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Hydraulic systems are a must for any car shop, but like with any equipment, you’ll have to replace some hydraulic fittings eventually.

Hydraulic fittings keep fluid within the system, connecting the hydraulic hose to other components (cylinders, pipes, or tubes). These fittings must fit tightly to prevent any leakage in the hydraulic system. If you’re working on your hydraulic system and need to replace your fittings, you may need advice about which ones to purchase. There are many different hydraulic fitting types, each with varying sizes of tread, sealing types, and purposes. We’ll help you identify the various types of hydraulic fittings so you can understand which one is best for your project.

How to Identify Different Types of Hydraulic Fittings

Identifying Fitting Type: Reusable or Permanent

The first step in determining which type of hydraulic fitting you need is to understand whether you need a permanent or reusable fitting. Most hydraulic systems require permanent hydraulic fittings, which are much more common than reusable fittings.

Permanent hydraulic fittings need an attached hydraulic crimper on the hose. Because of this, permanent hydraulic fittings are also referred to as crimped fittings. These crimped fittings are easy to assemble and are known for their reliability in the hydraulic industry. In addition, mobile technicians and even onsite mechanics can use portable hydraulic crimpers. So it’s no surprise that permanent hydraulic fittings are the go-to choice for hydraulic systems.

While permanent hydraulic fittings connect to hoses using a crimper, reusable fittings use a vice and a wrench. Reusable fittings have steel bodies with brass components and are also known for their reliability and resistance to corrosion. Reusable fittings are best for low to medium-pressure applications. However, they are less widely used than permanent hydraulic fittings because of their time-consuming process and higher costs.

Match Connections and Fitting Ends

Once you’ve identified whether you need a permanent or reusable hydraulic fitting, you’ll need to determine which connector type and fitting end you’ll need. The port connection needs to match that of the hose.

Some common connector types and hose combinations are listed below:

• BSPP (JISPF) and 60-degree NPSM Swivel
• BSPT (JIS-PT) and 30-degree Flare (Metric)
• DIN Metric and O-Ring Face Seal (ORFS)
• ISO 6149 and 24-degree Flareless (DIN)
• JIS-B2351 and 30-degree Flare (BSPP)
• Metric Taper and 45-degree Flare
• NPT-NPTF and 37-degree Flare
• SAE Straight and 24-degree Flareless (SAE)

Identify Fitting Sealing Type

Once you’ve determined your connector type and fitting, you’ll need to identify the sealing method, which usually consists of an O-ring, automated angle, or tapered threads.

Mated angle hydraulic fittings have either straight or parallel threads for sealing. While the male and female counterparts thread together, the seal is formed when the two mating angle seats are brought together. Examples of standard mated angle fittings are SAE 45° and JIC 37°.

If you need a fitting for high-pressure applications, you’ll likely need an O-Ring Face Seal or ORFS. This type of hydraulic fitting is known for its reliability and security, eliminating leaks in hydraulic systems with pressures up to 6,000 PSI. There are a few different types of ORFS fittings, including:

• Straight ORFS
• Cross ORFS
• Elbow ORFS
• Tee ORFS

The straight ORFS fitting is a straight screw connection with a male connection point, while the cross ORFS fitting has four male connection ports. The elbow ORFS fitting has a male and female connection at an angle, and the tee ORFS fitting has two male ports and one female port. 

Other less standard hydraulic fittings include the DIN (Deutsches Institut für Normung) and BSP (British Standard Pipe). DIN fittings are often interchangeable with different brands and are used across various industries. BSP fittings are popular in the plumbing industry in Europe.

Identify Thread Size and Fitting Design

While figuring out which thread to use might seem overwhelming, the following steps can help you identify them.

Determine if your thread is tapered or parallel.

Visual inspection alone is often enough to determine whether your thread is tapered or parallel, as tapered threads get smaller toward the end of the fitting, while parallel threads stay the same size. However, if it’s not apparent, you can use a caliper.

NPT/NPTF and BSPT are tapered threads, while UN/UNF and BSPP are parallel.

Measure the pitch

Use a pitch gauge to determine the number of threads within a specified distance. Most threads have a distinct pitch.

Determine the size

Determining the thread size is relatively simple, depending on whether it’s a pipe thread. If it’s a pipe thread, compare it with a nominal-size profile (or for pipe sizes smaller than 2 inches, you can measure the outside diameter and then subtract a quarter inch).

For non-pipe thread, measure the outside diameter with a caliper. 

