Crankshaft - removal and inspection

Engine removal and overhaul procedures / Crankshaft - removal and inspection

Removal
1 Note: If no work is to be done on the pistons and connecting rods, then removal the cylinder head and pistons will not be necessary. Instead, the pistons need only be pushed far enough up the bores so that they are positioned clear of the crankpins. The use of an engine stand is strongly recommended.

2 With reference to Chapter 2A, carry out the following:
a) Remove the crankshaft timing belt sprocket.

b) Remove the clutch components and flywheel.

c) Remove the sump, baffle plate, oil pump and pickup.

d) Remove the front and rear crankshaft oil seals and their housings.

3 Unbolt the pistons and connecting rods from the crankpins, as described in Section 5 (refer to the Note above).

4 Carry out a check of the crankshaft endfloat, as follows. Note: This can only be accomplished when the crankshaft is still installed in the cylinder block/crankcase, but is free to move. Set up a DTI gauge so that the probe is in line with the crankshaft axis and is in contact with a fixed point on end of the crankshaft. Push the crankshaft along its axis to the end of its travel, and then zero the gauge. Push the crankshaft fully the other way, and record the endfloat indicated on the dial (see illustration). Compare the result with the figure given in Specifications and establish whether new thrustwashers are required.

6.4 Checking the crankshaft endfloat using a DTI gauge

5 If a dial gauge is not available, feeler blades can be used. First push the crankshaft fully towards the flywheel end of the engine, then use a feeler blade to measure the gap between cylinder No 2 crankpin web and the main bearing thrustwasher (see illustration).

6.5 Checking the crankshaft endfloat using a feeler blade

6 Observe the manufacturers identification marks on the main bearing caps. The number relates to the position in the crankcase, as counted from the timing belt end of the engine (see illustration).

6.6 Main bearing cap identification markings

7 Loosen the main bearing cap bolts one quarter of a turn at a time, until they can be removed by hand. Using a soft faced mallet, strike the caps lightly to free them from the crankcase. Recover the lower main bearing shells, taping them to the cap for safe keeping. Mark them with indelible ink to aid identification, but do not score or scratch them in any way.

8 Carefully lift the crankshaft out, taking care not to dislodge the upper main bearing shells.

It would be wise to get an assistants help, as the crankshaft is quite heavy. Set it down on a clean, level surface and chock it with wooden blocks to prevent it from rolling.

9 Extract the upper main bearing shells from the crankcase and tape them to their respective bearing caps. Remove the two thrustwasher bearings from either side of No 3 crank web.

10 With the shell bearings removed, observe the recesses machined into the bearing caps and crankcase - these provide location for the lugs which protrude from the shell bearings and so prevent them from being fitted incorrectly.

Inspection
11 Wash the crankshaft in a suitable solvent and allow it to dry. Flush the oil holes thoroughly, to ensure that are not blocked - use a pipe cleaner or a needle brush if necessary. Remove any sharp edges from the edge of the hole which may damage the new bearings when they are installed.

12 Inspect the main bearing and crankpin journals carefully; if uneven wear, cracking, scoring or pitting are evident then the crankshaft should be reground by an engineering workshop, and refitted to the engine with undersize bearings.

13 Use a micrometer to measure the diameter of each main bearing journal (see illustration).

Taking a number of measurements on the surface of each journal will reveal if it is worn unevenly. Differences in diameter measured at 90° intervals indicate that the journal is out of round. Differences in diameter measured along the length of the journal, indicate that the journal is tapered. Again, if wear is detected, the crankshaft must be reground by an engineering workshop and refitted with undersize bearings (refer to Reassembly)

6.13 Measuring the diameter main bearing journals

14 Check the oil seal journals at either end of the crankshaft. If they appear excessively scored or damaged, they may cause the new seals to leak when the engine is reassembled.

It may be possible to repair the journal; seek the advice of an engineering workshop or your VW dealer.

15 Measure the crankshaft runout by setting up a DTI gauge on the centre main bearing and rotating the shaft in V - blocks. The maximum deflection of the gauge will indicate the runout. Take precautions to protect the bearing journals and oil seal mating surfaces from damage during this procedure. A maximum runout figure is not quoted by the manufacturer, but use the figure of 0.05 mm as a rough guide. If the runout exceeds this figure, crankshaft renewal should be considered - consult your VW dealer or an engine rebuilding specialist for advice.

16 Refer to Section 8 for details of main and big-end bearing inspection.