Cub Cadet Challenger 750 Problems & How to Fix Them

Owning a tractor can make maintaining your property so much easier, allowing you to mow large areas, clear snow, and complete other chores and projects with less effort. The Cub Cadet Challenger 750 is a popular mid-sized tractor option, providing ample power and capability for most homeowners.

But what do you do when your dependable Challenger 750 suddenly starts having issues?

From engine trouble to electrical gremlins, there are several common problems that can affect the Challenger 750. Fortunately, many of these issues can be resolved with some basic mechanical skills and troubleshooting.

In this detailed guide, we’ll walk through the most frequent Cub Cadet Challenger 750 problems owners deal with. We’ll cover:

• Engine problems like overheating, won’t start issues, and loss of power
• Electrical gremlins causing instrument panel failures and dimming lights
• Transmission problems leading to slipping and loss of drive
• Steering component faults resulting in loose, wandering steering
• Suspension problems creating uneven mowing
• Quick fixes to get your tractor running again
• Preventative maintenance tips to avoid future breakdowns

Armed with the information in this guide, you’ll be prepared to diagnose and repair the most common Challenger 750 issues to keep your tractor in top operating condition. Let’s get started!

Common Kohler Engine Problems

The Cub Cadet Challenger 750 comes equipped with a robust 747cc Kohler engine that provides plenty of power and torque for all your tasks. But this workhorse engine can occasionally develop some problems that leave you sputtering instead of mowing.

Here are the most common Kohler engine issues on the Challenger 750 and how to get back up and running again.

Engine Overheating

Excessive engine heat is one of the most serious problems you can encounter. If left unchecked, overheating can lead to damaged cylinder heads, melted pistons, and blown head gaskets.

But with some basic troubleshooting, you can often identify the cause and prevent further damage. Here are the most common overheating causes and solutions:

• Clogged Radiator Screen – The radiator on the Challenger 750 sits low to the ground and is vulnerable to debris buildup. Check the radiator screen and fins for compacted grass clippings, dirt, and leaves. Use pressurized air or a garden hose to clean out any obstructions.
• Faulty Radiator Cap – Make sure the radiator cap seals properly and holds pressure. If not, replace it with a new OEM Kohler cap rated for the proper psi.
• Low Coolant Level – Check the coolant overflow reservoir and radiator fill neck. Top up with a 50/50 mix of coolant and distilled water if low. Look for any leaks or weepy hoses.
• Damaged Radiator Hoses – Inspect all coolant hoses for cracks, soft spots, and swelling that indicates a failing hose. Replace any suspect hoses immediately to avoid a blowout.
• Defective Water Pump – If coolant circulation is compromised, the engine will overheat. Check for leaking seals and adequate flow. Replace the water pump if faulty.
• Thermostat Stuck Closed – The thermostat should open once the engine reaches operating temperature. Replace it if you suspect the thermostat is stuck shut and not allowing coolant to circulate.

By methodically checking each component, you can usually resolve overheating issues before they cause serious engine damage. Just be sure to let the engine fully cool before carefully inspecting the cooling system.

Lack of Power Under Load

You go to engage the mower deck or dig into a pile of dirt with the loader, and suddenly the engine bogs down and lacks its normal giddy-up. What gives?

There are a few potential culprits when your Challenger 750 loses power:

• Clogged Air Filter – Check the air filter element and housing for excessive dirt buildup. Clean or replace the filter if it’s restricting airflow to the carburetor.
• Dirty Fuel Filters – Clogged fuel filters prevent proper fuel delivery. Replace the filters and inspect the tanks for debris and water that could re-clog them.
• Faulty Fuel Pump – Make sure fuel is reaching the carburetor. Verify operation of the low pressure and high pressure fuel pumps. Replace if faulty.
• Incorrect Governor Setting – The governor controls engine speed as loads change. Have a dealer adjust it to spec if the engine RPMs are dropping excessively under load.
• Carburetor Issues – Problems like stuck float valves and improperly adjusted mixtures affect performance. A carb rebuild or replacement may be needed if tuning attempts fail.
• Low Compression – Over time, worn rings and cylinder walls reduce compression. A leakdown test by your dealer can confirm if a rebuild is needed to restore power.

Don’t just live with a lackluster engine. Promptly troubleshoot performance issues to identify and resolve the root cause. You’ll get back to full power output before excess strain damages the engine.

Intermittent No Start Condition

One day your Challenger 750 starts up just fine, but the next time you hop in the seat it only cranks over sluggishly or not at all. What’s with the inconsistent starting?

