Rocker Arm Assembly: Service and Repair

Camshaft Housing (Left Side Shown) Part 1 Of 3:

Camshaft Housing (Left Side Shown) Part 2 Of 3:

Camshaft Housing (Left Side Shown) Part 3 Of 3:

NOTE: Unless indicated otherwise, coat all aluminum plugs with Optimoly HT (copper paste) and press in flush. Do not use any other lubricant.

Removing And Installing Spray Tube On Camshaft Housing

NOTE: In case of bearing damage and when rebuilding the engine, the spray tubes must always be removed and cleaned thoroughly. If bearings are damaged, the lateral oil ducts must also be cleaned (removed 6.7 mm dia. plug and opposite 6.3 mm dia. balls). The ball may be pushed out with a threaded bar (M5) from the opposite side. Balls that do not retain a press-fit should be replaced by a plug.

Removing The Spray Tubes
Removal
Pre-drill lateral plugs (8.15 mm dia.) and upper plug (12.5 mm dia.) with a 4.8 to 5 mm dia. drill to a depth of approximately 9 mm and tap in an M 6 thread with a bottoming tap. Pull out plug with M 6 screw and spacer sleeve.

Positioning Spray Tube With Auxiliary Tool





Turn original plug (Part No. 993.105.345.00) down to an outside dia. of 12.4 mm. Tap M 5 thread into plug and screw in suitable screws, e.g. M 5 x 35. Push spray tube into camshaft housing. Smaller bores (6 bores) face camshaft. Use auxiliary tool to position spray tube. Coat new plug with Optimoly HT and press in flush.

Installation
Apply a coating of Optimoly HT to the new plug and press in flush.

Installation Position Of Rocker Arms





1 - Inlet rocker arm
Identification:
Valve lifter bore is drilled, plugged with cover and punched (arrow).

2 - Exhaust rocker arm
Valve lifter bore not drilled

Checking Presence Of Sealing Balls





Balls (6) on camshaft housing sealing face, balls (2) on front face (pulley side). 2 lateral balls are only present on engine with air injection.

Sealing The Camshaft Housing Sealing Face

NOTE:
- Use only Loctite 574 to seal
- Loctite 574 hardens only when contact with metal is made and air ingress is prevented.
- After having applied the sealant, bolt up the crankcase sections within approximately 10 minutes since the sealant bead applied directly to the metal surface will otherwise start to cure.

Removing Old Sealant
In case of repairs, the old sealant coat must not necessarily be removed. It is sufficient to de-grease the surface and apply the new coat of sealant after the solvent has evaporated.

New Loctite will soften the old sealant embedded in the machining marks and will cure after assembly.

Should it be required to remove the old sealant, it is recommended to use a fine-mesh wire brush or Loctite adhesive remover 80646.

Applying Sealant
1. For manual application, it is recommended to use a short-pile paint roller and to pour the sealant into a dish with grooves at its circumference (for squeezing excess sealant off the roller).
2. Apply a uniform coat of Loctite 574 to the sealing face of the camshaft housing by using the paint roller. Use a small paint brush to apply sealant to the straight pins around the bolt holes.