Hydraulic Steering

[Javelin360]

My boat has hydraulic steering and was wondering what fluid you use to refill? Can I just poor the fluid in or is there a special method?

[orchard frank]

On the SeaStar hydraulic steering systems, there usually is a filler cap near the steering wheel. You can fill or add here, the manual gives you the proper levels. I would assume the info is on their website as well. However, if the level is too low, or if you have a leak, there is a bleeding procedure you must follow to purge any air out of the system. If it is leaking, that must be repaired, just adding oil will not be a safe move, could lose steering. The bleeding is not complicated, but you need a partner to do it easily. Most dealers are familiar with the systems and could make it right.

[bvs]

This depends on who made your system. Most don't use regular hydraulic steering fluid. They use a thicker oil similar to transmission fluid. Make sure you use the right stuff. Otherwise, yes, you just pour it in.

[Javelin360]

I just purchased the boat and and it did not have a manual. It is a sea star system and the fill location is behind the steering wheel on on the shaft. I took off the cap and it looked low. I was concerned about air bubbles, bleeding the line, etc. Do you know what fluid to use?

[bvs]

From my SeaStar manual (for all steering SeaStar systems except Capilano):

Recommended: SeaStar Fluid, P/N HA5430 (1 quart).
Acceptable: Chevron® Aviation Hydraulic Fluid A, Esso® Univis N15 or J13, Mobil® Aero HFA, Petro Canada Harmony HV115 (in Canada only), Shell® Aero Fluid #41, Texaco® HO15 and other fluids meeting MIL SPEC H-5606-G.
Emergency: Dextron II tranny fluid, but it voids the warranty.
Extreme Emergency: Any non-toxic, non-flammable liquid.

It says to fill the reservoir to the bottom of the filler hole and never let it drop more than 0.5" below. Call around. Dealers sell the SeaStar stuff for about $20/quart but I've heard the aviation stuff is about 1/3 the price if you can find a place that sells it. I've never had the patience to search.

[Javelin360]

Thanks for the info! Sounds like it is tough to find these fluids. It may be best to just take it to a marina.

[staylor]

Most larger marinas carry the Sea Star fluid in quart bottles. When you fill, be careful not to overfill. The fluid level changes a bit with temperature and overfilling tends to be messy. My Starcraft came with Sea Star and a remote fill fitting- a hose was run to the reservoir and run upward to the dashboard. very easy to fill and I promptly filled to within a half inch of the top of the fill fitting on the dash. I had never seen a Sea Star before and thought I was being diligent. I filled in the spring at about 55 degrees, and the first time the temps got to 80 degrees I had quite a bit of fluid come out of the fill cap and dripping on the carpet. Luckily I caught it before it spread too far, although my carpet under the spill isn't firmly glued to the deck anymore- the fluid must have dissolved the factory glue. Now when I check the lvel I slide under the dashboard and look for the fluid level in the hose to the reservoir to be about 2 inches above the reservoir. The hose is about 14 inches long and this appears to leave enough empty hose for air expansion. I haven't needed any fluid in the last 3 years. You need the manual for the instructions on how to bleed the system and how to adjust the attachment nut to the motor to take out slack. If you just push the motor's cav plate back and forth on the trailer by hand you can see how much free motion you have. Ideally, the attachment rod at the motor end should have less than 1/4 inch play- less than 1/8 inch if you really bleed the heck out of the system. The slack adjustment nut needs to be re-adjusted at least once per season- I do mine twice a year- a 5 minute job.
Doug