Owner’s manual
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How much does it cost to replace a riding lawn mower engine?
For a Craftsman riding lawn tractor like model 917275042, a full engine replacement (parts plus labor) typically costs about $800 to $2,500 total. The biggest cost drivers are the engine itself, any required mounting or wiring changes, and 4 to 8 hours of shop labor.
Typical cost breakdown
Costs vary by engine brand, horsepower, and whether you replace related wear items at the same time.
- Engine assembly: $500 to $1,800
- Labor (shop time): $300 to $900 (often 4 to 8 hours)
- Extra parts and supplies: $25 to $250 (fuel line, clamps, belts, hardware, oil)
- Pickup/delivery (if used): $0 to $150
| Scenario | What’s included | Typical total cost |
|---|---|---|
| DIY swap | Engine + your time | $500 to $1,900 |
| Shop replacement | Engine + labor | $800 to $2,500 |
| “While we’re in there” | Engine + belt/pulley/hardware refresh | $950 to $2,800 |
What can increase the price
These are common add-ons we see during engine swaps on riding mowers and tractors:
- Damaged or corroded wiring that needs repair (ignition circuit, charging circuit)
- Worn deck-drive components (for example a seized idler pulley)
- Safety interlock issues that must be corrected before safe operation
- Fuel system cleanup after old fuel storage (tank, stem, lines)
- Hardware replacement when fasteners are stripped or rusted
Parts that are commonly replaced during related repairs
If your “engine replacement” estimate includes fixing no-start or PTO issues, these parts on this model are often involved:
- Switch.pto 582107601 (PTO engagement problems)
- Molded ignition key 532140403 (lost or damaged key)
- Lawn tractor ignition harness 532170238 (intermittent start or ignition wiring damage)
Why it matters
A new engine can cost close to the value of an older tractor, so it helps to compare the total installed price against the mower’s overall condition (deck, transaxle, steering, and electrical). For model-specific operating and safety checks after repairs, use the owner's manual.
Last updated: February 2026
Is it worth replacing a lawn mower engine?
Yes, replacing the engine on your Craftsman lawn tractor model 917275042 is worth it when the tractor’s deck, steering, and drive system are still solid and the total engine-swap cost stays well below the price of a comparable new rider. If multiple major systems are worn, replacement usually makes more sense.
Quick decision checklist
- The mower deck is straight (no major rust-through or cracks) and still cuts evenly.
- The transaxle drives smoothly forward and reverse (no slipping or whining).
- Steering and front axle feel tight (no severe wobble or wandering).
- You can still get common wear parts like belts, pulleys, and switches.
- The engine failure is isolated (thrown rod, no compression, seized crank) rather than a symptom of overall neglect.
Cost and effort: what to compare
Engine swaps on riding mowers are most cost-effective when you are reusing the existing fuel system, wiring, throttle/choke controls, and muffler routing with minimal modifications.
| Compare | Replace engine | Replace tractor |
|---|---|---|
| Upfront cost | Often lower if the rest is in good shape | Higher, but includes everything new |
| Downtime | 1 weekend to several weekends | Usually immediate once purchased |
| Reliability | High if the chassis and drive are healthy | Highest overall |
| Skill/tools | Moderate to high DIY | Low |
Why condition matters (and what our manual emphasizes)
Your tractor’s long-term value depends on maintenance and safety checks. The owner's manual calls out routine items like checking for loose fasteners, keeping the machine clear of debris, inspecting belts, and servicing the battery and engine oil. If those basics have been kept up, an engine replacement tends to pay off.
When an engine replacement is the better choice
Replace the engine when:
- The tractor is generally under about 8 years of typical homeowner use.
- The deck and frame are structurally sound.
- You mainly need dependable mowing, not a full upgrade.
When replacing the tractor is the better choice
Replace the tractor when:
- The deck is damaged or the cut quality is poor even after leveling and blade service.
- The drive system is failing (belt issues plus transaxle problems).
- Electrical problems are widespread (interlock switches, wiring, charging issues).
Related parts that often come up during repairs
If you are troubleshooting “no crank” or intermittent starting before committing to an engine, common items include the ignition key and PTO switch, such as the molded ignition key 532140403 and switch.pto 582107601.
Last updated: February 2026
What engine does Craftsman riding mower use?
Craftsman lawn tractor model 917275042 is a 23.0 HP, electric-start gasoline garden tractor (50-inch mower) per the owner's manual. This model uses a twin-cylinder engine configuration, which affects tune-up parts such as spark plugs, air filter, and fuel system components.
How to identify the exact engine make and model on 917275042
Use the engine’s ID tag, then match it to the engine section of the manual and parts diagrams.
- Lift the hood and look for an engine brand badge (commonly Kohler or Briggs & Stratton on tractors of this type).
- Find the engine ID label (often on the blower housing, valve cover area, or near the starter).
- Record the engine model, spec, and serial numbers exactly as shown.
- Confirm whether your engine is twin-cylinder by checking for two spark plug leads.
- Use 917275042 when ordering tractor-specific parts that mount to the engine (muffler, wiring, PTO clutch, etc.).
What the manual tells us about this tractor’s engine setup
The manual establishes the power class and configuration for model 917275042.
| Item | 917275042 (from manual) | Why it matters |
|---|---|---|
| Horsepower class | 23.0 HP | Guides engine family and capability |
| Starting | Electric start | Battery, starter, solenoid checks |
| Fuel | Gasoline | Fuel freshness and carburetion apply |
| Cylinders | Twin-cylinder | Correct spark plugs and ignition parts |
| Tractor/deck | Automatic, 50-inch mower | Higher load; correct belts and PTO operation |
Why it matters
Engine make and exact model determine the correct maintenance specs (oil type and capacity) and the right tune-up parts. Twin-cylinder engines typically use different ignition and fuel components than single-cylinder engines.
Related DIY help
If the starter spins the engine but it will not fire, follow the checks in riding lawn mower engine spins but wont start video.
Last updated: February 2026
What model number is the Craftsman 42 riding mower?
For the Craftsman front-engine lawn tractor on this page, the model number is 917275042. If you are asking about a different Craftsman 42-inch riding mower, the model number is found on the tractor’s ID label; use that exact number to match the correct parts and owner's manual.
Where to find the model number on the tractor
On most Craftsman riding mowers, the model number is printed on a product identification label. Common label locations include:
- Under the seat pan (lift the seat and look on the frame)
- On the rear fender or rear frame area
- Near the engine compartment on the frame rail
- Under the hood area on the chassis
Why the exact model number matters
Craftsman 42-inch decks were used across many tractor variations (different engines, transmissions, steering parts, and deck linkages). The correct model number ensures you get the right diagrams and parts list for items like:
- Ignition key and ignition harness
- PTO switch and mower deck engagement parts
- Steering shaft, drag link, and sector gear
- Mower deck idler pulley and mandrel components
Quick check: model number vs deck size
Deck size alone (42-inch) does not uniquely identify a tractor. Use this as a guide:
| Identifier | What it tells you | What it does not tell you |
|---|---|---|
| Model number (example: 917275042) | Exact tractor configuration and correct parts breakdown | Nothing; it is the primary identifier |
| Deck size (example: 42-inch) | Approximate cutting width | Exact belt routing, spindle style, or PTO setup |
| Engine HP | Power class | Correct chassis, steering, or deck parts |
Related parts commonly tied to “model number” lookups
If you are confirming you are on the right parts list for model 917275042, these parts are examples that appear for this tractor:
Why it matters: Entering the wrong model number can lead to ordering parts that fit a different chassis or deck design, even if the mower is still a Craftsman 42-inch rider.
Last updated: February 2026
