Scenario: '94 nitro that has always run great. Recently I noticed that the trim hasn't been working as well, and it's progressively getting worse. There still seems to be plenty of power left in the trim/tilt motor, but when I start to raise the engine it will not go all the way up on it's own. At random points it was almost stall out as it's going up. If I want to raise the engine all the way to the top I have to manually hold the "up" button on he side of the engine and pull the skeg up in order to get the engine to rise all the way up. I have admittedly never done anything to service hydraulic system for my trim/tilt function. I don't believe that there are any leaks or cracks in the lines. I've been reading around on the internet, and I'm thinking that it may help to bleed the hydraulic lines. I don't even know if my boat is worth the money of replacing the etire trim/tilt system, And i've been told just replacing the trim motor is like $300. Any suggestions and advice would be much appreciated.

Trim the motor up all the way, remove your resivor cap and add some trim fluid untill it runs back out the cap hole. reinstall cap and try triming all the way down and back up, did that help or fix problem? if not, probibly time for some part on the unit. I have complete trim units for 400.00 to 600.00 depending on two wire or three wire units. Thats is the hole trim system, not just the motor, and that is exchange for your old one. I rebuild them. coms with warr. Thanks Cary

What hydraulic fluid do you recommend?

ATF or power steering fluid. Cary

WHen it "stalls" is the trim pump still making noise like it's attempting to lift? Or cutting out?
I only ask, because I had this happen to my Evinrude, sometimes it would actually stop moving in certain positions (and got worse recently)... last time it happened I had to idle back about 4 miles to the ramp because it was stuck "trimmed up" and I couldn't get on plane.
Possible culprits: Trim motor (first thought), bad wiring (2nd thought) bad connections (3rd thought)....
Tested trim motor directly to battery (bypassing all controls)... worked every time...would not work reliably or at all when reconnected.
Tried bypassing circuits with bypass wires from power distribution panel (clipped on leads) to motor... worked most of the time.
A-HA! (I thought)... bad wiring or connector in the cross connect cabling... built new cabling, rebuilt the connectors, reconnected everything, and just knew it was good... hit the switch... nothing.
Then I found the problem, it was the actual distribution panel circuit board... when I moved the male connectors (pair) from the panel... one of them noticeably wiggled (also was blackened some)...
Reason it worked when I bypassed... the weight of the clipped-on lead was pulling the contact downwards, making contact across the broken solder joint.
This is also why it was intermittent, just wave action/bouncing for awhile was good enough to sometimes make, sometimes break the connection.
Cracked open the power distribution housing (literally, it was ultrasonically or otherwise adhesive glued over the PCB)... found the totally busted solder joint, cleaned, resoldered, and glued back together the housing, reinstalled everything and perfection.
So, anyhow, just something to think about, a seemingly obvious diagnosis (trim motor failing, it's old and looks like it could fail any day), can be totally wrong even though it seems to make sense.
Oh, a replacement power distribution module (the main power module for this boat, all engine relays, etc go through it)... was something like $360 used. Cost me some solder, gorilla glue, and a few hours of careful work to disassemble and crack the case without breaking it (succeeded on the division line). Was worth the attempt, and glad I did, as we didn't have the money to replace it anytime soon if I failed, and nothing to lose if I didn't succeed.

Thanks guys! I really appreciate the detailed advice Chris! I took off work an hour early yesterday to go home and tinker with it. I bled the air out of the fluid reservior, and it seems to have fixed everything. It probably took me a total of 5 minutes and I even had enough time to catch the last couple hours of daylight on the water. Slammed the whites and hybrids too! Thanks again, and tight lines!