Rebuilt the trim pistons on my 1998 BF90. Top seals were leaking. Bled it, all good. Then, saw the Tilt actuator was doing the same. Rebuilt the piston and actuator. New seals all around. Bled it numerous times, with all air seemingly out, but while it would tilt down to the trim rods, where the rest of the way down was supposed to be done by the trim rods, they wouldn't lower down. I could manually lower the unit with the release valve, and they would trim up normally, they wouldn't lower. I suspect a plugged channel in the housing. When I got tired of bleeding the system, I reopened up all three of the cylinders, removed the trim cylinders, and ran a small wire up the ports at top of the cylinders, two on each side. One was an equalizer port, which ran to the other side. The other went up somewhere, and when I poked into the right port, it gushed out fluid and air. Possibly a blocked line in the casting of the unit.
Has anyone else experienced this problem? After reassembly, same thing happened all over. Noticed that I couldn't get rid of the "Burble".or gurgling sound, very slight, right as the trim bottomed out when the lowering was done with the manual relief valve.