Once you’ve completed the above steps, you’ll know what type of thread you’ll need, whether it’s NPT/NPTF, BSPT (JIS-PT), SAE Straight Thread, or ISO 6149, JIS-B2351, BSPP (JIS-PF), or 4-Bolt Flange.

Ensure Quality Hydraulic Connections and Fittings with SVI

Every vehicle has a fuel pump that moves fuel from the gas tank to the engine. Not only is the pump responsible for moving the fuel to the engine, but it also regulates the pressure.

A failing fuel pump can cause significant issues to a vehicle’s drivability and performance, including the car’s inability to start. However, most fuel pumps are designed to last the vehicle’s lifespan, so you generally will only have to replace them after you hit 100,000 miles.

We will discuss the differences between a mechanical vs electric fuel pump and the uses and benefits of both types.

What Are The Differences Between a Mechanical and an Electric Pump?

Mechanical Pump

If your shop works on many older vehicles, you’re probably familiar with mechanical pumps. Older cars have mechanical fuel pumps powered by a crankshaft and driven by a motor. A small arm moves, which tightens and loosens the pump’s diaphragm, creating the vacuum that powers the pump. These older cars need the mechanical pump near the engine driving the crankshaft, which is less flexible than electrical pumps.

In some applications, mechanical pumps are being replaced by electric fuel pumps because of their pressure threshold. Mechanical pumps are limited to a pressure of up to 6 psi, while electric pumps can operate with pressures of up to 40 psi. However, older cars and equipment aren’t generally built for the high-pressure output from electric pumps, so mechanical pumps may still be the right choice for older vehicles.

Mechanical fuel pumps are known for being reliable, quiet, easy, and perfect for older engines with carburetors. However, one drawback to mechanical fuel pumps is the possibility of vapor lock in the fuel line. Vapor lock, when fuel turns into vapor before it reaches the pump, happens when the engine or exhaust system gives off excessive heat. If this happens, the car will stall, and you may have problems restarting the engine.

Electric Pump

Newer vehicles use an electric fuel pump because they have direct fuel injection systems instead of a carburetor. The electrical pump’s higher pressure is perfect for this application.

Because electric pumps use electric power, they can be located in the fuel tank, which is much more flexible than a mechanical fuel pump. In addition, the position of the electric pump eliminates any possibility of a vapor lock, which is a significant benefit.

Like mechanical fuel pumps, electrical fuel pumps are simple and reliable. However, replacing them can be difficult, as you must drain and remove the fuel tank. In addition, many times, electric fuel pumps have ineffective filters, with no way to change them easily. Other potential issues include the likelihood of rust or sediment in the fuel and prolonged heat exposure diminishing the pump’s lifespan.

Additionally, a significant drawback of electrical fuel pumps is the fire risk due to an unknown leak. Therefore, if you smell fuel or hear whining from your tank, it’s imperative to inspect it immediately.

Best Uses for a Mechanical Pump

Best Uses for an Electric Pump

Almost all newer models of cars with a fuel injection system require an electric fuel pump. However, because of the higher pressure of an electric pump, you’ll likely need a fuel pressure regulator.

Cars with engines above 450 horsepower and up to 2,000 horsepower will need an electric pump. Other options include belt-drive fuel pumps and an EFI sump, but unless you’re dealing with extreme-performance sports cars, you likely won’t need to consider these.

What Should My Fuel Pressure Regulator Be Set At?

When deciding between a mechanical vs electric fuel pump, you may want to consider the need for a regulator. If you have a mechanical pump, you don’t need a fuel pressure regulator, but all fuel-injected vehicles require one. A regulator ensures that your fuel injectors or carburetor receive the proper fuel pressure.

While every system is different, some standard settings are:

• Carburetor/Mechanical Pumps: 6 PSI
• Fuel-injection system/Electrical Pumps: 40 PSI
• While these are standard suggestions, verifying with your manufacturer is always best.

What Fuel Filter Should I Use?

When considering a mechanical vs electric fuel pump, you should also consider the required fuel filters. Mechanical and electrical fuel pumps require different fuel filters. While a mechanical fuel pump will do well with an inline fuel filter, electric fuel pumps also need a pre-filter.

Mechanical pumps usually need a 40-micron filter as the inline fuel filter between the carburetor and the pump. However, most mechanical fuel pumps don’t require a pre-filter, an added benefit.

On the other hand, electrical pumps require a pre-filter, such as a 100-micron filter. The recommended post-filter is 10 microns to protect the fuel injectors adequately.

Some filters also have a built-in regulator, which can be an excellent all-in-one solution.

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