Mercruiser trim problem

[jdunsworth]

I have a 1976 Tri-Sonic with a 302 Mercruiser. Just got this boat about 2 weeks ago and its a little rough but runs smoother then my truck with a fuel injected 302. <br /><br />I am having a problem with the tilt/trim system. When driving the boat the out drive will slowly trim up. Doesn't matter if i am at an idle or at full throttle. It doesn't do it fast but after 10 minutes or so i have to trim it back down a little. <br /><br />Has anyone seen this before or have any ideas on what i need to check. Thanks.

 

[Reel Poor]

Re: Mercruiser trim problem

Thats a new one on me. The only way I can possibly imagine the system would trim UP by its self is if someway you are inadvertly hitting the trim switch, or there is a wire shorting to power. For the system to power the drive UP the trim motor has to run.<br />

 

[jdunsworth]

Re: Mercruiser trim problem

The trim motor is not running it up. Its like the cylinder is bleeding out but it goes up instead of down.

 

[vipzach]

Re: Mercruiser trim problem

Welcome to iboats!<br />Does this problem happen while you are driving only, or does it happen when you are just sitting?

 

[jdunsworth]

Re: Mercruiser trim problem

seems to be when it is in gear.

 

[qaztwo]

Re: Mercruiser trim problem

I had same problem on my 72 tri hull. Ended up being the trail-out valve in the valve assembly on trim pump. Ended up removing the hex screw on the return side of the pump and cleaning the check ball and passage. Good luck.