Craftsman 917378420 gas walk-behind lawn mower Parts

On a Craftsman gas walk-behind mower like model 917378420, the model number is typically printed on a decal or ID plate on the mower deck or rear housing. Once you find it, match the full number exactly so you get the right parts list and diagrams for your mower.

Where to look on a walk-behind mower

Check these common ID-plate locations first:

• Top of the mower deck near the engine (often by the recoil starter area)
• Rear of the deck near the bagger door or discharge opening
• Side of the deck near a rear wheel height adjuster
• Handle support brackets (left or right side)
• Under the grass bag area (remove the bag and look at the rear panel)

For model 917378420, the owner documentation identifies it as a 21-inch rear-discharge, power-propelled rotary mower; using the exact model number helps ensure the correct drive, wheel, and blade-related parts match your build. See the 917378420 owner's manual for model identification and parts ordering guidance.

What to write down (and why)

Record the information exactly as shown on the decal.

Item to record	Example	Why it matters
Model number	917378420	Selects the correct parts diagrams
Serial number	(varies)	Helps match production changes
Engine model	143.016708	Ensures correct engine parts like carburetor items

Tips to avoid ordering the wrong parts

• Copy the full model number, including any dots or dashes shown on the label
• Clean the decal gently (mild soap and water) so all digits are readable
• Use the mower model number for chassis parts (wheels, belts, controls)
• Use the engine model number for engine parts (carburetor, primer, ignition)
• If you are troubleshooting self-propel issues, confirm drive-wheel parts match your model (for example, the husqvarna lawn mower wheel dust cover 581840401 is a common drive-wheel area component on this platform)

Why it matters

Craftsman walk-behind mowers can look similar across years, but small changes in the drive system, wheel adjusters, and blade mounting hardware affect fit. Using the exact model number prevents mismatched belts, wheels, and control parts.

Last updated: February 2026

Common problems on the Craftsman 917378420 gas walk-behind lawn mower include no-start conditions (dirty air filter, stale fuel, spark plug issues), loss of power from airflow or deck buildup, and poor cut quality from a worn or loose blade or uneven wheel height. For model-specific maintenance intervals and adjustments, use the 917378420 owner's manual.

Most common symptoms and what usually causes them

• Won’t start: dirty air filter, out of fuel, stale fuel, water in fuel, spark plug wire off, bad spark plug
• Runs but lacks power: cutting too much grass, dirty air filter, grass and debris packed under the deck, walking speed too fast
• Poor cut or uneven cut: worn or bent blade, loose blade hardware, wheel heights set uneven, deck packed with clippings
• Hard to pull or sudden stop: blade dragging in heavy grass or debris under the deck (stop and clear safely)

Quick checks we recommend (fastest wins first)

1. Turn the engine off and disconnect the spark plug wire before touching the blade or underside.
2. Confirm fresh gasoline; drain and refill if fuel is old or contaminated.
3. Inspect and service the air filter (clean or replace as needed).
4. Check the blade area for packed grass and debris; clean the underside of the deck.
5. Verify the blade is tight and the blade adapter is not cracked or slipping.

Parts that commonly solve “cut” and “vibration” complaints

If the blade feels loose, the mower vibrates, or the blade won’t stay aligned, the blade mounting parts are prime suspects.

Symptom	Likely wear item	What it affects
Blade slips or won’t stay tight	Blade adapter	Blade alignment and drive from crankshaft
Excess vibration	Blade adapter or bent blade	Smooth operation and cut quality
Uneven cut	Wheel height settings	Cutting height consistency

Helpful model-matched part to check: lawn mower blade adapter 581547901.

Why it matters

Most “common problems” trace back to routine maintenance: clean airflow (air filter), clean fuel, and a clean deck. Keeping the blade secure and the deck clear improves cut quality, reduces strain on the engine, and helps prevent hard-start and power-loss complaints.

Last updated: February 2026

Craftsman model 917378420 identifies the mower platform, not a single “model year.” To find the build date, we use the date code or serial information on the mower’s ID label (typically on the deck or handle area) and confirm details with the 917378420 owner's manual.

How to find the manufacturing date on the mower

Look for the product ID label first; that label carries the information used to determine when your specific unit was built.

• Check the rear of the deck, near the engine mounting area, and the handle bracket area
• Clean off grass and oil so the full code is readable
• Write down every character (letters and numbers) exactly as shown
• Look for wording like serial, date, DOM, or a stamped code on a metal tag
• Use the identification and parts diagrams in the 917378420 owner's manual to confirm you are referencing the correct mower

What the manual confirms (model-specific)

The manual confirms the mower type and model designation so you can match the correct documentation before decoding the ID label.

Manual detail	What it shows for this mower	Why it matters
Mower model	917.378420	Confirms you have the correct Craftsman walk-behind mower platform
Mower type	21-inch rear-discharge, power-propelled rotary mower	Helps match deck and drive-related parts
Engine info	Engine is listed separately in the manual’s engine section	Use the mower ID label first for dating; engine numbers help only as a secondary reference

Why it matters

The build date helps ensure parts compatibility when there are running changes during production (drive system hardware, wheels, cables, and belts). For example, if you are diagnosing self-propel issues while identifying the unit, the lawn mower wont move troubleshooting video motion drive failure helps narrow down common drive failures.

Last updated: February 2026