Merc outboard trim/tilt

[Bertramp]

The outboard engine on my 21 Whaler is slowly but surely lowering itself from the full up tilt position. It is a 2006, 225 Optimax. Is this probably O rings in the cylinder ? How tough to fix ?
thanks

[IRGuy]

I used to have the same problem with one of my twin Yamahas. Have you checked the level of the hydraulic fluid in the tilt/trim reservoir? When mine was slow to respond or did not stay up constantly that was the problem. If your shaft seals are leaking you should see external signs of a leak running down the side of the cylinder. Mine leaked at the shaft seal, but it was not so bad that I ever took the time to fix it. It was easier to add some oil 2 or 3 times a season.

I am not really very familiar with Mercs, but don't you have a lock to keep the engine in the up position when you are not using it? Using it would take the pressure off the system if the piston seals were bypassing. As I recall the Yamaha Owner's Manual recommended to use the lock when the engine was not being used. I used it for several years until it froze in place.

[Bertramp]

boat is stored in the water, so the storage locks are tough to use. I will check the reservoir though, good call. thanks

[IRGuy]

By storage lock, I mean a small lever located under the engine cowl behind the "hinge" shaft the engine tilts on... when the engine is tilted up a small arm can be manually rotated forward so it moves under the engine to prevent any downward movement. If the engines are up now and you can get under the boat cover you should see it. If you have an engine manual it should be mentioned there as well.

Good luck!

[Bertramp]

I know whatcha mean, it's just tough to get to with the boat in the water.

[Rawleigh]

Also check that the manual bypass valve to let the motor down is tight. I think it is a screw that you access through a hole in the side of the mounting bracket.

[IRGuy]

Good point Rawleigh.. I forgot about that!

[Pete Fallon]

Bertramp,
Merc/Mariner have had this problem since the late 1980's, Don't hold me to it but I remember either a service bulliten or a recall concerning the trim motor seals. It's not a real hard repair, however if there is any corrosion on the top of the barrels it turns ugly very quick. You might end up replacing the entire trim system, just to save time and scun knuckles. When I was selling engines back in the late 80's we always told the customer to use the trailer relief lever, when storing or trailering for a long distance. I always put a 2x4 block under that area when towing to 26 SKA tournments every year for 3 years , never had one fail. Again check the seals, tighten the manual by-pass screw and keep full of fluid. You might need the hot wrench to remove the barrel tops if there is any corrosion. Good luck.