First time taking my 26’ Firehawk cat out today. It has dual IMCO hydraulic steering and no reservoir tank.
Very hard to steer when idling. Then later I could tell it had air in the system.
I’m guessing it should have a reservoir tank or is it possible for it to work correctly without one?
I’m familiar with my previous Fountains Latham steering. They had tanks and were self bleeding.

When I got home i tried turning the wheel one way and it pushed air/fluid out the pump cap. Drive did not move.
Got out of the boat and moved the drive back and forth and I could feel air in the rams.

Just trying to figure out where to start. Should I crack a ram line and turn the wheel to one side? Can I get it to work without a reservoir?
I knew this boat needed work but things keep snowballing and the snowball is starting to get big lol.
Thanks for the help.

Is it full hydraulic or add on with still having a cable helm??

Full.

Sounds like you need the sealed cap with a reservoir tank

Yep.
The top of my PS pump has a welded on cap with a fitting that goes to my reservoir
Mine is like the pic in this ad OffshoreOnly Classifieds - Boat Classifieds - Boat Parts

I have run 2 full Imco systems without the tank and it will work fine, you just have to keep the reservoir filled as you bleed the system. Your system needs to be bled. There are multiple good threads on here on how to do it. It is a major PIA and a 2 person job. If it is an old system get a new filter. Post some pictures:

That’s good to hear. Answers my main question. I found it odd that it didn’t have one but also thought it had to work because it’s been like that. Not sure if the boat came with the hydraulic steering or was added on at some point. The boat sat 10 years with the drive up. Drive would not go down because air was in the rams. Guess the same thing happened to the steering rams.
Anyways, yesterday I got some air out by pushing the drive to each side and opening a line. Now it will steer without running.
I found bleeding instructions. I’ll get someone to help me with weekend. Thanks again. I’ll give an update next time I run it.

Keep working the trim up/down to get rid of the air. Same on the steering R/L and keep the reservoirs full. If it does not bleed the air out, need to find the issue. Internal seal, loose hose fittings, not cycled enough after it had been drained or flushed. It is tedious and you need a helper, but it should work. A side note is the pumps will make excessive noise when there is air in the system.

I talked to IMCO and the rep said the same thing, the system does not need an external tank. I did bleed it. Feels much better on the trailer. I was going to wait until I got it on the water to provide an update but that’s going to be a couple of weeks.

When I installed ext steering, I didn't want to run an eng to bleed the sys. My power steering pump has a 3/8" internal hex (think yours does too). I took a 3/8" allen wrench and cut off the short "L" part. Chucked it up in a 1/2" elec drill and was able to spin the pump. Gotta remove the belt, verify correct rotation and drill needs a trigger lock of some sort that keeps it powered when you let go.

You might need to rig up something to hold the drill. In my case, I was able to wedge the drill up against something (trim pump?) and I was able to use it hands free. I was able to bleed everything by myself without breathing any exhaust or getting wet.