Wayne Cook
November 1, 2009
Photos By: Courtesy of Manufacturers

Tech | MMF Hose/Fluid Line Replacement
When we stop to think about it there are a lot of different types of fluid transfer processes that keep our Ford vehicles moving. Reliable function of these processes is imperative and any malfunction, however brief in any of them, can be catastrophic. We don't need to elaborate about what's at stake if fluid transfer for your brakes is interrupted. Almost as important are the engine oil, engine coolant, and automatic transmission fluid. Any prolonged interruption in these systems will fail the affected component.

Problems with the fuel system of course will stop the engine, but the chance of a leak is of far more concern because of the possibility of fire. Besides a careful routing plan that keeps any fluid transfer lines away from heat or moving parts, it's also important to understand that the requirements for lines and other components differ according to application. For example it would be a mistake to use low-pressure welded fuel line as brake line. Even though the system might be made to work, the fuel line won't have the same bursting pressure threshold as will purpose-designed seamless brake line, and could fail suddenly, resulting in loss of braking power.

The good news is that there are more choices than ever before when planning fluid transfer aspects of your next project. Many of the components you'll be after are now specifically made for your car. For example, if you're restoring a '68 Mustang it's possible to acquire a complete set of brake lines pre-bent specifically for your job in a choice of OE finish or stainless steel. It's also possible to find new transmission lines for popular conversions or upgrades. If you've decided to install an AOD transmission into your first generation Mustang a complete set of transmission cooling lines is now available pre-bent to the custom application and ready to bolt in. The advantages available in modern materials make other fluid transfer upgrades possible. Many classic Ford enthusiasts we know have replaced their OE-style rubber flex hoses on their brake systems with lines having a braided steel jacket. The result is less line expansion under pressure and a firmer brake pedal with more solid response.

Let's break down our discussion into some of the major categories present on any Ford vehicle. We'll then discuss options that you may wish to pursue during the fluid transfer phase of your next Ford vehicle project.

Brakes
One of the most popular areas to address on many Ford projects, especially those of a vintage nature, is brakes. Besides eliminating drum brakes in favor of disc, most brake system refurbishment projects include replacement of rusted or otherwise damaged brake line. Often custom brakes lines will need to be fabricated as well.

Transmission Lines
Manual transmissions usually don't have external coolers but automatic transmissions almost always do. Whether the transmission fluid is routed to a heat exchanger inside the vehicle radiator or to an independent cooler, not to mention the line pressure and heat from automatic transmissions, demands a failure proof system. Besides the potential for a huge mess from a line or connection failure, the transmission fluid also poses the danger of fire if sprayed onto a hot exhaust manifold. The procedure for creating your own transmission cooling lines will be the same as shown for the brake line flaring formation but using larger diameter line. As is the case for brake lines, pre-bent transmission cooling lines are very likely available for your application.

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Fuel
Fuel system requirements are very strict because of the danger of fire. Often times when a different carburetor is installed, the factory hard line is replaced with flexible fuel hose. While this can be acceptable if the length is kept in check, a safer and more sanitary fuel line routing/connection is desirable. For fuel system requirements it's hard to beat AN fittings, and honestly AN lines and fittings can be used in just about any fluid application, although fuel systems are the most popular. There are even quick-disconnect style AN fittings for easy vehicle servicing.

AN SizeTube Outside diameter
-21⁄8-inch
-33⁄16-inch
-41⁄4-inch
-55⁄16-inch
-63⁄8-inch
-81⁄2-inch
-105⁄8-inch
-123⁄4-inch
-161-inch
-201 1⁄4-inch
-241 1⁄2-inch
-281 3⁄4-inch
-322-inch

Another An Application
On most of our Fords, the engine oiling system is completely internal to the engine and doesn't require our attention. However, once we get into high-performance applications an external engine oil cooler is often desirable.

Coolant
Another critical area on your Ford involving fluid transfer is the engine cooling system. Here, unimpeded and uninterrupted fluid circulation is imperative. While OE-style rubber hoses are usually adequate, many enthusiasts we know choose to add braided steel jacketed hoses to their engine cooling system. While cooling systems operate at relatively low pressure of between 5 and 18 psi, these hoses have a greater resistance to heat and bursting and also add a custom touch to the vehicle engine compartment.

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