See if this helps for refilling your trim/tilt system. Pappy - If you had any corrections to this info ... I'd surely like to know it, thanks!
Filling OB Hydraulic Trim/Tilt Systems:
To properly check the fill, the trim/tilt rams must be extended. Raise OB all the way up. If you can't via the trim motor, then back off the manual release valve and with extra help, tilt/raise the OB all the way up and set it on its mooring/full raise lock, or some type of block (for safety) and then re-tighten the release valve.
Tilt reservoirs are easier and best filled IMHO when the boat is on a trailer, as you can lower the tongue all the way to the ground, as you want the tilt/trim reservoir as straight up & down as you can get it. This procedure is also best done IMHO with a helper to assist you, as they will keep their finger on the t/t UP button on the OB cowl, when needed.
Trim/tilt the OB all the way up and engage the full-up tilt support (or use a block ... as you do NOT want an OB to fall on any bodypart :shock: !). Slowly open the t/t reservoir cap (allowing air to escape) and insert the trim fluid tube/nozzle. I use a small long/slender nozzle on the end of the recommended trim fluid container to help keep it in there. Some people report using am empty and clean 'squeeze ketchup' bottle ... hey, whatever works!
Now this is where your assistant comes in. Have them press AND hold the t/t UP button as you put in ALL the fluid it will take. Keep pressing UP while the OB goes all the way up (off its supports), you will hear the t/t motor hit the bypass valve (the motor sound will change) and until the t/t reservoir won't take any more fluid and it starts to drip/gush out. Mind you, your helper's finger is still ON the UP button ... and while their finger is still pressing the UP button, quickly put the trim reservoir cap back on. All done! DO NOT let them them remove their finger from the UP button until the cap is completely on.
FYI: The concept behind "holding the UP button pressed while filling" allows the trim motor to suck in all of the fluid it can via the hydraulic system. Doing so in this manner, you should not have to top off the reservoir again, hopefully for a loooooong time.
Bleeding OB Trim/Tilt Systems:
OB tilt/trim units are "self-bleeding" and you should always perform these "purge cycles" to follow even if you don't need to add any more fluid. To purge/check, remove the tilt lock (if engaged) or block and cycle the OB down by "jogging" it down, in 2-3 seconds runs. Then rest the motor a few seconds (akin to NOT cranking on a starter motor continuously), then cycle it UP all the way in one long blast.
Rest/pause again ... 10 seconds or more ... then repeat that complete cycle a few more times to ensure that it has bled all the air out of the t/t system. When bled of all air, you won't hear bubbling or gurgling as the OB starts its up or down cycle ... you should just hear a smooth start of the rams in motion.
Yams especially - Make sure to keep the rollers lubed to eliminate those gawd-awful squeaks ... but lube contact points for all brand OBs