Hydraulic Steering Fluid: Choosing The Right Type For Your Boat

When it comes to hydraulic steering fluid for boats, there are a variety of options available. The type of fluid you need will depend on the specific requirements of your boat's steering system, as well as your personal preferences and budget. Some common types of hydraulic steering fluid for boats include:

- SeaStar/Bay Star HA 5430: This fluid meets Mil-Spec H-5606C standards and is widely used in boating centres across the United States.

- Chevron Aviation Hydraulic Fluid: This is one of the brands that SeaStar Solutions, a leading manufacturer of hydraulic steering systems, recommends.

- Esso Univis N15 or J13: Another SeaStar-approved option that can be used in your boat's hydraulic steering system.

- Mobil Aero HFA: This is another recommended option by SeaStar Solutions, ensuring compatibility and optimal performance.

- Automatic Transmission Fluid (ATF): Some boat owners opt for ATF as it is commonly used in power steering systems and is readily available. However, it is important to note that using ATF may cause issues in cold climates, making the steering stiff and requiring more effort.

- Power Steering Fluid: While some people argue that only power steering fluid should be used in hydraulic steering systems, others suggest that it is not necessary as long as the fluid meets the specified standards.

- Other Options: In addition to the above, there are various other hydraulic fluids on the market that meet MIL 5606 specifications, such as Texaco HO15. In an emergency, even 5W engine oil can be used.

It is always recommended to refer to your boat's manufacturer guidelines and seek advice from marine specialists to ensure you are using the correct type of fluid for your specific steering system.

How to add fluid to your hydraulic steering

When to Add Fluid

If your steering wheel feels loose or requires extra effort to turn, it's likely time to add some hydraulic fluid.

What Kind of Fluid to Use

It's important to use the correct type of fluid for your hydraulic steering system. The manufacturer's recommended product is always best. However, in an emergency, any oil that meets MIL 5606 specification can be used, and even 5W engine oil will work. Some acceptable brands include:

• 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

It's also important to note that automatic transmission fluid (ATF) is commonly used in power steering systems and has been used by some boat owners without issue. However, it's essential to check with your boat's manufacturer to ensure compatibility.

Step-by-Step Guide to Adding Fluid

• Thread the filler tube into the helm pump.
• Thread the bottle of fluid onto the filler tube.
• Poke a hole in the bottom of the bottle or cut off the bottom and create a funnel.
• Turn the bottle upside down, like an IV, ensuring that the filler tube always remains filled with fluid. If it drains out, you will need to start over as you will be pumping air into the system.
• Turn the steering wheel hard to starboard.
• Open the starboard bleeder nipple located on the steering cylinder.
• Turn the steering wheel to the port side, pumping air/fluid out of the bleeder fitting.
• Once you see an air-free stream, close the bleeder nipple.
• Continue turning to the port side until the engine comes hard over.
• Open the port bleeder nipple located on the steering cylinder.
• Turn the steering wheel to the starboard side, pumping air/fluid out of the bleeder fitting.
• When you see an air-free stream, close the bleeder nipple.

By following these steps, you will ensure that your hydraulic steering system is properly bled, free, and clear of air bubbles.

Recommended fluids for your steering system

The best oil to use in your hydraulic steering system is hydraulic steering fluid, which is clear, mostly odourless, and light-coloured. It is specially formulated with viscosity stabilisers, anti-wear and anti-foaming agents, and corrosion inhibitors.

It is important to use the manufacturer's recommended product. SeaStar, for example, recommends SeaStar Fluid, P/N HA5430 (1 quart), HA5440 (1 gallon). The following brands are also 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
• Aeroshell Fluid 4
• Mil 5606

Other fluids can be used in an emergency, such as 5W engine oil or automatic transmission fluid (ATF). However, non-approved fluids may cause irreparable damage, loss of steering, and cancellation of warranty.

It is also important to note that hydraulic steering fluid should be replaced every five years, and the system should be flushed and bled to remove air bubbles and any dirt or contamination.

