How far should the drives trim up when underway? Mine will go up to 3 on the mechanical indicators and stop. Seems to me they should trim up a little more. Boat is an '88 Formula 357/TRS drives.
Thanks, BC

Should be able to trim them to the top of the guage and then a bunch more. Certainly past 3. Have you actually looked to make sure the drive is not lifting? It is posible that the cable is out of adjustment or stuck. When you trim all the way down does the indicator go to the bottom of the guage? Once you trim up if the drives stop then you may have your trailer position out of adjustment. That is on the (I think) left side of the drive. To test that hit the trailer button and see if the drives go up higher. I have disconnected that trailer BS on all my boats, it drives me nuts.

The guides on the sides of the drive should not go so high as to come out of the guides on the gimble ring while underway. If they aren't getting near this point then you can adjust the trim limit switch to let them go higher. Drive should only go past out of the guides with the trailering switch. Limit switch is on the port side of the gimble ring.

I checked the drives with the indicators and they do not move much, so I think the indicators are reading correct. As soon as they hit 3, the pumps shut off. The starboard side moves to about 3 1/2. Sounds like a limit problem to me too. I'm pretty sure the trailer switch doesn't work, I never use it or raise my drives to trailer because it sits high enough and trailer has a rear gate. I will check it out soon.
Thanks, BC

You need to adjust the trim limit switch

According to the Merc TRS manual the trim limit switch should be adjusted such that the trim cylinder should be 21-1/2" max bolt center to bolt center.

Thanks, I should try and find a manual and make it easy on myself.
Thanks for the info guys, BC