Hydraulic tilt/trim bleeding

[JMcIvor]

Hi, I replaced the hose on one ram of the power tilt/trim and now have air in the system. Anyone know how to bleed the hydraulics on the power tilt/trim of a 50hp Blueband Mercury?

 

[ThumbPkr]

Re: Hydraulic tilt/trim bleeding

The Merc manuals explain how to bleed it but I think if you cycle it through a few times it should bleed itself.I have worked around hydraulics all my life and seldom have any bleeding issues.It is common around heavy equipment to blow hoses from time to time and once repaired you refill the reservoir and go back to work.The manuals tell how to do it for a reason I am sure so others may have a better answer for you.
I installed the Mercury power trim on my boat last summer and it works great and I didn't bleed anything.The parts came from several sources and the reservoir was empty.Ron G

 

[erie_guy]

Re: Hydraulic tilt/trim bleeding

JM,
ThumbPkr is correct, just top off the reservoir with hydraulic fluid and cycle the engine up and down a few times - the air will come right out via the air vent on the reservoir. Just make sure the level in the reservoir is close to full when you start as you don't want to be pumping additional air into the hoses and cylinders. I am not sure what type of fluid your engine needs, but it is probably written on the side of the reservoir. Both ATF and motor oil have been used in the Mercs.

Happy Holidays,
erie_guy

 

[Chris1956]

Re: Hydraulic tilt/trim bleeding

JM, Some Merc PTT units (from the 70s and early 80s) can require bleeding. Also, refill with the same type of fluid as you have in it now. Clear red is likely ATF, so use some Dextron ATF to refill. Clear brown is likely 5W-30 motor oil. Use the same to top off.

If it were me, I would loosen the new hydraulic hose where it attaches to the trim cylinder and run the pump to bleed most of the air out of the line. Your cylinder may have a bleed screw (stainless slotted screw) next to where the hose bolts (up circuit) on or on top of the trim cylinder (down circuit). Each may be loosened and the pump run in the correct direction to bleed the cylinder.

 

[Laddies]

Re: Hydraulic tilt/trim bleeding

Here's a diagram of the cyls with the bleed screws labeled

 

[merc850]

Re: Hydraulic tilt/trim bleeding

There must be a good reason they put this in the manual.