The Common Car Tool You Should Never Buy Cheap

As reported in multiple articles on this website, many times the cheaper tools sold by Harbor Freight are the ones you can count on to get the job done and at a much more affordable price than most name brand tools.

Related article: Tools Every Mechanic Must Own

However, this is not always true with every tool.

Especially when the cheaper tool does not just fail but causes additional damage that exceeds the savings from buying the cheaper priced tool brand.

One example is that of flare nut wrenches.

What is a Flare Nut Wrench?

A flare nut wrench, also known as a line or tubing wrench, is a specialized tool used primarily for working with flare fittings or hydraulic fittings. Rather than having a completely boxed end for grasping a nut, the end is slightly open serving two purposes:

1. It allows you to slip a wrench over a fuel or brake line that a boxed end wrench cannot get to.

2. Has more surface area than a typical open-end wrench, which means there is less chance of the wrench slipping and damaging the nut’s edges.

Why Is a Flare Nut Used?

A flare nut is a specialized nut used to secure a flared tubing’s tapered end to a matching tapered fitting that produces a leak-tight seal that can withstand a significant amount of pressure―which is what a fuel line or brake line needs to avoid leaks and/or line failure.

Because a flare nut is in-line with the tubing to its mating part, a special wrench called a flare nut wrench with its slightly open end is typically used.

Why Can’t I Use a Regular Open End Automotive Wrench on a Flare Nut?

You can; however, flare nuts and other connectors used in brake or fuel lines―or other types of connected tubing―are typically made of softer metal than the nuts and bolts you use with a regular open or boxed end mechanic’s wrench.

Because the nuts or connectors are relatively soft, the opened end wrench with only 2 sides making forcible contact on the flare nut can slip on the nut’s edges and damage the nut making the repair or service more difficult and expensive. A flare nut wrench on the other hand has more surfaces that apply force to the nut’s edges and thereby is less likely to slip under torque pressure when wrenching a stubborn flare nut or other connector.

Are Flare Nut Wrenches a Better Wrench than a Regular Wrench?

In most cases, the flare nut wrench is superior to a regular box or open-end wrench only for the job they are specifically designed for. While a flare nut wrench will fit over the same nut a boxed end wrench can, sometimes the use of the open-end wrench is needed because of space limitations that prevent the use of a flare nut wrench or boxed end wrench.

 Reasons for Not Using a Flare Nut Wrench on a Nut or Bolt

As mentioned earlier, a flare nut wrench’s working end will not always be able to access a nut or bolt head because of space limitations. However, other reasons not to use a flare nut wrench on anything other than a flare nut or similar connector are due to:

• The flare wrench is a specialty tool. Every time you use it, you weaken it. Flare wrenches should only be used for the job intended.
• Not all flare nut wrenches are good quality. Unless you are sure of its quality and performance capabilities from reviews, using a flare nut wrench when it is not really needed is risky…and a bad overall tool habit to have.
• Sometimes an open-end wrench will do a better job on a flare nut when it comes to the larger sized flare nuts of 5/8-inch or bigger as recently shown in the video below.

An Important Flare Nut Wrench Tool Review

To see just how important buying the best flare nut wrench you can afford, here is a useful flare nut wrench tool review from the Project Farm YouTube channel that reveals just how much a tool set of these types of specialty wrenches vary in both performance and price…which turns out are not always correlated.

Are Flare Nut Wrenches Any Better? Let's Settle This!

Which Flare Nut Wrench Should I Choose?

Overall, a flare nut wrench is a valuable tool for anyone working with flare fittings on their car’s fuel or brake lines because they offer a better grip, higher nut-fit precision, and the ability to work in tight spaces without damaging the fittings.

And while the host pointed out three top performers rated in his personal order of preference based on mostly price since all three were closely similar performance-wise, I would have to bite the bullet and go ahead with the pricey Snap On tool at $285 for a set over the host’s preference for the $75 Proto brand set of flare nut wrenches.

The reason for this is largely because the Snap On flare nut wrench is significantly smaller in size making it easier to fit into tight places―which is often the case with fluid and brake lines. Human nature being what it is, if a recommended wrench on hand does not fit because it is too big for the space used, there is the temptation to go to the wrong tool.

Going to the wrong tool increases the risk of doing damage to the part and winding up paying even more in the long run than if you had just paid more earlier on for a better fitting tool.

When you mess up a flare nut, you might easily wind up having to replace the entire line which is going to get expensive if it’s a job you have to have a garage do for you.

For additional tool review related articles, here are three for your consideration:

• Don’t Buy This Tool Mechanic Warning
• How Harbor Freight Did in a Best Mechanics Tool Set Review
• Best Flex Head Ratchet

Timothy Boyer is an automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on  “Zen and the Art of DIY Car Repair” website, the Zen Mechanic blog and on Twitter at @TimBoyerWrites  and Facebook for daily news and topics related to new and used cars and trucks.

COMING UP NEXT: Never Trust a Mechanic Who Tells You This

Image source: Deposit Photos