Repair Transmission Mounting Bolt Holes With Thread Inserts

Overview
- Engine removed
- Core hole with HSS twist drill - bore out (step 1).
- Metal chips - blow out (step 2).
- Drill (4) with oil return duct - connect (step 2).
- Right cylinder head - remove.
- Oil pan - remove, install.
- Metal Chips in oil duct - blow out from above.
- HELI-COIL mounting thread - tap (step 3).
- Metal chips - blow out (step 4).
- HELI-COIL threaded insert M10 - screw in (step 6).
- Insertion depth - observe (step 5).
- Tang of HELI-COIL threaded insert - break off with a drift, remove.
- Ease of movement of threads - check (step 7).
- Stud bolts - screw into bore 1 and 4 (step 8).

Commercial Tools
- HELI-COIL tap M10
- HELI-COIL threaded insert M10.
- HELI-COIL hand installation tool M10

NOTE: Damaged threads for transmission mounting should be replaced by HELI-COIL standard threaded inserts, with a length corresponding to twice the diameter of the bolts (11 threads).

Procedure





1. Drill core hole approx. 27 mm deep with an 10 mm diameter HSS twist drill.

Minimum core hole diameter 10 mm, maximum 10.3 mm.





2. Blow out chips.

NOTE: Bore (4) merges into oil return duct.
When repairing bore (4), remove and install right cylinder head, refer to Cylinder Head, Service and Repair. [1][2]Procedures
Remove and install oil pan. Service and Repair





NOTE: Blow swarf (metal chips/shavings) from bore (4) out of oil duct from above (arrow).





3. Tap HELI-COIL mounting thread with HELI COIL M10 tap (outer diameter 12.0 mm), approx. 25 mm deep.
Lubricate tap with honing oil when performing this step.

4. Blow out swarf.

NOTE: Bore (4, see step 2.





5. Screw in oiled HELI-COIL M10 standard threaded insert, with the M10 hand installation tool.

NOTE: The top thread must stop approx. 2 mm below the mating surface.

6. Break off tang of HELI-COIL threaded insert with a drift.
7. Examine inserted thread for possible misalignment and for ease of operation of threads by screwing in a bolt.
The insertion depth should be approx. 23 mm.





8. Install stud bolts (1) and (4).

NOTE: The microencapsulated stud bolt (4) seats the oil duct in the crankcase.
The stud bolts lose their sealing effect after being removed. They may only be used once.