Cylinder Block - Repair Tapped Holes W/Threaded Inserts

NO.
803

GROUP
21

DATE
3/93

Repair of tapped holes

850

REFERENCE:
TP31804/1 (ENGLISH); 06/92; BS204, B5254 AND B6304 ENGINES TP 31614/1 (ENGLISH); 06/90; ENGINE B19, B23

Repair of tapped holes with thread inserts

Internal threads frequently require repair when working on the cylinder block, intermediate section and cylinder head. Thread inserts can be used for this purpose. In some cases, due to lack of sufficient material thickness around the thread, this is not possible.

This bulletin describes the procedure for repairing tapped holes with thread inserts and also specifies the holes which must not be repaired on the B5254 engine.

WARNING:
The use of protective equipment such as safety goggles and a mask is recommended.





Thread inserts

Thread inserts are made of cold-rolled wire and are formed with ISO thread profiles. The material is a rust and acid-resistant steel. The inserts are designed for installation in tapped holes as specified in the standard thread insert tables in this bulletin.

Each insert is provided with a notched tang which is broken off after installation.

Installation Tools

Refer to TP 31614/1, Engine B19, B23, page 24.

Procedure:

Drill out hole to be repaired.





Select the drill diameter and drilling depth from the thread insert tables in this bulletin.

Hole edges should not be countersunk. Only slight deburring is recommended.





Tap hole with correct tap for thread insert.

Select correct tap for particular material and hole size.

For example, select tap for M10 thread insert for M10 tapped hole.

Tap to correct depth (see table). Blow hole clean.

Select thread insert of correct length (see table).





Position thread insert in installation tool.

Insert should be positioned with tang pointing down.





Install thread insert.

Screw insert on mandrel until driving tang is fully engaged in slot. Screw insert into tapped hole. Top of insert must be 1/4 to 1/2 turn below top surface.





Break off tang.

Break off tang with tang breaker. Do not use installation tool for this purpose.

Remove tang and blow hole clean.

Use bolt to check that thread entry is smooth and that insert is correctly installed.








This table provides information as to which tapped holes in the cylinder head and camshaft cover can be repaired and which thread inserts must be used.

The table also shows the drilling depth and diameter of the holes, as well as the P/Ns of the appropriate thread inserts.











This table provides information as to which tapped holes in the cylinder block and intermediate section can be repaired and which thread inserts must be used.

The table also shows the drilling depth and diameter of the holes, as well as the P/Ns of the appropriate thread inserts.

Note that holes designated B2, V3, H4, H5, BV3, BV5, BV10 and BV21 must not be repaired with thread inserts.