Repairing Boat Trim Stop: A Comprehensive Guide To Fixing Yours

The trim and tilt system is an essential feature of a boat's engine, allowing for the adjustment of the engine's angle and, consequently, the boat's running surface. This system is electrohydraulic and requires regular maintenance. One common issue with this system is a stuck trim, which can be caused by various factors, such as a blown fuse, issues with the hydraulic pressure line, or a faulty hydraulic pump or valve body assembly. Troubleshooting this issue involves identifying the root cause and taking appropriate corrective actions, such as replacing fuses or seeking professional repairs for more complex problems.

Check the battery and battery switch

To fix a trim stop on a boat, one of the first things you should do is check the battery and battery switch. Here's a detailed guide on what to look for:

First, locate the battery and battery switch. The battery is typically located in an easily accessible area of the boat, such as under a seat or in a dedicated battery compartment. The battery switch is usually labelled and may be marked with "1/2/BOTH" or "OFF/1/2/B".

Next, inspect the battery for any signs of damage or corrosion. Make sure the battery terminals are clean and free of any residue or build-up, as this can cause electrical resistance. Check the battery's charge level to ensure it is adequately charged. If the battery appears to be in good condition, move on to the next step.

Now, let's focus on the battery switch. The battery switch controls the flow of electrical power between multiple batteries on a boat. It allows you to select which battery is in use or being charged. Typically, there are two battery banks: the "start" battery bank, which is dedicated to starting the engine, and the "house" bank, which powers onboard appliances such as lights and electronics.

Examine the battery switch and ensure it is in the correct position. The "OFF" position should only be used when the boat is not in use, as it disconnects the alternator from charging the battery banks. The "Position 1" or "1" setting is usually assigned to the start battery, providing power to start the engine or charging it while the engine runs. The "Position 2" or "2" setting is typically for the house bank, powering appliances and charging the house bank through the alternator. The "ALL" or "BOTH" setting enables the use or charging of all batteries simultaneously, but be cautious as this can lead to depletion of all batteries.

If the battery switch is in the correct position and the batteries are charged, try operating the tilt and trim functions. If the engine fails to respond, there may be an issue with the electrical system or hydraulic pump, which will require further troubleshooting.

By following these steps, you can effectively check the battery and battery switch as part of troubleshooting a trim stop issue on your boat.

Listen for the solenoid/start relay

If you're trying to fix a trim stop on a boat, one of the first things you should do is check whether the problem lies with the electric tilt/trim motor or the hydraulic pump assembly. If you try to raise or lower the engine and nothing happens, you should first check that the battery is charged and that the battery switch is in the "on" position.

The next step is to listen for the solenoid/start relay while operating the control (tilt) switch up or down. If you don't hear anything, the problem is likely to be with the tilt switch, solenoid, or the wires or connections between the two.

The solenoid is an electromagnetic component in the circuit that controls the flow of electricity to the tilt/trim motor. When you press the tilt switch, power is sent to the solenoid, which then activates the tilt/trim motor to raise or lower the engine. However, if the solenoid is faulty or there is a problem with the wiring, the tilt/trim motor may not receive the power it needs to function.

If you don't hear anything when operating the control switch, the issue could be with the tilt switch itself. The tilt switch is the operator-controlled component that sends power to the solenoid when it is activated. If the tilt switch is not working properly, it will not send power to the solenoid, and the tilt/trim motor will not operate.

In addition to the solenoid and tilt switch, the problem could also lie with the wiring or connections between these two components. Over time, wires can become corroded, broken, or disconnected, preventing power from reaching the solenoid and ultimately the tilt/trim motor.

To summarise, if you're trying to fix a trim stop on a boat and you don't hear the solenoid/start relay when operating the control switch, the issue is likely with one of the following:

• The tilt switch
• The solenoid
• The wires or connections between the tilt switch and the solenoid

Test the motor

To test the motor, the first step is to remove the power to it by disconnecting the blue and green wires. Remove the quick-disconnect plug between the motor and solenoid, or detach the two wires where they connect to the solenoid or relay. Once this is done, use a jumper wire to apply 12 volts DC directly to the appropriate wire. If the engine is in the down position, energize the blue wire to raise it. If the engine is in the raised position, connect the jumper to the green wire to lower it.