Here are some likely culprits:

• Loose or Corroded Battery Cables – If your battery connections are compromised, power struggles to reach the starter. Check the terminals and cables for corrosion buildup and snug them up.
• Weak or Dead Battery – Using a multimeter, check the battery charge state and load test it. Recharge or replace the battery if it can no longer hold a full charge.
• Defective Safety Interlock Switches – Switches for the park brake, PTO, and operator’s seat must be engaged for the tractor to start. Replace faulty switches.
• Bad Starter Solenoid – Listen for a distinct click when the key is turned. No click indicates a failed solenoid. Replace it or the entire starter motor if needed.
• Damaged Starter Motor – If the solenoid clicks but the engine doesn’t crank, the motor itself has likely failed. Replacement starters are readily available.

Hard starting that only occurs occasionally is frustrating. By testing components in the starting system, you can isolate the specific cause and make repairs to get back on schedule.

Engine Runs Rough or Misfires

Is your Challenger 750 down on power and running unevenly? Fouled spark plugs, carburetor issues, and bad ignition coils can all cause sputtering and misfires.

Here’s how to pinpoint the culprit:

• Plugged Fuel Filters – Contaminated gas or debris can obstruct the fuel filters. Replace them and inspect the tanks.
• Faulty Ignition Coils – Use an ignition coil tester to check for cracks and winding failures. Replace defective coils.
• Spark Plug Fouling – Inspect the plugs for carbon buildup or other signs of misfiring. Re-gap or replace the plugs as needed.
• Carburetor Tuning – Make sure the float level, fuel mixture, and choke settings are adjusted properly. Rebuild or swap out the carb if tuning fails.
• Vacuum Leaks – Cracked hoses and loose fittings create lean conditions and instability. Inspect all connections and replace degraded hoses.
• Valve Clearance – Excessive clearance or leaky valves will make the engine run rough. Have a dealer check and adjust the lash.

Without smooth and consistent combustion, performance suffers. By isolating misfiring cylinders and components, you can restore proper engine operation.

Oil Leaks

It’s disheartening to find puddles of oil underneath your Challenger 750, not to mention the risk of low oil levels damaging the engine. But you can detect the source of most leaks by carefully inspecting the engine.

Here are some of the most common oil leak sources:

• Valve Cover Gasket – A dried out, cracked gasket allows oil to dribble down the side of the engine. Carefully clean and install a replacement gasket.
• Crankcase Breather – The breather can leak if clogged with sludge. Replace it and use the recommended weight oil.
• Oil Drain Plug – The drain plug washer can flatten out over time and leak. Replace the washer or install a new oil plug.
• Oil Filter Gasket – A loose filter or damaged rubber gasket causes leaks. Check the tightness and sealing surface.
• Timing Cover Gasket – Hardened gaskets on the front timing cover require replacement to stop leaks. Have your dealer reseal it.
• Rear Main Seal – The main crankshaft seal eventually hardens and leaks. This is a more involved repair best left to a professional.

With some diligence, you can trace most external oil leaks back to the source and make repairs to get your Challenger 750’s engine sealed up properly. Monitor fluid levels closely until leaks are fixed.

Overview of Kohler Engine Repairs

While the Kohler engine powering the Challenger 750 is generally durable, it can face common issues like overheating, oil leaks, hard starting, and loss of power. Thankfully, most engine problems can be repaired with basic tools and mechanical know-how. Just be sure to use OEM or equivalent quality replacement parts.

Following the manufacturer’s maintenance schedule goes a long way towards preventing major repairs down the road. But even well maintained engines eventually need rebuilt or replaced. If the repairs you need are beyond your technical skill or tools, don’t hesitate to rely on a trained small engine technician.

Electrical System Gremlins

In addition to engine problems, Cub Cadet Challenger 750 owners also report a variety of electrical issues ranging from annoying to dangerous.

Dim instrument panel lights. Sputtering starter motors. Dead batteries. Faulty wiring harness connections.

While electrical problems can be frustrating to diagnose, there are tried and true troubleshooting steps you can take to track down and repair the source.

Here are some of the most prevalent electrical problems on the Challenger 750 and their solutions:

Dim or Flickering Panel Lights

If your instrument panel lights start to lose brightness or flicker, the root cause is likely:

• Low Battery Charge – Using a multimeter or load tester, check the battery voltage and condition. Recharge or replace the battery if needed.
• Loose Battery Cables – Check for corrosion and tighten the battery terminal connections to ensure solid contact.
• Faulty Alternator – With the engine running, use a multimeter to test alternator output. Replace it if outside spec.
• Bad Grounds – Clean corrosion from all ground connections. Trace and repair any damaged ground wires.
• Blown Fuse – Inspect the fuse panel and replace any burnt out fuses. Address the root cause of the short or overload.
• Panel Wiring – Check for damaged wires and connectors leading to the instrument panel. Repair or replace bad connections.

