I have an aftermarket Imco external hydraulic twin outdrive steering system. I developed a leak in a stainless braided hose, two of them showed split at the swedge of the four. This was after the steering system had been bled after some rusty fittings were replaced elswhere. Does the system require a specific amount of air in order for the drive rams not to overcompress the system? Should the volume relate to the amount of oil displaced by the outdrive rams going up?

As far as I know, no air is the correct amount. A hydraulic system works because the fluid is incompressible and moves the mechanical parts. Air bubbles cause slop in the system because they can be compressed allowing the drive to move when it shouldn't. After you've bled the system as best you can, the remaining small amount of air will bleed itself out of the system through the reservoir under normal driving conditions. Once you've bled the system, you shouldn't be able to move the drive more than about an 1/8" left or right. After a day on the water, you won't be able to move it at all by hand.

If your hose split, it was either old, or it was not rated for high enough pressure.

power steering reservoir should be half full.

yikes you would think the hoses would last more than a few years its all set thanks

You don't need to bleed the system. Hydraulic steering systems have a pressure & return side & bleed themselves.

I can feel my system "break loose" so to speak after it sits for the winter, I think it is bleeding itself??

Yup.

I always disconnect the rams to the drives to let them fully retrack and extend when I bleed them.Machine Marine recommends bleeding it.The rams will not self bleed.
http://www.offshoreonly.com/forums/s...power+sterring


http://www.everettperformance.com/im...G%20SYSTEM.doc


Member Falcon is very knowledgeable on this ,try to pm him.

Hope this helps
Rob

Why will they not self bleed? If you turn the wheel/valve on any hydraulic system it will allow you to bleed out the air by going into a "bypass" of sorts while the system is online.
I feel like I know enough about hydraulics to be talking about this. But my knowledge is on machine hydraulics so there may be some differences.

The pressure/tank hydraulic circuit will bleed itself because it is a circulating circuit. The hoses that run to the rams deadend in the rams, the fluid doesn't run through them and back to the helm.