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 during removal. Isuzu has classified the Kent Moore EN-47702 Broken Bolt Extractor Kit as an essential tool.
Prior to removing cylinder head or main cap bolts, perform the following procedure:
- Using an appropriately sized punch and hammer, tap on the head of each bolt. The vibration produced will assist in successful removal.
- If a head or main cap bolt breaks during engine disassembly, use a Kent Moore EN-47702 broken bolt extractor kit. This kit has been released to assist in removal of the remaining bolt segment(s). In some cases the remaining bolt segment will back out easily with a pick tool or a reverse twist drill bit.
- The Kent Moore extractor kit includes one 5/32-inch reverse twist drill, one double-ended drill pilot insert (insuring straight drilling), drill pilot inserts for larger diameter head or main cap bolts. A bolt extraction EZ Out, an M11 x 2 bottoming tap for the head bolts (to chase threads after removal) and am M10 x 1.5 bottoming tap to clean main bolt threads.
Never re-use any TTY cylinder head or main cap bolt. Utilize a thread chaser tool followed by cleaning with dry compressed air to ensure clean female threads. Bolts that creak and snap while tightening will fail due to excessive torque caused by threads that are contaminated with debris, antifreeze or oil. Trace amounts of oil or antifreeze can cause this. In extreme cases the threads may require additional cleaning with a non-residue cleaner, followed by during with clean/dry compressed air.
