It seems so backwards that it wont go down. Not going up I understand, its gravity and outdrives are heavy. The damn thing should fall down when I hit the switch. i was shocked that it didn't fall when i unhooked the pump.

Mercury clearly states in the TRS Service Manual #5 to use 10w30 or 10w40 MOTOR OIL in all their trim pumps Prestolite and Oildyne


Now I do know someone that uses ATF oil in trim pumps!!!

If it don't fall with the lines disconnected there is something wrong in one or more of your cyls.I've seen a piston come apart before in a TRS trim cylinder and locked it all up.

My drives on my Formula 302 say ATF on them. The 311 says ATF on the tabs but 10-30 on the drives.

The pump puts out more preasure in the upwards direction. Less on the way down. My guess is that your scraper ring went bad and then the next piece in ussually freezes up (second picture down on this link http://www.ebasicpower.com/c/MER3E/ )

I put a remote button on mine so I could lower mine by myself

I only have trouble with one of my drives. When I am underway I Kick up the RPM's alittle and then hit the switch and it goes right down.

You guys have been a big help, thank you. I'll let you know in the morning what it was.

Bad trim cylinders. Those suckers are STUCK. It took a breaker bar to even spin them. Whats crazy is they look better than most externally. Rebuildable?? Replace?? I need four of them.

U can rebuilt them easy and not allot of of $$$ needed.

You say they are the external line design?They have one of the lines running up the side of the cylinder on the outside?Overhaul kits for those are $120 each.Then if you have any 'hard parts' damaged inside (which is very possible)you will be most likely out of luck.It is almost impossible to find parts for those.That was a junk design.You would be better to switch to the internal line design.Just my opinion.There is a nice pair on ebay with the lines and connector block for $400 or make offer.The guy lives in Irvine.You can contact him and he may have more than 1 set.I know at one time he had 2 complete drive setups he was parting out.You see them pretty often on ebay and Offshore Only classifieds.I bought a nice pair off ebay for $200 that I am keeping for spares.