Repair Procedure

Caution:
When disassembling cylinder head and performing cleaning procedure, always use protective eyeware.

Following Repair Instruction 11 12 505/506, remove cylinder heads from engine.





To disassemble cylinder head, refer to Repair Instruction 11 12 503. Mount cylinder head on special tool 11 1 065. Remove camshafts.





Using tool 11 3 250, remove the bucket tappets.





Utilizing the listed special tools, compress exhaust valve spring.





Remove the valve retainers, and remove valve spring. For reassembly purposes, ensure that all removed spring assemblies and bucket tappets are arranged together in order of removal.





Using special tool, remove exhaust valve guide seals.





Push on valve stem until edge of stem is flush with top of valve guide (1).





With the valve stem so positioned and using a dial indicator mounted to a suitable holding fixture, rock valve back and forth within guide to measure valve tilt clearance of each exhaust valve. Movement should not exceed 0.5 mm. This procedure, outlined in RA 11 12 595, ensures that the valve stems and guides are within acceptable limits.

Note:
If heavy carbon deposits are found in the cylinder head, it is highly probable the other cylinder head will soon develop the same condition. For that reason, it would be advisable to remove the other cylinder head for cleaning.





Using the drill bit (2) supplied in the kit, drill a hole in the 10 mm core plug for the main secondary air supply passage located in the rear of the head (1).





Using the core plug remover (2) and a 10 mm socket, thread screw portion of tool into hole and continue to turn clockwise until plug is removed. On the right side cylinder head, perform same procedure to remove core plug from the front of the head.

Note:
The left side (cylinder 5-8) cylinder head does not have a front core plug.





Using the 10 mm brass brush (2) from the kit mounted in motorized drill, clean out main secondary air delivery passage 1). Blow out the passage with an air nozzle and shop air and repeat the deaning procedure until no more carbon is present.





Locate the secondary air distribution ports under the removed exhaust valve. Insert the reamer tool (2) in the port (1) and rotate in clockwise direction until no further resistance is felt and the tool has reached the bottom of the passage. Repeat procedure with remaining 7 ports (per cylinder head).





Finish the port clean up by using the small 4 mm nylon brush (2) in
conjunction with a motorized drill in each of the 8 (per cylinder head) delivery ports (1). Blow out passages with an air nozzle.





Using the core plug installer (3) and a hammer (4), install new core plugs (2) into secondary air distribution passages (1). Core plugs (PN 11 12 1 736 330) have to be ordered separately (Qty: 3 per vehicle).





Prior to cylinder head reassembly, reinstall the back-pressure tool (2) into the passage (1) and retest. The reading on the DISplus should be close to the base atmospheric reading (1 bar) and air flow should be present at all delivery 8 ports.





Install protective sleeve over end of valve guide and place new valve seal over sleeve.





Press on valve seal using the tool indicated. Reassemble cylinder heads and reinstall on the engine.