By Bobby Lane
Yamaha Pro Staff
It’s easy to overlook the importance of the tilt and trim unit on your Yamaha outboard motor, but it’s one of the most essential components for getting the best performance out of your boat and motor. Tilt and trim adjust the angle of the motor and thus the running surface of the boat, so they determine the smoothness of the ride, the grip on the water, the ability to jump on plane and many other operations that you often don’t even think about.
For instance, when running across a lake where you have to run through a lot of thick grass, the ability to trim your engine level (about halfway up) allows you to avoid pulling weeds into your water intake and overheating the engine. The same goes for running in rough seas where the ability to trim the engine all the way down allows you to keep the bow close to the water so you end up with a smoother ride and don’t pound into the waves.
When your tilt and trim doesn’t work, you know it right away. It’s then that you begin to realize how much you depend on your tilt and trim on a daily basis for normal boat operation.
The Yamaha Owner’s Manual suggests you perform standard maintenance on your power tilt and trim after the first 20 hours, then every 100 hours or annually for the life of the motor. It’s easy to do, and most times just involves a good visual and a fluid level inspection. That said, there are parts of the system that I still attend to on a monthly basis.
Because I’m running around the country fishing tournaments and towing my boat over dirt, sand, and dust on a regular basis, I try to grease the top of the rams on the tilt unit on a regular basis. In the rear battery hatch of my boat, I have a little storage compartment where I always keep a tube of Yamalube Marine Grease handy, and every time I open that compartment it reminds me to check my trim unit.
I use Yamalube Marine Grease because it’s made to withstand the saltwater environment, which I consider the toughest place for anything made of metal. I’ll just squeeze a little bit of grease on my fingers and rub it on the tops of the trim rams and their contact points on the bracket pads. You should do this on a regular basis.
Grease gets wiped or rubbed off and washed down all the time, and you’ll know when the rams are dry because they tend to rub or create friction when raising and lowering the motor. You’ll know, too, when you hear a kind of a screeching sound, which is the metal of the rams rubbing against the base. The second you put a little grease on them, the sound goes away.
As long as you’re applying grease to the trim rams, you might as well inspect them for leaks, which is a common issue with power tilt and trim systems. Hydraulic fluid can be a burgundy or clear color and has an extremely low viscosity, so if there’s any way for it to leak out of the system, it will. Sometimes the actuator ram seals will leak and the fluid will be around the base of the ram, or drip down around the power tilt and trim motor.
An electric pump runs the hydraulic fluid in the power tilt and trim system, and if you get a leak, the hydraulic fluid will ooze out and allow air to replace it in the system. When that happens, the motor will usually tilt all the way down and will not go up or will stick.
Hydraulic fluid doesn’t evaporate, so if you can hear the trim motor running but your outboard won’t tilt up, you likely have a leak. You can replace the fluid as a short-term fix, but you’ll likely have to get the leak fixed by a Yamaha Certified Mechanic, although sometimes the leak is so tiny that it takes several months for enough fluid to leak out of the system to impact the power tilt and trim hydraulics.
If you see any fluid on the rams or the motor is stuck in the down position, you can easily add hydraulic fluid to the system. I use Yamalube Performance Power Tilt and Trim Fluid because it’s non-foaming so you don’t get any air trapped in it, and it’s made to resist the extreme heat and high pressures that take place inside the hydraulic system.
When I change the power tilt and trim fluid or add fluid, I’ll trim the motor all the way up and then put down the motor safety clip, so when I open the system the motor can’t accidentally fall down. If the motor won’t trim up, you can release the trim lock by turning the manual trim release screw on the port side of the engine mount, and then lift the motor by hand and use the motor safety clip to lock it up. Then I’ll lower the tongue of the trailer so the transom of the boat is level. That will ensure the fluid will be at an even level when you add fluid to the system.
Then you just remove the hydraulic fluid fill screw near the top of the trim reservoir and add fluid until it starts to overflow. Then trim the motor up and down, try to add a little more fluid and trim it up and down again. Do this several times to bleed all the air out of the system, and then put the hydraulic fluid fill screw back in, wipe off the excess fluid and your power tilt and trim should work. After you refill the system, if the ram works but won’t hold the motor up, you likely have a major leak or a bad check valve and need to get your motor to a Yamaha Certified Mechanic immediately.
Over time, the power tilt and trim motors can experience corrosion, especially if you run your boat in saltwater. One way to prevent this is to keep the trim rams fully retracted when not in use.
If you get to the ramp and the motor is halfway up, but won’t go either way when you press the trim switch, you might have a corrosion build-up issue. Sometimes you can bang on the power tilt and trim motor with the head of a screwdriver or wrench and it’ll knock some of the corrosion off the brushes and the engine will then go up and down. This is only a very temporary fix, so if this happens, you need to head for your local Yamaha Certified Mechanic, so that you don’t get stuck out on the water later.
The last thing I do as standard maintenance on my power tilt and trim unit is inspect the rams for corrosion, which can cause friction and excessive wear. If you trim the motor up for a prolonged period or store it, the corrosion can adhere to the ram tubes and the motor can lock tight, but that’s pretty rare. It can also cut the seals on the trim cylinders when they retract. Most of the time, however, the corrosion is minimal and can be wiped or brushed off and then greased to prevent further issues.
As long as you’re there, you might as well check the zinc anode to see if it needs to be replaced or has come loose and needs to be tightened. If the zinc anode shows signs of wear, you should replace it immediately. If there are any bonding straps in the area, check them, too.
Do these little maintenance operations and you’ll avoid more profound power tilt and trim issues down the road. If an ounce of prevention is worth a pound of cure, a half hour of maintenance is easily worth an afternoon or more at the boat mechanic. That’s time you could be out fishing!