5 Common Cub Cadet RZT 50 Transmission Problems & Solutions

Cub Cadet RZT 50 is a zero-turn mower with a hydrostatic transmission system. It means the power is transferred from the engine to the wheels through fluids. As a result, there is no clutch in the hydrostatic transmission. With a much simpler transmission system, problems are also much less than with mechanical transmission systems, but they exist.

So, what are the Cub Cadet RZT 50 transmission problems? Low fluid level is the main problem in Cub Cadet RZT 50 transmission. Besides, clogged fuel lines or air filters leaked fuel lines, and worn belts or pulleys are some of the common problems in Cub Cadet RZT 50.

This guide will take you through the reasons behind these problems and help you find out their solutions. Let’s get started.

Common Transmission Problems and Their Solutions

Before diving into the details, here is a quick overview of the problems with Cub Cadet RZT 50 transmission with the solutions.

Low fluid levelsCheck the fluid level and top it up. Also, check for leaks.
Clogged fuel lines and air filtersClean fuel lines regularly. Replace the air filter.
Air in the fluid pumpPurge the transmission system.
Leaked fuel system componentsCheck fuel system components for leaks and fix them.
Worn belts or pulleys Check the belts or pulleys and replace them.

Let’s check out the problems and their possible solutions one by one. 

1. Low Fluid Levels

The performance of the hydrostatic transmission system is dependent on the fluid. It propagates the power from the engine to the wheels, so the fluid should be at an optimal level at all times. 

If the fluid level is low, the transmission won’t transfer the power as expected. So, you might feel the power delivery being sluggish or see the mower stall.


  • You need to check the fluid level using an oil level gauge. If the fluid level is repeatedly going low, you should check the system for any leaks. After you fix the leaks, you can top up the fluid.
  • Take the fluid suggested by the manufacturer and fill the fluid reservoir until it reaches the full line marked on the side of the tank.
  • If the fluid is much darker in color than it should be, you should replace the fluid. Take the oil filter and vent cap off to drain the fluid. Then, refill the reservoir with new fluid. 

You can watch this video to learn how to change the transmission oil on a zero-turn lawn mower. 


  • Consider changing the fluid once the mower has run for 1,000 hours.

2. Clogged Fuel Lines and Air Filters

If you use low-quality fuel in your Cub Cadet RZT 50 mower, the debris in the fuel can be deposited inside the fuel line. Over time, they will clog the line, and the fuel delivery will be disrupted. 

Aside from using low-quality fuel, the fuel line and the air filter can be clogged over time due to the surroundings. When the fuel supply is hampered, it will affect the whole system, including the transmission. Dirty air filters can cause the same problem.


  • The first step is to check the air filter. If it is slightly dirty, you can still use it after cleaning. 
  • But if the air filter is almost clogged, you need to replace it.
  • Flush the fuel line if clogged. 


  • Check the fuel line for clogs and clean it regularly.

3. Air in the Fluid Pump

A pump pushes the transmission fluid to circulate it throughout the system. But if there is air inside the pump, it can’t build up pressure to circulate the fluid. As a result, the transmission won’t deliver enough power. It mostly happens when you store the mower for longer, especially in winter.


  • Step 1: The rear end of the mower should be stable on a jack stand. And the parking brake should be set. Disengage the transmission by following the instructions manual.
  • Step 2: Turn the engine on and put the side lever in the neutral position. Release the brake.
  • Step 3: Put the side lever in the maximum forward position and keep it there for a few seconds.
  • Step 4: Put the side lever in the maximum reverse position and keep it there for a few seconds.
  • Step 5: Repeat steps 3 and 4 several times. The parking brake should be engaged again, and the engine should be turned off.
  • Step 6: Engage the transmission by following the manual. Then turn the engine on, and the mower should be ready to roll.


  • After storing the mower for a long time, always purge the system once.

4. Leaked Fuel System Components

Multiple components in the fuel system, such as fuel lines, carburetors, fuel tanks, fuel pumps, etc., can have leaks. These leaks are caused by regular wear. As a result, the performance of the transmission system will be affected. 

You can smell fuel around the mower or where you have used it. 


  • The first step in solving this problem is checking all the components for leaks. You can call an expert mechanic if you aren’t familiar with the system.
  • All the leaks should be fixed if they are small. But if the component is much older and has signs of wear everywhere, you should replace it.


  • If fuel lines are completely dry or there is any sign of cracks, you need to replace them.

5. Worn Belts or Pulleys

The driveshaft is connected to the transmission system in your Cub Cadet mower through the pulleys and belts. Over time, these belts or pulleys can get worn out. Sometimes, they might snap off if you don’t check them regularly. In such cases, the transmission will stop working.



  • Check the belts or pulleys after every 500 hours of use.

Final Words

The working principle of hydrostatic transmission in an RZT 50 is quite simple. So the problems are easier to identify and fix. We discussed 5 common Cub Cadet RZT 50 transmission problems and showed their solutions.

With a little knowledge of the mechanism and the step-by-step guide provided here, you can address these problems quickly and solve them on your own. And don’t forget to maintain the transmission system regularly to get the maximum performance out of it.

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