Measuring the Crankshaft Assembly

Measuring the crankshaft assembly

Note! Some variation may occur. However, the essential information in the illustrations is always correct.

Measuring the crankshaft




Use a micrometer.
Measure the out-of-round and taper of the bearing journal. Measure at a number of points laterally and longitudinally.




Values for crankshaft bearing pins (big-end bearing pins) main bearing pins Refer to: Engine, B6304T2 Specifications, Mechanical

Check the out-of-true of the crankshaft




Use a dial indicator and magnetic holder.
Position the crankshaft with the two outer main bearings in the V block.
Turn the crankshaft and measure the radial runout on the other main bearing journals.
Values Refer to: Engine, B6304T2 Specifications, Mechanical

Removing the piston rings




Use piston ring pliers.
Remove coke deposits. Scrape the piston ring grooves clean with a groove cleaner or a broken and filed piston ring.
Check for damage, wear and cracks.

Checking piston ring axial clearance




Use new piston rings.
Values Refer to: Engine, B6304T2 Specifications, Mechanical

Checking the piston diameter




Use a micrometer and vernier calliper.
Values Refer to: Engine, B6304T2 Specifications, Mechanical

Calculating the running clearance of the piston




Values Refer to: Engine, B6304T2 Specifications, Mechanical

Disassembling connecting rods and pistons




Check first that the piston and connecting rod are marked.
Piston marking: Scrape the piston pin clean. If the marking is unclear, mark the piston with the cylinder number and an arrow pointing to the front of the engine. Use a marker pen.
Connecting rod marking: Refer to: Engine, B6304T2 Specifications, Mechanical.
The lock ring can easily fly off. Wear protective goggles!
Carefully push out the lock-ring using a groove-cut chisel.
Press out the piston pin with your thumb.
Clean and check the connecting rods, caps and screws for damage, signs of wear or cracks.

Checking the alignment of the piston pins in the pistons




The piston pin must not be loose. It should be possible to push it through the hole using thumb pressure.
Replace the piston if the play is too great.

Checking the alignment of the piston pins in the connecting rods




The piston pin should slide through the hole with light thumb pressure.
In case of too much play, check-measure the piston pin. Use micrometer.
Diameter of piston pin Refer to: Engine, B6304T2 Specifications, Mechanical

New connecting rod




If the cap is turned the wrong way and tightened, the structure of the fracture surface is damaged and the connecting rod must be discarded.
Blow clean the fracture surface with compressed air before reinstalling the cap.
A new connecting rod has been introduced on certain engines.
The mating surface between the cap and the connecting rod is not machined. It is aligned through a dedicated fracture surface.

Checking the bearing recess in the connecting rod big end




Visually check the bearing shells.
If in doubt measure out-of-round. Use a bore gauge.
Diameter of bearing position Refer to: Engine, B6304T2 Specifications, Mechanical

Checking the connecting rod in a connecting rod aligner
Check that the aligner fork is free from burrs and round at the handle.
Remove and apply the expander from the big-end between each alignment operation.
Check for out-of-true and twisting.