With the lighting restored, monitoring critical gauges and alerts will no longer be an issue.

Weak Starter Motor Cranking

When the starter only turns over weakly or slowly cranks the engine, your starting system needs attention:

• Battery Connections – Loose or corroded battery cables prevent full current flow. Tighten terminals and clean any buildup.
• Low Battery Charge – Use a multimeter to check voltage. Charge the battery or replace it if defective.
• Bad Solenoid – Listen for the starter solenoid click when engaging. If no click, replace the solenoid.
• Brushes Worn – Inspect and replace excessively worn brushes in the starter motor if needed.
• Insufficient Motor Current – If brushes and connections check out, the motor itself is likely failing. Replace defective starter motor.
• Engine Seized – Starters fail to crank seized engines. Diagnose and repair the engine issue first.

Hard starting is frustrating. Methodically trace the voltage path from battery to starter to isolate and repair the component preventing robust cranking.

Dead Battery

There’s nothing more annoying than turning the key and getting no response as your battery fails to engage the starter.

While batteries gradually lose capacity over time, some common causes of premature battery death include:

• Short Circuit – Inspect wires for damage that could be draining and killing the battery. Repair any shorted wires.
• Corroded Terminals – Buildup on the battery post connectors interrupts current flow. Clean terminals thoroughly.
• Low Fluid Level – On accessible batteries, check cell levels and refill with distilled water as needed.
• Defective Alternator – If not charging properly, the alternator drains the battery. Test alternator output and replace if outside spec.
• Excessive Cranking – Extended cranking to start a faulty engine can kill the battery. Diagnose and repair the hard starting issue.
• Old Age – Batteries lose capacity after a few years. Check manufacture date codes and replace battery if over 5 years old.

Practice regular battery maintenance and promptly troubleshoot charging issues to maximize battery lifespan. Keep spare batteries on hand so a dead one doesn’t shut down your operation.

Blown Fuses

Popping fuses point to an underlying electrical issue that needs quick resolution. Some common causes include:

• Wire Damage – Fraying or pinched wires can create shorts and overload fuses. Inspect wiring and repair or replace.
• Loose Connections – If wiring connections vibrate loose, arcs and shorts blow fuses. Check terminals are secure.
• Incorrect Fuse Rating – Don’t install a higher rated fuse than specified or it may fail to protect the circuit.
• Faulty Components – Components like fuel pumps, electric clutches, and motors can internally short and blow fuses. Test circuits and replace damaged parts.
• Water Ingress – Moisture corrodes connectors and allows shorts. Seal any water entry points and dry out wiring harnesses.

When dealing with blown fuses, addressing the underlying cause is critical to prevent continued damage or electrical fire.

Overview of Electrical Repairs

The wiring, starters, alternators, and instruments on the Challenger 750 keep you running and aware of tractor health. But vibration, dirt, and moisture can corrupt even the most robust electrical components over time.

Pay attention to any gauge fluctuations, hard starting, or dimming lights as early indicators of issues. Methodically trace and test circuits to isolate and repair faults. Use dielectric grease on connections and seal out moisture.

While complex wiring schemas can be daunting, applying basic diagnostic steps allows you to pinpoint and fix most electrical gremlins. Tap into the amazing power of troubleshooting!

Transmission Slipping or Loss of Drive

The hydrostatic transmission on the Cub Cadet Challenger 750 provides smooth, infinitely variable speed control. But this complex transmission is also prone to occasional issues and failures.

Symptoms like loss of drive, slow acceleration, and inability to reach top speed usually stem from:

• Low Transmission Fluid – Check the fluid level and top up if needed. Look for leaks at gaskets and seals.
• Clogged Transmission Filter – Replace the filter to restore fluid flow and pressure.
• Damaged Charge Pump – This key pump builds pressure. Replace it if worn out or defective.
• Failed Drive Motor – The hydraulic motor loses power if damaged. Replace it to restore normal drive function.
• Worn Swashplate – Excessive wear allows slipping and loss of control. The swashplate requires replacement.
• Damaged Pistons or Cylinder Block – Leaking pistons and cylinders cause slippage and poor performance. Proper repair requires transmission overhaul or replacement.
• Broken Belts or Pulleys – The drive belt may fail or pulleys can seize up. Inspect both thoroughly.

