Trim Letting Down Over Two Days

[Tantalus]

Possibly been answered several times already but can’t find. All of a sudden engine is slowly going down from the full trim up position (Trailer position) over the period of a couple of days to being completely down. It’s a 1999 70hp. Does it simply require hydraulic fluid top up or is it a sign of leaking seals?

[fairdeal]

Does it simply require hydraulic fluid top up or is it a sign of leaking seals?

It doesn't require any more fluid to 'stay up' than it does to get there.
Something is leaking internally: either the piston seal, or a valve.

[robert graham]

My 1999 Yamaha C90 has always leaked down very slowly....The tilt lock lever will hold it up fine.....I use a transom saver for trailering. ...As Fairdeal said, we've got some kind of slow internal leak, but I don't consider this a problem...for me, anyway.