Mercury trim sender

[Jerry]

Hi,

I was trying to check why (on Merc 90, 4-stroke, 2005) the trim gauge is almost always showing UP, regardless of the engine position. Removed the trim sender, when rotated manually the gauge is showing both DOWN and UP - so electrically everything seems to be working correctly.

When I looked closely at the "screwdriver slot" of the pin into which the sender slots in, it seemed that the slot in the pin is rotated 90 degrees CCW compared to the position required for it to be in to show correct trim readings. When I've tried to gently rotate that pin with a screwdriver I was surprised that it did rotate - I thought that the pin should be fixed?

Is this behaviour correct? Should I just rotate the pin to suit the sender's position to send correct trim signal, or should I start getting worried?

[Davie]

The pin should not rotate, it's locked in position by a nail with a serrated shoulder. This has fallen out.

[Jerry]

Thanks for diagnosis, that's exactly what's happened.
I've ordered a new pin and was a bit surprised that it wasn't a serrated nail, but an interference fit triangular one. For me it doesn't look like the best solution, interference fit in a high vibration setup won't last long (as proven!), so I've added some Loctite 271 to keep it in place. It's taken a fair amount of hammering to put it fully in - I hope I'll never have to take it out!

What's the acceptable amount of "trim leakage"? I think the engine has dropped about 1cm over 3 days. I'm keeping it almost vertical so it doesn't trap any condensation water which could freeze.

[Jeff]

Just be careful when you knock the pin back in place not to miss and hit the tilt ram ,,, and subsequently get a weeping ram ! Guess how I know 😱

[Pikey Dave]

Originally Posted by Jerry

Thanks for diagnosis, that's exactly what's happened.
I've ordered a new pin and was a bit surprised that it wasn't a serrated nail, but an interference fit triangular one. For me it doesn't look like the best solution, interference fit in a high vibration setup won't last long (as proven!), so I've added some Loctite 271 to keep it in place. It's taken a fair amount of hammering to put it fully in - I hope I'll never have to take it out!

What's the acceptable amount of "trim leakage"? I think the engine has dropped about 1cm over 3 days. I'm keeping it almost vertical so it doesn't trap any condensation water which could freeze.

10mm over 3 days is bugger all. ALTHOUGH it might get worse under power when the engine is pushing. Try undoing & retightening the manual release valve a few times, it might be that that's not seating properly.

[Jerry]

Originally Posted by Pikey Dave

10mm over 3 days is bugger all. ALTHOUGH it might get worse under power when the engine is pushing. Try undoing & retightening the manual release valve a few times, it might be that that's not seating properly.

I'm going to wait until temperatures get back to normal before redoing the manual release valve. I wonder if that's related with cold temperatures in any way? I don't recall that problem in November (but then I didn't bother with keeping the engine vertical - no risk of trapped water freezing).
I'm assuming that my gentle tapping with a small hammer didn't do any damage - if it did, whatever gave way wasn't any good.