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Craftsman
Riding Mowers & Tractors

Model # 3904 Official Craftsman lawn tractor

Here are the diagrams and repair parts for Official Craftsman 3904 lawn tractor, as well as links to manuals and error code tables, if available.

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For DIY troubleshooting advice and repair guides, visit our repair help section.

Model diagram and schematic

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ALL PARTS
Showing 10 of 758 parts  |
Spring 66071-5422-0
#60

Bonnet - hood diagram

Spring

Part #66071-5422-0

The manufacturer no longer makes this part, and there's no substitute part

Bolt 01754-5085-0
#240

Crankcase - cylinder head diagram

Bolt

Part #01754-5085-0

The manufacturer no longer makes this part, and there's no substitute part

Lawn Tractor Bolt 13961-2214-0
#60

Piston - crankshaft diagram

Lawn tractor bolt

Part #13961-2214-0

The manufacturer no longer makes this part, and there's no substitute part

Axle 66071-1711-0
#10

Rear axle diagram

Axle

Part #66071-1711-0

The manufacturer no longer makes this part, and there's no substitute part

Lawn Mower Cover 66071-5214-0
#50

Fender diagram

Lawn mower cover

Part #66071-5214-0

The manufacturer no longer makes this part, and there's no substitute part

Pipe Inlet 66071-5813-0
#100

Air cleaner diagram

Pipe inlet

Part #66071-5813-0

The manufacturer no longer makes this part, and there's no substitute part

Piston Ring Assembly 12181-2105-0
#20

Piston - crankshaft diagram

Piston ring assembly

Part #12181-2105-0

The manufacturer no longer makes this part, and there's no substitute part

Belt Retainer 66082-4355-0
#220

Tension arm diagram

Belt retainer

Part #66082-4355-0

The manufacturer no longer makes this part, and there's no substitute part

Washer 66021-5528-0
Washer

Part #66021-5528-0

The manufacturer no longer makes this part, and there's no substitute part

Tension Arm Support 66071-5162-0
#110

Tension pulley diagram

Tension arm support

Part #66071-5162-0

The manufacturer no longer makes this part, and there's no substitute part

Most common symptoms to help you fix your riding mowers & tractors

Choose a symptom to see related riding mower and lawn tractor repairs.

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How do I charge a dead battery on my riding mower?

Main causes: faulty battery, bad alternator…

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Why does my riding mower deck vibrate?

Main causes: damaged cutting blade, worn deck pulley, damaged mandrel pulley, loose fasteners on mower deck components…

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Why is the steering loose on my riding mower?

Main causes: damaged tie rods, bent or worn wheel spindle, worn front axle, damaged sector gear assembly…

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Why won't my riding mower cut grass?

Main causes: worn or broken blade belt, broken belt idler pulley, blade clutch cable failure, bad PTO switch, damaged ma…

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How do I fix a flat tire on my riding mower?

Main causes: punctured tire or inner tube, leaky valve stem, damaged wheel rim…

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Why is my riding mower leaking oil or gas?

Main causes: engine overfilled with oil, leaky head gasket or sump gasket, damaged carburetor seals, cracked fuel pump, …

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Why does my riding mower run rough or misfire?

Main causes: clogged carburetor, damaged flywheel key, dirty spark plug, stale fuel, improper valve lash, engine needs a…

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Why does my riding mower creep in neutral?

Main causes: shift lever needs adjustment, neutral control needs adjustment…

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Why won't my riding mower move?

Main causes: worn or broken ground drive belt, bad seat switch, transaxle freewheel control engaged, transaxle failure, …

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Most common repair guides to help fix your riding mowers & tractors

These step-by-step repair guides will help you safely fix what’s broken on your riding mower or lawn tractor.

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How to replace the starter motor on a riding lawn mower

How to replace the starter motor on a riding lawn mower

If you hear the solenoid click but don’t hear the starter motor spin when you turn the key, follow these steps to replac…

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Repair difficulty
Time required
 30 minutes or less
How to rebuild a riding lawn mower carburetor

How to rebuild a riding lawn mower carburetor

Get your sputtering carburetor running smoothly in 60 minutes.…

Read more
Repair difficulty
Time required
 60 minutes or less
How to replace a riding lawn mower rear tire

How to replace a riding lawn mower rear tire

Your mower can’t run on a damaged rear tire. Here’s how to install a new one.…

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Repair difficulty
Time required
 60 minutes or less

Effective articles & videos to help repair your riding mowers & tractors

Use the advice and tips in these articles and videos to get the most out of your riding mower or lawn tractor.

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How to enjoy all the online benefits we offer on our Sears PartsDirect website

How to enjoy all the online benefits we offer on our Sears PartsDirect website

Learn about all the convenient features on our Sears PartsDirect website that make your parts purchases easier.…

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Top questions about Sears and Sears PartsDirect

Top questions about Sears and Sears PartsDirect

Get answers to frequently asked questions about Sears and Sears PartsDirect.…

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Riding lawn mower engine clicks but doesn't turn over video

Riding lawn mower engine clicks but doesn't turn over video

Check the starter solenoid, starter motor, wiring, battery and engine.…

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