Valve Clearance: Adjustments
ADJUSTING SPECIFICATIONS:Cold engine: (up to 50°C coolant temperature)
Intake: 0.10 - 0.20 mm
Exhaust: 0.25 - 0.35 mm
Warm engine: (60 - 80°C)
Intake: 0.15 - 0.25 mm
Exhaust: 0.30 - 0.40 mm
TORQUE SPECIFICATIONS:
Cylinder head cover cap nuts: 9 Nm
Screws, ignition cable cover: 20 - 4O Nm
Nuts, camshaft bearing brackets 21 Nm
Bolts, timing gear to camshaft 12 Nm
SPECIAL TOOLS:
Tools for checking valve clearance.
Additional tools for adjusting valve clearance.
PROCEDURE:
NOTES:
Camshafts must be removed to adjust valve clearance.
Check and record all valve clearances before making adjustments.
Recheck all clearances after making adjustments.
If both camshafts are to be removed at the same time mark each camshaft so they are reinstalled in the location they came from.
WARNING!
Because of the high ignition voltage, it is dangerous to touch ignition components (ignition coil, ignition cables, spark plug connector, module push connectors) when:
^ the engine is running
^ the engine is being started
^ the key in in position 2 while the engine is being turned manually
Rotating Engine:
A By hand:
- After turning off ignition disconnect crankshaft position sensor (L5, green cable) from ignition control module.
- Use socket wrench adaptor (27 mm 1/2" drive) and ratchet, on the vibration damper bolt and rotate engine clockwise.
CAUTION:
The engine must not be turned via the camshaft.
Do not turn crankshaft backwards.
B With starter:
- After turning off ignition disconnect crankshaft position sensor (L5, green cable) from ignition control module.
CAUTION:
Before turning engine, pull out fuel pump relay module (N16/4), to prevent fuel from being injected.
- Connect one clamp of remote starter switch to the battery positive terminal.
- Disconnect connector (X27) from plug connector 50.
- Connect plug from adapter cable (01) 124 589 36 63 00.
Checking:
NOTES:
Check or adjust valve clearance with engine cold or warm.
Check all valve clearances before adjusting any valve
clearances.
Note layout of intake and exhaust valves.
E = Intake
A = Exhaust
Removing cylinder head cover:
- Remove securing screws (709), remove ignition cable valley cover (708).
- Pull off the spark plug connectors and lay the ignition cable to the side.
- Loosen hose clamp (712) and pull off the hoses (711 and 713) on the cylinder head cover (85).
- Remove cap nuts (101) and remove cylinder head cover.
Measuring valve clearance:
- According to engine temperature and valve (intake or exhaust), try to pull the corresponding feeler gauge blade (minimum and maximum thickness) between the bucket tappet and the cam base circle.
- Measure valve clearance between bucket tappet and cam base circle of camshaft (arrows), by rotating the engine to position the camshaft in such a way that the cam points up (base circle on bucket tappet).
- Valve clearance is set correctly if the feeler gauge blades, minimum or maximum thickness, can be pulled through with some resistance (e.g., intake with cold engine, feeler gauge blade 0.10 or 0.20 mm).
- If the valve clearance is out of specifications use the appropriate feeler gauges to determine the actual valve clearance.
- Record the clearance and identify the cylinder and valve the clearance is for, this record will be used during adjustment.
- If the feeler gauge with the minimum thickness cannot be pulled through, or if the feeler gauge blade with the maximum thickness can be pulled through lightly, adjust the valve clearance.
Adjusting:
Removing the camshaft:
- Turn the engine to the TDC position of the first cylinder; the holes (2 mm, arrows) in the timing gears must be opposite each other.
- Mark the camshaft, timing chain and timing gear for alignment.
- Remove timing chain tensioner.
- Remove retaining screws (329, four for each timing gear).
- Using a plastic mallet, carefully tap the camshaft toward the rear to separate it from the timing gear center collar.
NOTE: If both camshafts are taken out at the same time, mark each for later identification because they are identical.
- Unscrew fastening nuts (73) and take off bearing brackets (66).
- Note the markings on the bearing brackets so they can be reinstalled in their original locations.
- Remove the camshaft.
- Pull out the corresponding bucket tappet (219) with the magnetic lifter.
- Take out adjustment disk (220).
- Determine the correct thickness for the replacement adjustment disk.
Determining replacement disk thickness:
- Measure the removed adjustment disk.
- Determine the difference of the measure valve clearance and the desired valve clearance.
- Add/subtract the clearance difference to/from the removed adjustment disk thickness.
^ If valve clearance is excessive, add the difference to the thickness of the removed disk.
^ If valve clearance is too small, subtract the difference.
- Install an adjustment disk of this thickness.
Example
Intake, engine cold.
Measured value 0.25mm
Desired average value 0.15mm
Difference +0.10mm
Thickness of removed disk 2.8mm
Add the difference +0.10mm
Thickness of new disk 2.9mm
NOTE: With an intake valve clearance of less than 0.10 mm always put in a 0.10 mm thinner disk.
Reassemble:
- Set disks in the valve spring retainer.
- Oil and install bucket tappets.
- Oil and install camshaft in reverse order of removal.
- Before tightening the camshaft on the timing gear, carefully tap the camshaft toward the front on the center collar of the timing gear with a plastic hammer.
- Observe previously inscribed alignment marks.
NOTE: The camshaft can be secured to the timing gear in only one position.
- The camshaft bearing brackets are numbered for identification:
Intake camshaft identification numbers 7-10.
Exhaust camshaft identification numbers 2-5.
- The stamped identification numbers must be adjacent to the inside stud bolts.
- Tighten all nuts equally, in steps.
- Reinstall timing chain tensioner.
- Check the valve clearance again (check measurement).
- Check cylinder head cover gasket (97) and sealing rings (98) for damage and replace if necessary.
- Replace cylinder head cover in reverse order of its removal. Gradually tighten cap nuts in steps to 9 Nm.
- Route ignition cable according to the symbols and guide ribs in the ignition cable valley.
NOTE: Check the valleys for foreign matter before the spark plug connectors are reattached.
- Check for leaks with engine running.