, lint free towel and apply a small amount of conventional (non-synthetic) oil to the walls. Apply a liberal amount of oil to the wrist pins and piston rings as well. You don’t need to drench the piston in oil—use enough to lubricate the rings as they pass through the piston ring compressor. No need to dunk the piston and ring assembly in a quart of oil! There are two basic types of ring compressors. Expander models clamp over the piston and are tightened in place. Tapered compressors progressively tighten the rings as the piston is pushed through the tool into the bore. Whichever one you use, liberally coat the compressor with oil. Again, it doesn’t have to be dripping wet. Rotate the crankshaft so the rod journal for the piston you’re installing is at Top Dead Center. Place the piston/ring compressor combination over the cylinder bore. Always do the following before sliding the piston into the bore: • If the piston is domed, the dome should be to the outside of the block • Check that the chamfer on the connecting rod (and rod bearing) is facing the fillet radius on the crankshaft • Make sure the oil rings’ expander ring end gaps haven’t overlapped • Cover rod bolt ends with protectors to prevent crank damage during installation • Coat the connecting rod bearings with assembly lube It’s often possible to hand-push the piston and rod assembly into the bore, guiding the rod so that it falls in place over the crankshaft rod journal. Other times you will need to very light tap the assembly in with the handle end of a clean plastic hammer. If you need excessive force to push the piston through the ring compressor into the bore, it usually means the oil ring expander rails are overlapped. Rotate the engine on the engine stand. Coat the bearing in the rod cap end with assembly lube and install. You can install the rod cap nuts and torque to specifications at this point, provided you’ve checked the bearing clearances. Repeat this sequence on the rest of the piston/rod assemblies.
left right Tools Required
[important]Which complicated install would you like to see us break down next? Please tell us in the comments section below.[/important] Does it matter which way a piston ring goes?Not only must the ring be installed with the proper side toward the top of the piston, but it is also imperative that the ring be installed in the proper groove.
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How to fit pistons to block
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