Engine Components / Cylinder Head

Pressure Control Valve In Intake System:

Engine components / cylinder head

Cylinder head
The 4-valve cylinder heads of the M62 basically correspond in design to those of the M60, however, they are not a common part. To facilitate external differentiation, the lettering M60 or M62 as well as the relevant capacity variant (e.g. B35) are cast in the unmachined blank.

M62 Cylinder Head:

Cylinder head gasket
The cylinder head gasket is asbestos-free. In contrast to the cylinder head gasket of
the M60, it no longer covers the area of the timing case cover. A new rubber formed gasket is now used in this area (refer to timing case cover). For this reason, the identification designation of the cylinder head gasket (3.5 I /4.4 I) has been relocated towards the rear.

Cylinder head cover
The cylinder head cover is made of magnesium.
Care must be taken to avoid damaging the surface of the magnesium cylinder head covers as surface damage increases the risk of corrosion.

Camshafts
Two overhead camshafts are allocated to each cylinder head. In the same way as the camshafts of the M60 engine, they are designed as solid shafts made of high- carbon steel casting.

The angle position of the engagement dihedron of the camshafts has been adapted to the existing M60 engagement tools. In this way, the M60 engagement tools can also be used for setting the M62 camshafts.

Cylinder Head With Camshafts And Oil Lines:

Camshaft identification
As on the M60, the camshafts are identified by punched alphanumeric combinations
(E1-4, A1-4, E5-8, A5-5).

Valve train
The main aim in the design of the valve train was to reduce the moved masses. The
masses of the hydraulic tappets, the valve springs and of the upper valve spring retainer have been considerably reduced in conjunction with lower frictional torque and noise reduction. This has made it possible to achieve lower frictional torque and reduction in noise.

Valves
With regard to their dimensions and weight, the valves are identical to those on the M60 (common part M60).

HVA bucket tappets
The diameter of the HVA bucket tappets has been reduced (M60: (35 mm / M62: (33 mm). In this way it has been possible to reduce the weight by 32g to 48g (M60: 80g)(common part M52). These are INA bucket tappets, self-venting with carbon nitrited cam surface.

Valve springs
The use of conical single valve springs has made it possible to reduce the moved masses even further.

Spring retainer
The weight of the top spring retainer has also been optimized (common part M44 and M52). The bottom spring retainer is a common part with M52.

As a whole, a distinct reduction in weight of the valve train has been achieved by these measures as illustrated in the table below.







Timing drive

Primary drive
To facilitate precision optimization with regard to noise, weight and friction, the primary drive is transmitted via a single roller chain (M60: double roller chain) from the crankshaft to the inlet camshaft. The primary drive sprockets are rubberized to enable low-noise engagement of the chain.

Camshaft sensor wheel
A sensor wheel with 4 sensor markings for identifying cylinder number 1 ([1][2]DME) is mounted on the inlet camshaft sprocket for cylinders 1-4. In contrast to the M60 (inductive position sensor), a hall sensor is used as the camshaft position sensor on the M62 engine.

Due to the new design of the camshaft position sensor wheel, positioning of the sensor wheel for the camshaft drive has also been newly defined. The camshaft sensor wheel now features a mark (notch). Particular care must be taken during assembly to ensure that this mark faces downward with respect to the cylinder axis. For more details, refer to the repair instructions.

M62 Camshaft Sensor Wheel:

Deflection rail for primary chain
The deflection wheel in the V-chamber has been replaced on the M62 by an aluminium deflection rail with clip-on plastic track. The chain is tensioned by means of a hydraulic chain tensioner with a pressure limiting facility.

M62 Engine With Deflection Rail For Primary Drive:

Due to the use of a deflection rail (instead of the deflection wheel), during assembly of the primary drive, modified torque values for pretensioning the rail must be observed (refer to repair instructions).

Secondary drive
The secondary drive is also based on a single roller chain. It extends from the inlet camshafts to the exhaust camshafts.
A hydraulic chain tensioner is integrated on each cylinder head

M62 Cylinder Head With Single Roller Chains:

Timing case cover
As on the M60, the timing case covers are attached at the cylinder heads and at the
central crankcase.

The sealing system is new:
The two upper timing case covers are sealed with respect to the cylinder head and the lower timing case cover by means of a rubber formed gasket. This rubber formed gasket achieves better tolerance compensation and acoustic decoupling between the lower and upper timing case covers.

Due to the use of the modified gasket, a new procedure for assembling the upper timing case cover must be observed in order to achieve the optimum sealing effect. Refer to assembly not in repair instructions!

The lower timing case cover is sealed with respect to the crankcase by means of a flat gasket.