Motor is triming it self while getting on plain??

Question I noticed my main motor was trimming itself down when it was on plain. Anyone have any possible answers. Thanks in advance!

Is the motor slowly falling down when you’re on plane? If so you likely have a leak in your trim cylinder.

Seals going bad in the T&T cylinders. Had the same problem with a merc 115. Mechanic said he can either go in and tear it apart, fixing the problem spots or put a new unit on. He said it could be up to 20 hours in labor to tear it all down and fix the seals and whatever else is warn out then replace it all and re-mount it, check to see if it is working and go at it again if not. 20 hours at $50 an hr shop charge = $1000. Then he said he can replace the whole thing with a brand new unit and it would be $975 with labor. I opted for a new unit.

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Is the motor slowly falling down when you’re on plane? If so you likely have a leak in your trim cylinder.

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X2.

yes like others said!!! you could fix it yourself!! go to dealer tell them the problem.. order seals and O rings for cylender.. 2 hours and 20 bucks it will work like new!!!

Yes, its only happended twice and has been used in between those 2 incidences without any issues. Could that possibly be a result of needing more fluid? Or is it only going to get worse with use. Going to be using the boat all next week on vaca.

if it has fluid to lift it to begin with and then gos down it is leaking somewhere! probably an oring that is going bad!

lift motor all the way up.. lock into position.. disconnect cylinder from motor! take large pipe wrench and unscrew end of hydro cylinder. the end and shaft will pull out.. replace rubber and plastic O rings with new reassemble and your done!! its that easy to fix!! hydro cylinders are about the easiest thing to repair.. !!! just takes a few larger tools and some grunting to get them apart! dont forget to refill.. push shaft all the way down and fill cylender from end before screwing top on then top off threw fill hole!

The other thing it could be is the relay going bad. Our Merc started trimming up on its own. That about got us run over at the start of a tournament before we figured it out. There is one relay to trim up and another to trim down. What we did was swap the two to verify and then it trimmed down on its own. It is probably the seals in your case but just something else to check.

The relays should be checked, sometimes they do stick causing the same situation you have. Remember there are two stages to your pump a tilt and a trim stage. The tilting stage will allow the motor to come down if under power until it hits the trim stage. The trim stage should not allow the motor to drop under power. Just want to make sure you understand this part.