chas650r
Well-known member
408.......... I went through a similar issue w/ my new to me 2520 xld single f300 w/ seastar steering. my boat was a pristine fresh water only boat that was 300 hrs old when I bought it . I have had a lot of boats and this one tracked the worst of any i have had . every thing looked leak free and the fluid was very clean so I assumed the system needed to be bled. i also had a dead band at center on the helm. I spent wayyy to many hours chasing the issues I thought I had . I have been a auto mechanic by trade so a hydraulic system like this is simple and easy for me to comprehend. first I called seastar to make sure I understood the system, and did get some good info from them but no real eye openers. next per seastar, i emptied the system of all the perfect looking fluid , refilled w/ ATF as a recommended solvent and cycled / bled many times over 4-5 days to clean anything that might be in the system. then using over a gallon of aircraft fluid , flushed and refilled the system . I made a helm filler so I could have a foot of head pressure w/ an open reservoir above for filling and bleeding. very long story short, although the helm was very smooth and quite after all of this the dead band remained.
So it was time to investigate further. the helm itself simplified is a pump and a shuttle valve that directs fluid one way through the 2 hoses. the shuttle valve must see reverse pressure from the wheel being turned the opposite way before it moves (shuttles) and redirects fluid the other way. this valve movement is what you feel and hear just as you change wheel direction if the system is working correctly. there is a given amount of wheel movement that must take place before the shuttle moves and seals before fluid moves . this valve must not stick at all for the system to work at best, hence the reason for the atf flush.
so after all of the above my system was still marginal imo. with no load on the motor on the trailer on in the water at low speed the dead band is there but minimal. the entire system is very smooth , i have even disconnected the ram and checked the motor steer shaft ect , ect. when on the plane at speed the boat wanders more than i am used to and takes more wheel movement to correct than seems normal.
so after another call to seastar and relating all of the above to them they did admit to a given deadband as normal. it makes sense when you understand the function of the shuttle valve in the helm pump. the kicker in my case is that to keep steering effort reasonable on a manual hydraulic system w/ a motor of my size you must have many turns lock to lock at the helm ( close to 5 if i remember correct ). the lower geared the steering is the bigger the deadband ( slop) at the helm. so if I had say 2 turns lock to lock the deadband would just about disappear but would require power steering to move the wheel. this is why a i/o w/ power steering is so nice and precise. In a manual system like mine the helm to cylinder fluid displacement is a compromise.
So again after the 3rd call to seastar and to a aftermarket helm pump rebuilder I have concluded that what i have works correctly just not ideally.
The best diagnostic tool I got out of seastar is the shove test. it tells all and tests many things in simple test. at rest , you go to the back of the motor and just try to turn it against the ram and note the movement you can get at the ram to cylinder, up to 3/8" or so is considered by seastar to be normal. when the system is correct this is a combo of hose pressure flex and what is required to lock the shuttle in one direction or the other. I was initially shocked at the movement in mine and thought it was air but now understand why it moves and why the boat wanders. hose pressure flex can be a real problem w/ longer hoses and is why seastar offers big bucks low flex hose options. when you do this test if thing are free to move as they should you can hear shuttle valve move at the helm. any more than 3/8to 1/2" ram movement indicates 1 or more problems from air to leaks to bad valving, seals ect.
I still dont like mine and would sure like it better , but it my specific system i feel i might be beating a dead horse.
hope this helps. comments any one?
So it was time to investigate further. the helm itself simplified is a pump and a shuttle valve that directs fluid one way through the 2 hoses. the shuttle valve must see reverse pressure from the wheel being turned the opposite way before it moves (shuttles) and redirects fluid the other way. this valve movement is what you feel and hear just as you change wheel direction if the system is working correctly. there is a given amount of wheel movement that must take place before the shuttle moves and seals before fluid moves . this valve must not stick at all for the system to work at best, hence the reason for the atf flush.
so after all of the above my system was still marginal imo. with no load on the motor on the trailer on in the water at low speed the dead band is there but minimal. the entire system is very smooth , i have even disconnected the ram and checked the motor steer shaft ect , ect. when on the plane at speed the boat wanders more than i am used to and takes more wheel movement to correct than seems normal.
so after another call to seastar and relating all of the above to them they did admit to a given deadband as normal. it makes sense when you understand the function of the shuttle valve in the helm pump. the kicker in my case is that to keep steering effort reasonable on a manual hydraulic system w/ a motor of my size you must have many turns lock to lock at the helm ( close to 5 if i remember correct ). the lower geared the steering is the bigger the deadband ( slop) at the helm. so if I had say 2 turns lock to lock the deadband would just about disappear but would require power steering to move the wheel. this is why a i/o w/ power steering is so nice and precise. In a manual system like mine the helm to cylinder fluid displacement is a compromise.
So again after the 3rd call to seastar and to a aftermarket helm pump rebuilder I have concluded that what i have works correctly just not ideally.
The best diagnostic tool I got out of seastar is the shove test. it tells all and tests many things in simple test. at rest , you go to the back of the motor and just try to turn it against the ram and note the movement you can get at the ram to cylinder, up to 3/8" or so is considered by seastar to be normal. when the system is correct this is a combo of hose pressure flex and what is required to lock the shuttle in one direction or the other. I was initially shocked at the movement in mine and thought it was air but now understand why it moves and why the boat wanders. hose pressure flex can be a real problem w/ longer hoses and is why seastar offers big bucks low flex hose options. when you do this test if thing are free to move as they should you can hear shuttle valve move at the helm. any more than 3/8to 1/2" ram movement indicates 1 or more problems from air to leaks to bad valving, seals ect.
I still dont like mine and would sure like it better , but it my specific system i feel i might be beating a dead horse.
hope this helps. comments any one?