If the motor fails to operate with power applied directly to the blue or green wire, the issue lies with the motor itself. If the motor operates, then the problem is a lack of power to the motor, which could be caused by a faulty solenoid or relay, bad connections, etc. Failed solenoids, relays, and corrosion at connections, relay sockets, and quick-disconnect plugs are some of the most common problems associated with tilt and trim system failure.

If the tilt and trim motor works fine, but the engine won't raise or lower, slips down when in the raised position, or won't stay trimmed, the problem is likely with the hydraulic pump or valve body assembly. Check the hydraulic fluid reservoir level. If the level is adequate, the problem is most likely with the hydraulic pump. A low fluid level indicates a possible leak at the seals, as does visual fluid around the piston assembly. Repairs typically involve removing and rebuilding the pump or replacing it at a qualified repair facility.

Hydraulic fluid doesn't evaporate, so a low fluid level indicates a leak in the system hoses, fittings, or seals. Check the reservoir for the presence of water, which can also cause issues, even if the system appears to operate normally. A common place for leaks to occur is the tilt and trim ram seals. Seals can fail for several reasons, from dry rot due to age and UV damage, to corrosion or pitting of the rams, which can damage the seals during operation. UV-damaged seals can be replaced, but if the rams are pitted, the only way to fix the problem is to replace both the seals and the rams.

Check the hydraulic fluid reservoir level

To check the hydraulic fluid reservoir level, you must first locate the reservoir. The trim-and-tilt system is electrohydraulic and the reservoir is cylindrical, located between the uprights of the engine mounting bracket. Due to its position at the waterline, the boat should be on land and tilted to a bow-down angle to level the reservoir.

Once the boat is in position, follow these steps:

• Tilt up the outboard and engage the support bracket. This is crucial for safety, as an engine falling on you or your hands can be catastrophic.
• Remove the screw from the top of the hydraulic reservoir.
• Fill the reservoir to just overflowing. Wipe away any excess fluid.
• Tilt the engine up and down to bleed air out of the system.
• Top up the fluid again if necessary.
• Repeat steps 4 and 5 as needed until the reservoir is full.
• Reinstall the screw.

If the tilt system is not working, there may be a hydraulic release screw on the side of the engine bracket, at the height of the hydraulic reservoir. Loosen this screw and try to lift the engine by the gear case. If it won't lift, loosen the screw further and try again.

Topping off the fluid is often a temporary solution. Even if there is no evident leak, there may be a small leak, and you may need to take your engine to a professional to fix it.

Check for leaks

If your tilt and trim unit fails to operate, the first step is to determine whether the problem lies with the electric tilt/trim motor or the hydraulic pump assembly.

If the tilt and trim motor works fine but the engine won't raise or lower, slips down when in the raised position, or won't stay trimmed, the problem is likely with the hydraulic pump or valve body assembly. Check the hydraulic fluid reservoir level. If the level is adequate, the problem is most likely with the hydraulic pump. A low fluid level indicates a possible leak at the seals, as does visual fluid around the piston assembly.

Hydraulic fluid doesn't evaporate, so a low fluid level indicates a leak in the system hoses, fittings, or seals. Check the reservoir for the presence of water, which can also cause issues, even if the system appears to operate normally.

A common place for leaks to occur is the tilt and trim ram seals. Seals can fail for several reasons, from dry rot (due to age and UV damage) to corrosion or pitting of the rams, which can then damage the seals during operation. UV-damaged seals can be replaced, but if the rams are pitted, the only way to fix the problem is to replace both the seals and the rams.

If the hydraulic fluid level is good, the problem is likely with the hydraulic pump. At this point, repairs typically involve removal and replacement or possibly rebuilding by a qualified repair facility.

Frequently asked questions