Information on Torque to Yield Bolt Breakage and use of Bolt Extractor Tool Kit Part Number EN-47702 for Removing broken Cylinder Head or Main Bearing Cap Bolts on Inline Truck Engines

This bulletin is being revised to add additional information on torque to yield bolt breakage and use of bolt extractor tool kit. The model year and engine usage has also been updated. Please discard Corporate Bulletin Number 05-06-01-026 (Section 06 -- Engine/Propulsion System).

A Torque To Yield (TTY) bolt, like a cylinder head bolt or main bearing cap bolt, may break during repair procedures. Interaction between a TTY bolt and threads may cause the bolt to bind or break on removal.

Prior to removing the cylinder head or main cap bolts, perform the following procedure:

Using an appropriately sized punch and hammer, rap on the head of each bolt. The vibration produced by this procedure will assist in successful removal.

If a head bolt or main bolt breaks during engine disassembly, a broken bolt extractor kit (EN-47702) has been released to assist in removal of the remaining bolt segment. Many times the remaining bolt segment will back out easily with a pick tool or a reverse twist drill bit.

Bolt Replacement & Tightening

Important: Never reuse TTY main bearing or cylinder head bolts. Always make sure that the engine block threaded holes are clean and do not place oil or threadlocker on the bolts.

Utilize a thread chase tool followed by cleaning with dry compressed air to insure threads are clean and dry prior to installation of new TTY bolts. Bolts that creak and snap while tightening will fail due to excessive torque caused by threads contaminated with debris, antifreeze or oil. Trace amounts of oil or antifreeze will cause this condition. In extreme cases the threads may need additional cleaning with a non-residue cleaner like a brake clean product followed by drying with clean & dry compressed air.

The bolt extractor kit EN-47702 provides the following components to assist in removal of the broken bolt segment:

1. One 5/32" reverse twist drill - part number EN-47702-6
2. One double-ended drill pilot insert - part number EN-47702-1 (ensures a straight drilling procedure)
3. Drill pilot inserts for larger diameter heads or main cap bolts - part number EN-47702-2 (ensure a straight drilling procedure)
4. Bolt extraction #3 EZ out - part number EN-47702-3 (after the drilling procedure)
5. Bottom tap (M11 X 2) - part number EN-47702-5 (for the head bolts to chase the threads after the completion of bolt removal)
6. Bottom tap (M10 X 1.5) - part number EN-47702-4 (for the main bolts to chase the threads after the completion of bolt removal)