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We’ve experienced broken head bolts on some late model GM engines.
Any solutions?

The AERA Technical Committee offers the following information on a recently available bolt extractor kit for 2002-2006 GM 2.8, 3.5 and 4.2L VIN 8, 6 and S engines. This L-style engine family features an aluminum block and cylinder head.

It has been reported that cylinder head bolts or main bearing cap bolts may break during repair procedures. Interaction between a bolt and parent material during certain operating conditions may cause the bolt to bind or break during the removal process. The following information is supplied to help reduce the likelihood of bolt breakage during the removal process.

Prior to removing the cylinder head or main cap bolts, perform the following procedure:
Using an appropriate sized punch and hammer, rap on the head of each bolt several times. The vibration produced by this procedure assists in successful removal of the bolt.


If breakage occurs, a broken bolt extractor kit is now available from GMSPO (p/n EN47702) to assist in removing the remaining bolt segment. (See Figure 1)
The bolt extractor kit provides the following components to assist in removal of the broken bolt segment:

  1. One 5/32″ reverse twist drill (p/n EN-47702-6).

  2. One double-ended drill pilot insert (p/n EN-47702-1), which ensures a straight drilling procedure.

  3. Drill pilot inserts for larger diameter head or main cap bolts (p/n EN-47702-2), which ensure a straight drilling procedure.

  4. Bolt extraction # 3 EZ out (p/n EN-47702-3), for use after the drilling procedure.

  5. Bottom tap (M11 X 2), p/n EN-47702-5, for use to chase the head bolt threads after bolt has been removed.

  6. Bottom tap (M10 X 1.5), p/n EN-47702-4, for the main bolts to chase the threads after bolt has been removed.


I’ve noticed two different style injector-pump mounting bolts on 1.9L Volkswagen diesel engines. What’s the difference?

The AERA Technical Committee offers the following information regarding different injection pump mounting bolts for 1999-2004 Volkswagen 1.9L ALH diesel engines. There have been two different style bolts used and the amount of torque required to install those bolts is also different.

The two versions of bolts are visually identifiable to help determine which torque value to use. Specific use of each bolt is also recommended by Volkswagen any time the bolts have been removed.

Version A – Clearance cut on thread shaft and point. Use with injection pump sprocket: p/n 038 130 111 A. Torque bolts to 14 ft.lbs. (20 Nm) plus an additional 1/4 turn (90°). Note: This bolt is designed as a screw with reduced shank and must always be replaced.
Version B – Securing bolts without clearance cut on thread shaft and point. Use with injection pump sprocket: p/n 038 130 111 B. Torque bolts to 18 ft.lbs. (25 Nm). Securing bolts are not to be replaced unless damaged.

For information on receiving all of AERA’s regular monthly technical bulletins and other association services and benefits, call toll free 888-326-2372 or send an e-mail to [email protected]. AERA’s Web site is www.aera.org.

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