What to do if your steering fluid is contaminated

If your steering fluid is contaminated, the first step is to identify the type of contamination. The most common causes of contaminated steering fluid are dirt, water intrusion, or a leak. Here are the steps to take if your steering fluid is contaminated:

• Check for dirt or debris in the fluid: If the fluid appears dirty or contaminated, the entire system should be flushed, and the hydraulic oil replaced. Dirt is one of the biggest causes of hydraulic system failure, as it can cause abrasion and damage to the system. In addition, ensure that the system is properly bled to remove any air bubbles that may have been introduced during the flushing process.
• Check for water intrusion: Water intrusion can cause damage and internal corrosion to the system. Take a sample of the fluid from the reservoir and check if it looks like "chocolate milk," which indicates water contamination. If water intrusion is suspected, the system must be thoroughly inspected for leaks, and then flushed with clean oil to remove any contaminated fluid that could cause future damage.
• Check for leaks: If there is a leak in the system, it could be the cause of the contamination. Check the hydraulic seals on the ram by turning the wheel lock to lock and inspecting the shaft for any fluid. Also, inspect the hoses and connections between the helm and the ram with a clean rag to locate any wetness or leaks. If a leak is found, it may be possible to tighten the fitting to stop the leak. If tightening the fitting does not work, a qualified service shop should address the issue.
• Use the correct fluid: It is important to use the correct type of hydraulic steering fluid for your boat. The manufacturer's recommended product is always the best option. However, in an emergency, 5W motor oil or automatic transmission fluid (ATF) can be used.
• Regular maintenance: To prevent contaminated steering fluid, it is important to perform regular maintenance on your hydraulic steering system. This includes an annual inspection of the system, checking the fluid level and for any leaks, and ensuring the system is properly bled to remove any air bubbles.

How to check for a hydraulic leak

To check for a hydraulic leak on your boat, you should regularly inspect your hydraulic steering system. Here are some detailed steps to help you identify and address any potential leaks:

Step 1: Annual Inspection

Begin by conducting a yearly inspection of your hydraulic steering system. Start at the helm, where the oil reservoir is typically located. Check the hydraulic seals on the ram by turning the wheel lock to lock and inspecting the shaft for any fluid. Wipe the shaft dry with a rag and repeat the inspection. If the shaft becomes wet again, the seals may be leaking and require replacement.

Step 2: Check Hydraulic Oil

Remove the vented cap from the hydraulic reservoir and examine the hydraulic oil. It should be clear, light-coloured, and mostly odourless. If the oil appears black or has a strong smell, it may be contaminated or degraded and need replacement. Contamination can be caused by dirt or debris entering the system during installation or repair work.

Step 3: Inspect for Leaks

Check for signs of fluid leakage around the helm and the steering wheel. If you notice a spongy or sluggish feeling when turning the wheel, it could indicate a hydraulic leak or air in the system. Oil does not evaporate, so if you need to add oil to the reservoir frequently, it is a sign of a leak.

Step 4: Check Hoses and Connections

Wipe the hoses and connections between the helm and the ram with a clean rag to locate any wet spots. The nylon plastic hoses that snake below decks are less exposed to the elements, but the flexible rubber hoses are more susceptible to damage. Look for cracked or brittle hoses and loose or damaged fittings, as these are common sources of leaks.

Step 5: Address Leaks

If you identify a leak, the specific course of action will depend on the source. For example, if the leak is due to worn or loose hose fittings, you may need to replace the hoses. If the end caps or glands on the cylinder housing are the issue, you may need to service or replace them. Always refer to the manufacturer's recommendations and consult a certified marine technician if you are unsure.

Where to buy hydraulic steering fluid

When it comes to purchasing hydraulic steering fluid for your boat, there are several options available to you. Here is a list of places where you can buy hydraulic steering fluid, along with some details about each option:

Online Retailers:

• Amazon: Amazon offers a wide range of hydraulic steering fluids from different brands, including SeaStar, Dometic, Quicksilver, and Sierra. You can find various pack sizes, from single quarts to four-packs, with prices ranging from $26.99 to $96.68.
• EBay: eBay also offers hydraulic steering fluid, with prices starting at $15 for a quart.

Marine Supply Stores:

• Wholesale Marine: This retailer, available on Amazon, offers SeaStar hydraulic steering fluid with prices starting at $29.99.
• West Marine: West Marine is a marine supply store that provides a range of boating products. They offer discounts of up to 4% for BoatUS members.

Boat Centers:

SeaStar hydraulic steering fluid is reported to be prevalent in most boating centers across the United States.

It is always a good idea to check with your local boat supply stores and marine centers, as they may have the hydraulic steering fluid you need in stock or can order it for you. Additionally, some boat manufacturers or dealers may also offer specific recommendations or sources for the required hydraulic steering fluid.

Frequently asked questions