Cylinder Head
Cylinder Head
Removing
• All cable ties opened or cut during engine removal must be reinstalled at the same locations during installation.
- Remove engine. Refer to: Vehicles with manual transmission => [ Engine, Manual Transmission, Removing ] Engine, Manual Transmission, Removing, vehicles with automatic transmission => [ Engine, Removing ] Engine, Automatic Transmission, Removing and Installing.
- Leave engine with transmission installed on the scissor lift platform (VAS 6131 A).
- Remove camshaft timing chains from camshafts. Refer to => [ Camshaft Timing Chains, Removing from Camshafts ] Camshaft Timing Chains, Removing From Camshafts.
- Remove glide track - 1 - at left cylinder head.
- Remove chain tensioner - 2 -.
- Remove glide track - 1 - at right cylinder head.
- Remove chain tensioner - 2 -.
- Loosen cylinder head bolts in the sequence - 1 to 10 -.
- Remove cylinder head and place it on a soft surface (foam).
Installing
• Replace cylinder head bolts.
• During assembly, replace self-locking nuts and bolts.
• Always replace bolts that are tightened to torque as well as O-rings and gaskets.
• Carefully remove residual sealant from cylinder head and cylinder block. Make sure that no long scrapes or scratches result.
• Carefully remove all grinding and sanding residue.
• There must not be any oil or coolant in the blind holes for the cylinder head bolts in the cylinder block.
• After installing a replacement cylinder head with camshafts installed, oil contact surfaces between roller rocker levers and cam lubricating surfaces after installing cylinder head.
• Do not remove plastic bases protecting free up valves until immediately before installing cylinder head.
• Cylinder heads with cracks between the valve seats, or between the valve seat and the spark plug threads, can continue to be used without reducing the service life, as long as the cracks have a width of max. 0.3 mm, or only the first 4 threads of the spark plug threads are cracked.
• Only unpack new cylinder head gasket immediately prior to installation.
• Handle gasket with extra care. Damages to the silicone layer and in areas of recesses may result in leaks.
• Install cylinder head gasket onto guide sleeves. Marking "oben" (top) or part number must face toward cylinder head.
• Secure all hose connections using hose clamps appropriate for the model type.
• When replacing the cylinder head or cylinder head seal, all of the coolant and engine oil must be replaced.
• After working on the valvetrain and lifters, carefully rotate the crankshaft by hand at least 2 full revolutions before starting to be sure that valves do not strike the pistons.
• During installation, all cable ties must be re-installed at the same location.
- Check whether camshafts of both cylinder heads stand in TDC position.
• Slits - arrows - at front in camshafts must stand parallel at same height with upper edge of cylinder head.
• Crankshaft holder (3242) must be installed.
- Position cylinder head gasket.
• Pay close attention to alignment bushings in cylinder block - arrows -.
• Pay attention to installation position of cylinder head gasket, marking " oben" (top) or part number must face toward cylinder head.
- Install cylinder head.
- Insert new cylinder head bolts and tighten by hand.
- Tighten cylinder head bolts in 4 stages in the tightening sequence shown as follows:
- Using torque wrench, tighten to 30 Nm.
- Using torque wrench, tighten to 60 Nm.
- With a rigid wrench, 90° (1/4 turn) additional turn.
- With a rigid wrench, 90° (1/4 turn) additional turn.
• There is no requirement to retighten the cylinder head bolts after repairs.
The rest of installation is in reverse order of removal, note the following:
- Install camshaft timing chains => [ Installing ] Camshaft Timing Chain.
- Install engine. Refer to: Vehicles with manual transmission => [ Engine, Installing ] Engine, Manual Transmission, Removing, vehicles with automatic transmission => [ Engine, Installing ] Engine, Automatic Transmission, Removing and Installing.
- Change engine oil.
- Replace coolant. Refer to => [ Filling ] Procedures.
Tightening Specifications
* Replace bolts.
* 90° corresponds to one quarter rotation.