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Extracting broken exhaust manifold bolts on a Cummins ISX or ISX15 engine in-frame? Follow this step-by-step professional workshop procedure to mount the M20195 alignment plate, insert hardened drill bushings, drill the centered pilot core, step-drill the stud shell, and chase original threads cleanly without pulling the cylinder head off the block.

Why Freehand Drilling & Easy-Outs Destroy Cummins ISX Cylinder Heads

On Cummins ISX and ISX15 heavy-duty diesel engines, exhaust manifold mounting bolts are anchored directly into threaded blind holes in the cast-iron cylinder head. Because exhaust manifolds constantly expand and contract across hundreds of thousands of miles, mounting bolts suffer extreme shear fatigue, frequently snapping off flush or below the cylinder head deck surface. Technicians who attempt to extract these broken studs using handheld right-angle drills or spiral easy-outs face disastrous repair consequences. Freehand drilling on a hard, jagged broken stud causes the drill bit to skate off-center into the softer cast-iron cylinder head deck. Drilling into the head wall destroys the original M12/M10 thread geometry and breaks through internal coolant passages, causing permanent cylinder head failure. Furthermore, driving a spiral easy-out into a seized stud expands the broken bolt threads tighter against the head wall, snapping the ultra-hard extractor bit inside the hole. An easy-out bit cannot be drilled out with standard bits, turning a simple stud replacement into an emergency head pull. Utilizing the 16-pound M20195 Guided Drilling Fixture eliminates these service disasters completely. By locking the heavy alignment plate directly to adjacent sound bolt holes on the cylinder head face, the tool holds hardened steel drill bushings perfectly concentric over the broken stud center. The bit drills straight down the neutral axis of the stud, relieving thread pressure so the broken core can be extracted smoothly while preserving 100% of the original factory head threads.

The 5-Step Cummins ISX Exhaust Stud Extraction Protocol

1. Remove Exhaust Manifold & Clean Deck Surface: Remove the exhaust manifold and wire-brush carbon scale from the cylinder head deck face around the broken stud location.
2. Mount M20195 Alignment Template Plate: Secure the M20195 template plate to the cylinder head deck using included mounting bolts in adjacent open, sound thread holes. Hand-tighten bolts to align the target fixture hole over the broken stud.
3. Insert Hardened Pilot Bushing & Drill Pilot Hole: Lock the small pilot drill bushing into the M20195 template hole. Using the included cobalt pilot bit, drill straight through the center of the broken stud to create a dead-center pilot channel.
4. Step-Drill Core with Large Bushing & Bit: Replace the pilot bushing with the larger step-drill bushing. Drill with the larger step bit to hollow out the broken stud shell down to the root diameter of the threads without touching the head threads.
5. Extract Stud Shell & Chase Factory Threads: Insert the extraction tool into the hollowed stud shell to back out the remaining metal, or use the included tap guide and tap to chase and clean original cast-iron threads. *Inspect threads and install a fresh OEM Cummins exhaust stud with anti-seize.*

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