For Cylinder Head Bolts

Special tools
Drilling jig for threaded bores for 117 589 02 23 00
cylinder head bolts in crankcase

Tap with guide shaft 117 589 00 70 00

Conventional tools
Heli-Coil tap M 10 Item No. 0140 0100104

Heli-Coil threaded insert M 10 Standard item No. 0130 0100025 (part No. 000 997 58 15) e.g. D-4800 Bielefeld 14

Heli-Coil hand installer M 10 Item No. 0150 04100001

NOTE: If damaged threads are found when removing and installing the cylinder head or the camshafts, Hell- Coil inserts, Part no. 000 997 58 15, should be inserted for all the cylinder head bolts in the crankcase of the respective bank of cylinders.

! The threaded inserts have a (screwed in) length equal to 2.5 times the diameter of the cylinder head bolts (14 turns of the thread).

Use an angle drilling machine with a chuck for 10 mm dia. drills for difficult threads to avoid having to remove the engine.





Important: The tapped holes 15, 7, 1, 8 and 17 for the M 10 x 165 cylinder head bolts at the camshaft bearings are drilled at an angle in the crankcase.





These threaded holes are not vertical to the crankcase mating surface, but at an inclination of 1° 52' to the engine outside.

In order to prevent pressure points on the cylinder running surfaces due to the relatively long Heli-Coil inserts, the respective core holes must be drilled vertically or at 1° 52' inclination using the drilling jig.

Reconditioning





1 Bolt drilling jig onto the cylinder bank concerned.
2 Cover cylinder bores, coolant openings and chain case (minute aluminum-silicon chips damage the cylinder running surface and the piston).





3 Using an HSS spiral drill 10 mm dia., drill core hole approx. 37 mm deep while lubricating with honing oil.

Core hole diameter should be a minimum of 10 mm and a maximum of 10.3 mm.





4 Unscrew drilling template and extract or blow out swarf.





5 Pre-tap Heli-Coil mounting thread with the thread tap with guide stud Part No. 117 589 00 70 00 as deep as possible. Lubricate the thread tap with honing oil when performing this step.
6 Carefully blow out swarf.
7 Tap Heli-Coil mounting thread with Heli-Coil M 10 tap (OD 12.0 mm), Part No. 01 400 100 104, approx. 35 mm deep. Lubricate the thread tap with honing oil when performing this step.
8 Carefully extract or blow out swarf.





9 Screw in oil-coated Heli-Coil threaded insert (1), part No. 000997 58 15. (Heli-Coil standard item No. 01 300100025), using hand installer M 10 (2), item No. 0150 0410000-1.

To do so, screw Heli-Coil insert (1) with the driving end to the front into the hand installer (2) until the first winding projects 3/4. Align the hand installer over the tapped hole and screw in the Helicoil insert (1) without pressure by turning the spindle.





CAUTION: The uppermost thread must be positioned approx. 4 mm below the crankcase mating surface.

10 Screw a cylinder head bolt into the inserted thread and check for misalignment and easy operation.

The screw-in depth should be approx. 29 mm.

NOTE: The driving end of the Heli-Coil threaded insert is not removed as is usual, but remains on the threaded insert.