Stihl MM55 Gearbox Issues: Typical Issues, Symptoms, and Straightforward Remedies

What is the most typical issue with the transmission on a Stihl MM55? The most prevalent issue with the Stihl mm55 gearbox is a whining noise. That’s something every user can agree on.

There are a number of potential causes of the noise, including overheating, improper cooling, and poor construction.

Along with the whining noise, there are a number of other gearbox issues that might arise while using the Stihl MM55.

Here, we’ll zero in on five specific issues with the Stihl MM55 that really get under your skin. You’ll be able to zero in on the root of the problem quickly if you know what signs to look for.

Read this post thoroughly for the full set of instructions on fixing mm55 gearbox issues.

Difficulties with the Stihl MM55 Gearbox

stihl mm55 gearbox problems

Yard Boss users are no strangers to headaches caused by the Stihl MM55 gearbox.

In this table, we’ll introduce the five most common problems with the Stihl MM55 gearbox and provide quick fixes.

We shall go into greater detail about the symptoms and their root causes after the table.

Loss of transmission fluidRepair the leaking gas tank or get a new one.
Slow responseTake care to fuel your vehicle with clean, adequate supplies.
Whining noiseLessen the burden
Burning smellStay away from a gasoline deficit or a rusty machine.
Slipping gearFind the cause of fueling or solenoid/clutch/torque problems and fix them.

1. The Transmission Fluid Is Leaking

Tools like the Stihl MM55 gearbox are prone to transmission fluid leaks for a variety of reasons. From either the storage tank or the tube, the transmission fluid can be accessed.

  1. Symptoms
  2. Cogs turning
  3. Weird noises are emanating
  4. Turn off the speed booster
  5. A Weird Shaking Has Gone On
  6. Wet and muddy weather

If you notice any of these issues when operating your Stihl MM55, it’s quite likely that your transmission fluid is leaking.


The case of leaking transmission fluid has a few causes. These are the most common explanations.

  1. A leaky transmission is the result of a broken or fractured gasket in the transmission.
  2. In order to improve your speed, you need to decree the torque, which is why it’s important to damage the torque converter. Torque converter failure causes transmission fluid to spill.
  3. Leakage from a cracked fluid line occurs when the transmission fluid pipe is compromised.
  4. Most of the time, the problem arises because the knob was left slack, which lets transmission fluid leak.


In addition to turning the knob, we recommend repairing the gasket, transmission tubes, and torque converter if they are broken.

2. a sluggish reaction

The Stihl mm55 gearbox has a secondary issue of being slow to respond. The reaction time suffers when the Stihl MM55 gear head is not working properly.


  1. You can’t just make yourself go faster.
  2. There were issues with the acceleration.
  3. It’s a slow process to change gears.


The logic for this is crystal evident. The poor response of the Stihl MM55 gearbox can be attributed to the aforementioned fuel issue.

  1. The delayed reaction issue occurs when gasoline for the Stihl MM55 is not clean and filtered.
  2. Lack of fuel is the primary hindrance to a rapid rate of gear cutting. You will notice a decrease in gear response when your tank is low on gas.


Stihl MM55 is fueled by a 50/50 blend of gasoline and Stihl two-stroke oil. Ethanol content in the gas must not exceed 10%.

Always make sure you have enough fuel.

Read: Stihl ms 661 problems with Symptoms, Reasons, and Solution

3. A whimpering sound

This is by far the most popular application among users. The gearbox of the Stihl MM55 is notoriously loud and whiny, which is a common source of customer dissatisfaction.


  1. Strange or unpleasant noises coming from the device.
  2. We frequently experience eerie vibrations.
  3. There was a crackling noise as I changed gears.


The irritating whining sound has its roots in the production process. For instance;

  1. The whining noises can be caused by flaws in the design of the Stihl MM55 gearbox.
  2. Noise can be produced if the Stihl MM55 is forced to deliver a load that is too great for it to sustain.
  3. When the gasoline gauge is dangerously low, the noise can also appear. It’s telling you that the gas tank is becoming low.


It’s important to get the right one, one that isn’t broken. As much as you may want to help, refrain from placing an excessive amount of weight on it.

4. Scent of Fire

The Stihl MM55 gearbox has a burning odor, which is a major indicator of a malfunctioning fuel gearbox.


  1. When you start up the Stihl MM55, it emits a foul odor.
  2. During operation, smoke may be seen rising from the machine.
  3. A smoky odor can indicate fuel is leaking.
  4. The gearbox’s poor physical state


When your gearbox emits a burning odor, it may be due to issues with the fuel or the gearbox’s physical condition.

  1. Using Inadequate Oil: Running the Stihl MM55 with insufficient oil causes incomplete compassion, which in turn creates a burning smell problem.
  2. Misusing Contaminated Oil: It’s not just the quantity that matters, but also the quality of the fuel. The smell of burning might be detected if impure oil is used to produce energy.
  3. Old gearboxes are notorious for producing a burning odor due to their poor physical condition. An unpleasant burning odor is often given off by gearboxes older than five years.


Put an end to utilizing fuel with poor purity and quantity. And if you’ve had your Stihl MM55 for more than five years, it’s time to get a new one.

5. Gears that slip

When you’re having trouble shifting gears, you say that you’re “slipping gears.” Changing gears is a jerky process.


  1. The tines on my Stihl MM55 are frozen.
  2. Inconvenient during the gear shift.
  3. When you go to switch gears, a peculiar noise can be heard.
  4. Disappointing performance while changing gears.


Transmission experts advise using a 50:1 ratio of fuel to Stihl 2-stroke oil in your Stihl MM55.

In the event of a damaged gearbox, it must be replaced promptly.

Also, this video could be right up your alley!


Do you know what kind of gas the Stihl MM55 takes?

The fuel for the Stihl MM55 is a combination of regular gasoline and Stihl two-stroke oil.

To what extent does one need to pull the recoil cord before starting a Stihl MM55?

If you want to use the throttle after filling up the tank, you need to unlock the trigger first.
And keep them there until you’re able to make the switch back to the original course. The Stihl MM55 is now in your capable hands.

How much oil should I use in my Stihl Tiller?

With a 50:1 oil ratio, Stihl tillers can be fueled with a mixture of 50% gasoline and 1% Stihl two-stroke oil.


We should be aware of the potential issues with any given tool before committing to its use.

Two strong explanations underpin this reality. There are two ways to deal with stress: either avoiding it altogether or working through it quickly and effectively.

Because of this, the article about the issue with the gearbox on the Stihl MM55 is essential reading for anyone who owns or plans to buy one of these power tools.

We anticipate that once you have this data, you will be able to quickly pinpoint the source of the issues and devote less time and energy to resolving them.