Disassembly and Inspection

Disassembling The Crankshaft Assembly

Special Tools: 999 5746, 999 5679

NOTE: As the illustrations in this service information are used for different model years and/or models, some variation may occur. However, the essential information in the illustrations is always correct.

Preparation

Remove

- the oil trap
- the knock sensors (KS)
- the front engine mounting
- the oil pressure switch.

Remove

- the bearing retainer for the right drive shaft
- the oil cooler and the rubber seals.

Removing The Oil Filter And Oil Pan

- Remove the oil filter. Use tool 999 5679.
- Remove the screws securing the oil pan to the intermediate section.
- Carefully tap the side of the oil pan with a rubber mallet.
- Lift out the oil pan.

Removing The Suction Pipe From The Oil Pump

- Remove the O-rings from the oil ducts.
- Remove the screws securing the suction pipe to the intermediate section.
- Work loose and lift out the suction pipe.
- Remove the suction pipe O-ring.
- Check the pipe and the strainer.

Checking Markings

- Install the two old screws for the flywheel and carrier plate at the rear edge of the crankshaft.
- Turn the crankshaft so the piston in cylinder 1 is at bottom dead center (BDC).
- Check that there are markings on the cap and connecting rods. Check which way the markings are positioned (exhaust and intake side). Make a note of this.
- If necessary mark with a center punch or a number punch.

New Connecting Rod

- 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.

CAUTION: If the cap is turned the wrong way and tightened, the structure of the fracture surface will be damaged and the connecting rod must then be discarded.

NOTE: Blow the fracture surface clean with compressed air before reinstalling the cap.

Removing The Pistons From The Cylinder Block

- Remove the screws for the connecting rod cover.
- Lift off the cover. Ensure that the bearing cover comes with it.

CAUTION: The bearing covers are not interchangeable. Also note the position of the bearing caps in relation to the rotation of the crankshaft.

- Install tool 999 5746 in the connecting rod. Press out the connecting rod and piston.
- Hold by hand so that the piston does not fall to the floor. Ensure that the bearing cover comes with it.
- Place the piston and connecting rod in such a way that they can be reinstalled in the correct cylinder.
- Continue with cylinders 2, 3, 4 and 5 as above.

CAUTION: The bearing covers are not interchangeable. Also note the position of the bearing caps in relation to the rotation of the crankshaft.

Removing The Screwed Joint From The Intermediate Section

- First remove the M7 screws from the intermediate section.
- Then remove the M8 screws. Start at the outer edges and work alternately towards the center.
- Remove the M10 screws in the same way.

Separating The Intermediate Section From The Cylinder Block
- Carefully pry the intermediate section from the cylinder block so that there is a gap of approximately 6 - 8 mm.
- Then carefully tap off (on the exhaust side) the intermediate section with a rubber mallet.
- Lift out the intermediate section. Ensure that the bearing covers for the intermediate section come with it.

CAUTION: The bearing covers are not interchangeable.

- Also note the position of the upper half of the axial bearing for the direction of rotation of the crankshaft.

- The crankshaft must not now be turned.
- Ensure that the screws for the flywheel and carrier plate, which were installed earlier, are properly tightened. Lift them and the front of the crankshaft.
- Carefully lift the crankshaft straight up.
- Remove the remaining bearing covers.

NOTE: The bearing covers for the different bearing recesses are not interchangeable.

Removing The Piston Cooling Valve And Nozzles

- Remove the piston cooling valve at the front of the engine.

- Remove the piston cooling nozzles.

Cleaning

- Clean the gasket surfaces on the cylinder block, intermediate section and oil pan.
- Use a razor blade or a gasket scraper and/or gasket solvent (P/N 116 1440).

WARNING: A fume hood or extractor must be used when using gasket solution.

Measuring The Crankshaft Assembly

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.

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.

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.

Checking The Piston Diameter

Use a micrometer and Vernier caliper.

Calculating The Running Clearance Of The Piston

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: See Assembly.

- Carefully push out the lock-ring using a groove-cut chisel.

WARNING: The snap ring can easily come off. Wear protective goggles.

- 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.
- If the play is too great measure the piston pin.
- Use a micrometer.

New Connecting Rod

- Visually check the bearing shells.
- If in doubt measure out-of-round. Use a bore gauge.

Checking The Connecting Rod In A Connecting Rod Aligner
- Check for out-of-true and twisting.

CAUTION: Check that the aligner fork is unburred and round at the handle.

- Remove and apply the expander at the big end between each alignment operation.