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Hard, Slow, or No Start & Kickback During Crank on Some GM Vehicles
October, 2003
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Part # 6416, 6449, 6483, 6485
One or more of the following conditions may exist:
- Backfire or kickback during crank/start
- No start or slow or hard start/crank
- Grinding or unusual noises during starting/cranking
- Cracked or broken engine block at the starter boss
- Broken starter drive housing
- Broken starter ring gear on flywheel
- Any combination of the above
A condition may exist that allows the crankshift position sensor to command up to 50 extra degrees of spark advance during engine cranking only. This in turn exposes the engine to higher-than-normal cylinder pressures, which may result in an inoperative condition to the starter drive housing, the engine flywheel starter ring gear or the engine block at the outside edge of the starter boss.
To correct this, first inspect for a stored powertrain DTC P0338.
This DTC will not illuminate the "Service Engine Soon" light. If this code is stored, the crankshaft position sensor, P/N 10456607, must be replaced and the remaining components must be inspected for damage (engine block at the starter boss, the starter drive housing and the engine flywheel starter ring gear).
Notice: When DTC P0338 is set, failure to replace the crankshaft position sensor could result in repeated inoperative conditions of the starter or flywheel.
Important: Some flywheel wear is normal; broken or missing teeth and/ or cracks are not.
Source: Underhood Magazine Courtesy of AllData