Should I trim down while running?

[Shadow66]

Have a 2002 3.0L Mercruiser Alpha 1 Gen II Sterndrive. I was browsing through some past posts and saw that some say you should always keep your outdrive trimmed down when running the engine at all. Is this true? Some said it was not necessary and downplayed it.

I called a dealer yesterday and asked and he sounded vague but leaned toward doing it saying it was hard on the drive shaft in the up position but mostly spoke of the "noise." I asked if it was just when the engine was running or if were engaged in gear only...he said whenever it it running only the prop shaft is not turning and everything else is engaged.

I have run it up quite a few times when on the muffs and it seems fine but I do not want to damage anything or wear anything out.

I already have made up my mind to lower from here on when the engine is on at all (not just engaged), unless I hear some evidence otherwise.

So what's the skinny on this?

 

[gcboat]

Re: Should I trim down while running?

There is a 'tilt - trim' position on your lower unit. If you keep the unit within the 'trim' position you will be fine. Do not use it when you pass the trim parameters and go into the tilt position.
Just think of it going very slowly - trim position - . Faster - tilt, or trailer.
Remember that all of your shifting is done within the lower unit itself so the drive shaft is constantly in motion. Any undue strain will cause premature wear on the u-joint ( hence the noise the dealer was speaking of ).
If you're in any doubt just leave it down and your worries are gone.

 

[jam1ej20]

Re: Should I trim down while running?

Your dealer was right. Anytime the motor is running, the driveshaft is rotating. If the drive is up during this time, it puts considerable strain on the u-joints. Engaging forward or reverse is localized to the lower portion of the drive and the driveshaft is not affected by this. Keep your drive down when running the motor and your u-joints will thank you.

 

[flargin]

Re: Should I trim down while running?

I just completed adjusting my Bravo trim using the service manual. I have attached the page indicating the "Warning" which should be posted on the boat... i.e. the mercruiser recommendation.

The summary is your "trim" range (on my boat out to 21" extension) is where you can use full throttle range. Extended beyond that (to the "Trailer" range and they do not recommend operation above 1200 RPM.

This being said, I know I have heard the knocking of the U-joints, and it is not a great thing to do. I do extend into trailer to power up to my trailer, as to not take the blades off my prop.

And I would never run it at full "Trailer", that is a sharp angle for you to transfer the power....

 

[imoutnumbered]

Re: Should I trim down while running?

Under anything other than idle, I'm always in the trim range. Approaching the sand bar, I have to go into tilt/idle configuration!​

 

[Maclin]

Re: Should I trim down while running?

When you have to go into tilt/beaching range out on the water to get to shore try to time it where you can build up enough momentum to coast in then shut the engine off and then raise the drive. When leaving push off until the drive can be lowered enough to get out of tilt/beaching range before starting. That is easiest on the equipment.