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Gmc C3500 Engine Timing Crankshaft Gears

Gmc C3500 Engine timing crankshaft gears

Starting at $18.95, AutoBuffy stocks 2 engine timing crankshaft gears from Cloyes. The crankshaft gear is a precision-machined sprocket pressed onto the crankshaft nose that drives the timing chain or belt, synchronizing the crankshaft with the camshaft. A worn or damaged gear causes timing drift, leading to misfires, power loss, and potential engine damage.

Signs your Gmc C3500 needs a new engine timing crankshaft gear

  • Hard starting or extended cranking time as worn gear teeth allow timing chain slack that disrupts spark and fuel timing
  • Rough idle or persistent misfire codes (P0300–P0304 range) caused by inconsistent valve and ignition timing
  • Rattling or slapping noise from the front of the engine at startup, especially when cold, indicating a loose or skipping timing chain on a worn gear
  • Check Engine light with camshaft or crankshaft position correlation codes (P0016, P0017) pointing to timing chain and drive gear wear
  • Noticeable loss of power and fuel economy as valve timing drifts out of specification due to a worn or sheared gear keyway
  • Visible timing chain stretch confirmed at inspection, often caused by or accelerated by gear teeth worn flat or with rounded profiles

Which engine timing crankshaft gear should you buy for your Gmc C3500?

The main decision is matching the correct tooth count, bore diameter, and keyway specification for your engine — an incorrect gear will immediately throw off cam-to-crank timing. Material grade and whether the gear is sold as a standalone piece or as part of a timing kit are also important considerations, since replacing the gear alone while leaving a worn chain shortens the new gear's life significantly.

OE-Replacement Standalone Gear
Best for
Replacing only the crankshaft gear when the chain and camshaft gear are confirmed good
What you get
Exact OE tooth count, bore, and keyway; direct press-fit; typically sintered steel or cast iron matching factory spec
Timing Kit (Gear + Chain + Cam Gear)
Best for
High-mileage engines or any timing job where chain wear is present
What you get
All drive components replaced together; eliminates mismatched wear; better long-term value than piecemeal replacement
Performance / Billet Steel Gear
Best for
Modified engines, high-RPM builds, or applications prone to OE gear cracking
What you get
CNC-machined billet steel construction; tighter dimensional tolerances; resists deformation under high heat and load
Double-Roller Timing Set with Offset Key
Best for
Engines with camshaft timing adjustability needs (performance tuning)
What you get
Multi-position crankshaft gear with adjustable keyway slots; allows cam advance or retard; typically sold as a matched set

Engine timing crankshaft gears brands we stock for your Gmc C3500

Cloyes
2 options · from $18.95

Replacing an engine timing crankshaft gear on a Gmc C3500

Advanced⏱ 3–6 hoursHarmonic balancer puller and installer kitFront crankshaft seal driverBreaker bar or impact wrench for crankshaft boltTiming light or camshaft alignment tool set (engine-specific)Standard socket and wrench set

Replacing the crankshaft gear requires draining coolant if the water pump is timing-cover-mounted, removing the harmonic balancer, and pulling the front timing cover to expose the gear. The old gear must be pressed or carefully driven off the crankshaft snout without damaging the keyway, and the new gear pressed on until fully seated against the shoulder. Timing marks must be aligned precisely before reassembly, and a new front crankshaft seal and timing cover gasket should be installed while the cover is off.

Frequently asked questions

How much does it cost to replace engine timing crankshaft gears on a Gmc C3500?
The part itself starts at $18.95 on AutoBuffy. Total repair cost depends on whether you replace just the crankshaft gear or a full timing kit, and whether labor is involved. A shop timing job is labor-intensive since the front of the engine must be disassembled, so parts cost is typically a small fraction of the total bill.
Can I replace just the crankshaft gear without replacing the timing chain on my Gmc C3500?
Only if the chain and camshaft gear measure within spec. A worn chain paired with a new crankshaft gear accelerates wear on the fresh gear immediately. In most real-world cases, if the crankshaft gear is worn enough to cause symptoms, the chain and camshaft gear are due as well. Replacing all components together is the correct approach.
What causes a timing crankshaft gear to wear out prematurely on a Gmc C3500?
Infrequent oil changes are the leading cause — dirty or low oil starves the gear and chain of lubrication, accelerating tooth wear. Detonation, a stretched chain hammering against gear teeth, and overheating can also cause premature wear or cracking. Using the correct oil viscosity and change intervals dramatically extends gear life.
How do I know if the crankshaft gear keyway is damaged on my Gmc C3500?
A sheared or wallowed-out keyway causes the gear to slip on the crankshaft snout, immediately advancing or retarding cam timing by a significant degree. Symptoms are sudden, severe: hard no-start, extreme misfires, or the engine running as if timing is dramatically off. Inspection requires removing the harmonic balancer to examine the keyway and crankshaft snout directly.
Is replacing a timing crankshaft gear a DIY job on a Gmc C3500?
It is an advanced job. Accessing the crankshaft gear requires removing the harmonic balancer, front timing cover, and often other front-of-engine components. A harmonic balancer puller and installer are required — hammering the gear on risks crankshaft damage. Technicians experienced with timing system disassembly can complete it, but it is not recommended for first-time DIYers.
Will a worn timing crankshaft gear throw OBD-II codes on a Gmc C3500?
Yes. As the gear wears and timing drifts, the ECU detects the offset between crankshaft and camshaft position sensors and sets correlation fault codes, commonly P0016 or P0017. These codes do not always isolate the crankshaft gear specifically — a worn chain or camshaft gear produces identical codes — so physical inspection is necessary to confirm the root cause.

Shop engine timing crankshaft gears by year for the Gmc C3500

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