GM Service Manual Online
For 1990-2009 cars only
Table 1: Specification Chart
Table 2: Tool Numbers Chart

Installation


Object Number: 870970  Size: SH

Caution: Protect yourself by wearing safety glasses, earplugs, a respirator, gloves, and safety shoes while performing work on the vehicle.

The following assembly information is used to assemble the Heli-Coil® inserts into aluminum components. Steel components can also have Heli-Coil® inserts if there is enough material thickness.

Drilling Hole

Notice: The drilling depths are maximum and should not be increased. Spark plug thread repairs do not require drilling. The piloted reamer part #5515-14 removes the damaged thread and cuts a new thread simultaneously.

Drill out the damaged threads using the drill specified in the table to a sufficient depth specified in the table.

Tapping Hole M6-M12


Object Number: 870975  Size: SH

Select proper tap specified in table and tap the hole to a sufficient depth that will accommodate the insert required.

Spark Plug

Clean counterbore, walls, and seat. Engage pilot threads and rotate tap until depth collar bottoms out. Remove tap and clear chips from hole.

After tap has been removed use compressed air to blow chips out of hole. Take care not to blow chips into engine.

Inserting Heli-Coil®

M6


Object Number: 870977  Size: SH

Remove mandrel from prewinder, and place insert onto threaded end of mandrel. Place mandrel in prewinder threaded end down and turn into prewinder two turns. Position squarely over hole and rotate mandrel clockwise until upper coil is 1/4 - 1/2 turn below top surface.

M8-M12


Object Number: 870979  Size: SH

Select the proper size Heli-Coil® insert from table. Use the installation tool listed in table and turn the insert clockwise into the hole until the upper coil is 1/4 - 1/2 turn below top surface.

Spark Plug


Object Number: 877417  Size: SH

Notice: Always make sure the piston is at bottom dead center (BDC) to prevent piston damage.

Lube mandrel threads and thread taperset onto mandrel with larger end towards 11/16 hex body until one thread extends beyond the taperset. Install taperset into hole and torque to 68 N·m (50 lb ft). Hold 7/16 hex and loosen 11/16 body 1/2 turn. Remove installation tool.

Heli-Coil® Tang Removal


Object Number: 870981  Size: SH

To remove the tang used for installation, place the square end of a punch on the tang and strike the punch sharply.

Use compressed air to blow chips out of hole. Take care not to blow chips into engine.

Specification Chart

BOLT THREAD

HELI-COIL®

LENGTH

DRILL DEPTH

PLUG TAP

DRILL DEPTH

BOTTOM TAP

DRILL SIZE

M6 x 1

12 mm (0.472 in.)

21 mm (0.827 in.)

16 mm (0.630 in.)

6.25 mm (0.2460 in.)

M10 x 1.5

20 mm (0.787 in.)

29 mm (1.142 in.)

26 mm (1.024 in.)

10.5 mm (0.4130 in.)

M12 x 1.75

24 mm (0.945 in.)

34.5 mm (1.358 in.)

31 mm (1.22 in.)

12.3 mm (0.4840 in.)

Tool Numbers Chart

BOLT THREAD

INSERT P/N

PLUG TAP

INSERT TOOL

M6 x 1

R1084-6-20

2093-6

3747-6

M8 x 1.25

R1084-8-20

2093-8

3747-8

M10 x 1.5

R1084-10-20

2093-10

3747-10

M12 x 1.75

R1084-12-20

2093-12

3747-12

Spark Plug

R5503-14L

5515-14

5511-14