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Common Mercury Outboard Shifting Problems – Easy To Handle

The shifting problems in the boat gears have become a common issue. However, it doesn’t get addressed as often.

So, the users face difficulty in finding solutions.

Are you eager to know about the common Mercury Outboard shifting problems?

The most common problems are the stiffness of the gear. This makes it hard for you to shift the gear forward.

Sometimes, the shifter in the tiller gets stuck in the forward gear.

Another problem is the outboard may get stuck in the gear whether the gear is in neutral or forward.

As you shift the gear, it also makes steady clanky noises sometimes.

But the good news is, all these problems have solutions. You can solve these issues by yourself.

If you want to know more, then you gotta read along!

How do Gear Shifts work on Mercury Outboards?

Mercury Outboard Shifting Problems

Gear shifts on Mercury outboards work by engaging and disengaging the propeller from the engine.

This is done by a lever on the side of the engine, which is connected to a cable that runs to the propeller.

When the lever is in the engaged position, the cable is tight, and the propeller is spinning.

When the lever is in the disengaged position, the cable is slack, and the propeller is not spinning.

To shift gears, first push the lever into the disengaged position.

Then move it to the desired gear position. The engine will automatically adjust to the new gear ratio.

There are two types of gear shifts on Mercury outboards: mechanical and electronic.

Mechanical gear shifts use a cable to physically connect the engine to the transmission.

The cable runs from the shifter handle on the boat to the transmission.

As you move the handle, the cable pulls or releases on a series of gears inside the transmission, engaging or disengaging them as needed.

Electronic gear shifts use sensors and actuators instead of a physical cable.

Sensors detect the position of the shifter handle and send a signal to an electronic control module (ECM).

The ECM then activates or deactivates various actuators inside the transmission to engage or disengage the gears.

4 Common Shifting Problems With Mercury Outboard

Shifting Problems With Mercury Outboard

The shift shaft alignment in the Mercury outboard is very crucial. If this alignment is in its place, half of the outboard problems disappear.

However, the frequently faced problems seem very similar to each other. Most of them are related to stiff gears which lead to difficulty in shifting.

However, even if the problems seem similar, the solution for each of them is different. So, let us look at the problems and their solutions in-depth now!

Problem 1: Gear Is Too Stiff to Shift Forward

The gear may get so stiff for 3 reasons. It could be due to tied wires to the cable. Internal rusting in the forward cable may also cause this. Stiff prop during shifting may also be the cause.

This scenario arises when your boat engine is off and is on the trailer. You can easily shift the gear in reverse. And then you can again reverse the throttle to neutral. But, it becomes barely usable while shifting the gear forward.

The stiffness would not persist when you press only the throttle button on the control box.


These problems may arise due to three reasons. So you need to check for three things. Firstly check if any wires are tied to control cables. So, you need to check for it. See if the cables can freely move for a minimum of 2 to 3ft after they leave the box. If they are tied tightly, they won’t be able to do this.

So, you just simply have to loosen it in that case.

If the cable seems fine, check for internal rusting in the forward cable. You need to know how to install boat engine control cables. This is because the cables need to be replaced.

Besides that, if internal rusting occurs, you need to oil it. To do that, make sure you’re using good-quality oils.

If the above two factors seem alright, you need to do this last thing. You have to just spin the prop and try to shift at that instant. This method works a lot of times. Also, make sure that you have the finest prop for Mercury 115 installed.

Problem 2: Shifter In Tiller Handle Stuck In The Forward Gear

The shifter in the tiller handle sometimes may just get stuck in the forward gear. It won’t move to the neutral gear. Nor would it move to the reverse gear.

This is due to the swelling of the plastic material of the lever.


There are loads of tiller motors that have binding shift linkage. Lubrication cannot really help here. The plastic material of the lever is connected to the shift rod of the lower unit.

This plastic material gets swollen and binds and causes the stiffness problem.

To solve this, you can do two things. You can either replace the shifting arm. Or you could grind or sand down the swollen part until it properly fits.

Problem 3: Outboard Stuck In Gear

Sometimes, the outboard may just be stuck in gear. It could be due to 3 reasons.

Firstly it could be due to impurity in the gear oil. Improper clamping between the lower and upper outboard could be one reason.

A jam between the link in the shift rod and shift lever can also cause this. And this issue would persist whether you have the lever in neutral or in forward.


utboard Stuck In Gear

Firstly, you need to check the gear oil for any sort of impurity like water. If there is, then you need to change the gear oil.

Is the problem in your gear more complex than that so the oil change did not help? Then try this.

Remove the rubber plug that is on the leg situated above the joint along with the gear case. Look for movement in the shift rod as you run the shift lever of the gear. Check if there is proper clamping between the lower section and the upper one.

Is the shift rod not moving? Then, look for a jam between the link in the shift rod and the shift lever.

This would become visible after the small plate held by two bolts is removed. If you find a jam in there, you can remove it by cleaning it with a cotton cloth and lubrication.

Problem 4: Steady Clanking Sound While Shifting Gears

Sometimes, whenever you shift the gears, there’ll be clanking noises. The noise may persist steadily throughout unless you check it. Many times, we overlook this problem. But we should not as this issue is a sign of a bad outboard.


Whenever this problem arises, check your gears and pinions. Broken parts in either of the gear or pinion would give rise to this issue. Usually, the parts that get broken are the lugs on the gear face or the clutch lugs. So, whichever has lost its tooth, that one should be replaced.

Now, these are all the problems that people frequently face. But, following the solutions can make things easier. Besides that, always use the marine fuel line that is the best. This would maintain the overall good health of your boat.


How do I adjust my outboard shift cable?

The adjuster jam nut on the throttle cable needs to be loosened with wrenches. Then the adjuster needs to be extended or contracted. This has to be done in accordance with moving the throttle in an idle position.

How do I know if my lower unit is bad?

Issues in operating shifting reflect a bad lower unit. Besides that, if water gets inside the gear lube or clunking sounds during the shifting of the gears also create this issue.

How do you adjust a Mercury outboard shift cable?

The shift cable end needs to be aligned with the center mark. Then the shift cable has to be placed on the end guide on top of the anchor pin.

The cable barrel needs to be adjusted to help it slip freely. The shift cable then has to be secured with the retainer of the shift cable.

Wrapping Up

Now that you know all the solutions, Mercury Outboard would be easier to handle. So, you do not have to stress too much about the Mercury outboard shifting problems.

Let us know if these solutions have helped you. Best of luck!

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