MTD
Front-Engine Lawn Tractor

Model #13BL78ST099 MTD tractor

Here are the diagrams and repair parts for MTD 13BL78ST099 tractor, as well as links to manuals and error code tables, if available.


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Showing 10 of 315 parts

Lawn & Garden Equipment Cotter Pin, 1/4- to 5/16-in

#25

Transmission Diagram

Lawn & garden equipment cotter pin, 1/4- to 5/16-in

Part #714-04040
This item is not returnable
$3.39 | 
34% OFF MSRP:$5.10

In Stock

Lawn Tractor Blade Drive Belt, 1/2 x 103-1/16-in

#55

Mower deck/spindle pulley Diagram

Lawn tractor blade drive belt, 1/2 x 103-1/16-in

Part #954-04219

Get free shipping with Automatic Reorder

$41.26

In Stock

Lawn & Garden Equipment Lock Nut, 5/16-18

#19

Transmission Diagram

Lawn & garden equipment lock nut, 5/16-18

Part #712-04063
This item is not returnable
$3.03 | 
24% OFF MSRP:$4.00

In Stock

Lawn Tractor Blade Engagement Cable

#22

Battery/frame Diagram

$59.07 | 
39% OFF MSRP:$97.00

In Stock

Lawn & Garden Equipment Hex Flange Nut

#20

Mower deck/spindle pulley Diagram

Lawn & garden equipment hex flange nut

Part #712-0417A
This item is not returnable
$4.79

In Stock

Lawn Tractor Steering Sector Gear

#1

Steering Diagram

$22.66

In Stock

Lawn Tractor Flange Nut

#76

Transmission Diagram

Lawn tractor flange nut

Part #712-04065
This item is not returnable
$2.68 | 
33% OFF MSRP:$4.00

In Stock

Lawn Tractor Bearing

#16

Steering Diagram

Lawn tractor bearing

Part #941-04124
This item is not returnable
$4.09

In Stock

Lawn Tractor Gauge Wheel

#32

Mower deck/spindle pulley Diagram

Lawn tractor gauge wheel

Part #734-04155
$16.27

In Stock

Lawn Tractor Mandrel and Pulley Assembly

#1

Mower deck/spindle pulley Diagram

$119.68

In Stock

Symptoms common to all riding mowers & tractors

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

Main causes: worn or broken ground drive belt, bad seat switch, transaxle freewheel control engaged, transaxle failure, dirty carburetor
Main causes: damaged cutting blade, worn deck pulley, damaged mandrel pulley, loose fasteners on mower deck components
Main causes: engine overfilled with oil, leaky head gasket or sump gasket, damaged carburetor seals, cracked fuel pump, broken fuel line
Main causes: punctured tire or inner tube, leaky valve stem, damaged wheel rim
Main causes: unlevel mower deck, dull or damaged cutting blades, worn mandrel pulleys, bent mower deck, engine needs tune up
Main causes: damaged tie rods, bent or worn wheel spindle, worn front axle, damaged sector gear assembly
Main causes: worn or broken blade belt, broken belt idler pulley, blade clutch cable failure, bad PTO switch, damaged mandrel pulleys
Main causes: shift lever needs adjustment, neutral control needs adjustment
Main causes: clogged carburetor, damaged flywheel key, dirty spark plug, stale fuel, improper valve lash, engine needs a tune up

Repair guides common to all riding mowers & tractors

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

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 replace it.

Repair difficulty
Time required
 30 minutes or less
January 1, 2015
By Lyle Weischwill
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.

Repair difficulty
Time required
 60 minutes or less
January 1, 2015
By Lyle Weischwill
How to replace a riding lawn mower blade

If a blade on your mower is dull or bent, replace it following the steps in this repair guide.

Repair difficulty
Time required
 30 minutes or less

Articles and videos common to all 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.

May 1, 2017

Riding lawn mower engine spins but won't start video

By Sears PartsDirect staff

Troubleshoot fuel, spark and compression issues.

June 1, 2016

How to mow a lawn for healthier grass

By Erin Hynes

How often and tall you mow your lawn has a big impact on its health. Check out these 3 rules.

March 1, 2016

How to change the Smart Switch Ignition password on a lawn tractor video

By Sears PartsDirect staff

See how to unlock the factory default start code so you can set your own passcode.