850 Merc hydraulics

[Chris1956]

Re: 850 Merc hydraulics

GA, I had a '76 Merc 1500 with factory PTT. The directions I quoted came from the Merc owners manual, and Merc Service manual. Maybe they changed it after 1978, when I purchased those manuals?

Now if you look at the location of the up bleed screws, you can see why they would want you to remove the cylinders and point the bleed screws up. If you don't do that an air bubble can remain in the PTT Cylinder, just above the hydraulic lines.

 

[GA_Boater]

Re: 850 Merc hydraulics

I believe you, Chris. It's just like brake bleeding, mushy if you don't get the air out. The procedure I have is like a Mercruiser, where you don't have bleed screws. Maybe a Merc I/O guy wrote the method I have. More than anything, it seems Merc put out conflicting info. I'm not sure of the date on the my TnT manual.

 

[Chris1956]

Re: 850 Merc hydraulics

GA, Mercuisers are bled exactly as you have quoted. The PTT pump is generally higher than the trim cylinders, and the trim cylinders are horizontal, with the hoses on top. Gravity will cause the air to travel to the PTT hoses and then back to the pump.

 

[850Merc]

Re: 850 Merc hydraulics

Thanks guys, I have been putting off this part for the meantime. I have been working on other parts of the inside of the boat, but I'll make sure to follow these instructions when the time comes. I was hoping to avoid removing the cylinders, but I want to make sure I do it right. I'll review the manual that GA sent me too.