Transmission issues lead to unpredictable and dangerous loss of vehicle control. Safely park the machine and thoroughly diagnose the specific failure before attempting to operate. Extensive hydrostatic transmission repairs often require the skills of an experienced technician. Seek prompt professional service to get your Challenger 750’s drive performance restored.

Steering Wobble and Shimmy

Loose steering components turn an otherwise pleasant drive into a white-knuckle ride. If your Challenger 750 starts to exhibit steering wander, shimmy, or wheel wobble, inspect the following wear points:

• Loose Steering Shaft – Check for excessive play indicating worn splines or loose U-joints. Tighten or replace components as needed.
• Damaged Steering Gearbox – Leaking seals and loose sector shafts require gearbox overhaul or replacement.
• Worn Tie Rod Ends – Inspect tie rod ends for looseness or cracking. Replace any that show excessive wear.
• Faulty Power Steering Valve – Malfunctioning valves cause power assist fluctuations and instability. Test and rebuild or replace if faulty.
• Loose Wheel Hubs – Check for bearing play and loose lug nuts. Replace damaged bearings and tighten lugs to spec.
• Bent Axles – Hitting obstacles can bend axle tubes and alter alignment. Remove and inspect front axle condition.
• Tire Wear – Excessively cupped or unevenly worn tires will induce vibration. Rotate or replace worn tires.

While steering systems have multiple wear points, methodically inspecting each component will help you zero in on the specific cause of wander or shimmy. Proper repairs restore a smooth, confident steering feel.

Uneven Cutting on Slopes

Maintaining a level deck is crucial for an even cut finish. But on hilly terrain the Challenger 750’s suspension can compress and throw off deck height. Here’s how to resolve uneven mowing:

• Adjust Rear Wheels – Ensure both wheels have the same number of shims to keep the deck level side-to-side.
• Check Tire Pressure – Keep all tires inflated to the recommended pressures. Low pressure allows more suspension sag.
• Inspect Mower Deck – Check the deck hangers and mounts for any cracks or loose fasteners that could affect its mowing height. Tighten hardware or replace damaged parts as needed.
• Install Suspension Lockout – Locking out the suspension prevents the deck from lowering on slopes. This is an easy add-on upgrade.
• Adjust Anti-Scalp Rollers – Position the rollers lower to reduce deck droop in the suspension’s downward travel. But don’t set too low as to create scalping.
• Alter Your Mowing Pattern – Mow up and down slopes rather than side-to-side to minimize the side-to-side suspension shift that alters cutting height.

Take the time to properly set up and adjust the Challenger 750’s suspension and mower deck so it maintains an even cut whether mowing the flats or a rolling landscape. Consistent cutting quality leaves your turf looking professionally manicured.

Preventative Maintenance is Key

The best way to avoid unexpected downtime due to Challenger 750 issues is following proactive maintenance procedures. Here are some key upkeep tasks that will keep your tractor running reliably:

• Regular Oil Changes – Replace engine oil and filter every 100 hours of operation as specified in the manual. Keep fluids fresh and engines wear minimally.
• Inspect Belts and Filters – Check engine and mower belts for cracking and replace air, fuel, oil, and transmission filters regularly.
• Lubricate Fittings – Use grease gun to lubricate all zerks every 25 hours to prevent binding and wear.
• Check Tire Pressures – Improper inflation causes uneven wear. Keep tires at recommended pressures.
• Sharpen Mower Blades – Sharpen and balance blades at least once per year or when cutting performance declines.
• Detail Clean Radiator – Use compressed air and water to thoroughly clean dust and debris off the radiator fins, screens, and A/C condenser.
• Check Wave Generator – Ensure wave generator underneath PTO deck moves freely to drive belts. Lubricate shaft yearly.
• Inspect Switch Contacts – Spray starter, PTO, and control switches with contact cleaner spray to prevent corrosion buildup.

Making scheduled maintenance second nature reduces downtime and costly repairs over your tractor’s lifetime. Follow the manual’s guidelines and your Challenger 750 will provide years of reliable service.

Conclusion

While the Cub Cadet Challenger 750 is powered by proven components, common issues can still occur with its engine, electrical system, transmission, and other parts over time. Fortunately, you can troubleshoot and repair most problems using basic tools and mechanical knowledge. Just be sure to use replacement parts that meet OEM specifications.

Stay ahead of issues by following the prescribed maintenance intervals and proactively inspecting components. Catch problems early before they lead to major failures. Don’t hesitate to tap into the expertise of small engine or transmission technicians for complex repairs or rebuilds.

With some attentive troubleshooting and skilled repair work, you can keep your Challenger 750 running smoothly for the long haul. Here’s to many more years of productive service from this trusty tractor!