February 15, 2022

Can You Reuse Head Bolts?


Head bolts are a crucial part of the engine responsible for sealing the head gasket correctly as well as clamping the cylinder head to the engine block. Many different shops and individuals resume head bolts without thinking twice about it, and some engines end up running for thousands of miles, while others fall apart during the test drive. So, why does that happen, when to use head bolts again, when to replace them with new bolts, or even head studs? Let’s break it down.

What Are Head Bolts?

Again, head bolts are the bolts responsible for sealing the head gasket and keeping the engine together. Head bolts are made out of different steels and they’re heat-treated to be able to withstand tremendous amounts of pressure. However, not all head bolts are the same, and this is where the confusion comes in regarding the question of can you use head bolts again after taking them out of the engine.

There are two types of head bolts, torque-to-angle (TTA) and torque-to-yield (TTY) bolts. Both types are installed in a similar fashion, by being torqued down to a certain specification and then they’re rotated to a specific degree. This ensures that the clamping force is spread out evenly, preventing head gasket leaks and even engine warpage. The difference isn’t easily noticeable, and many repair shops, as well as individuals, confuse the two, causing major engine issues soon after. Let’s check out the difference between single-use and multi-use head bolts so we can avoid blowing up our engines.

Here You can also Read: TrackTech Products 101: Fasteners, Gaskets, and More

Torque to Angle vs. Torque to Yield Bolts: What’s the Difference?

Every fastener, or a bolt, can be stretched to a certain point, which is known as the yield point. Once the fastener has been stretched to yield, it permanently loses its elasticity.

Torque-to-yield bolts are tightened, and stretched out to their yield point, which means that they don’t return to their original size once you unscrew them; they’ll keep their elongated shape.

Torque-to-angle bolts are not stretched to their yield point, which means that they’re reusable since they usually return to their original shape; the keyword being “usually”. If you plan to reuse TTA bolts, make sure to do a thorough inspection of their overall conditions, their length, and the threads. — If even the slightest detail looks off, we highly recommend replacing the bolt.

Manufacturers can opt to use either TTA or TTY bolts since they’re very similar, if not the same, in terms of performance and reliability. However, if you’re looking for much more reliability, and fasteners that can support serious power boosts, head studs are what you need.

What Are Head Studs?

Head studs are preferred in performance applications because of their simplicity, reusability, and clamping force. Other than being an excellent support modification, head studs will make any engine much more reliable than it was before. But, are they really that much better than head bolts?

By torquing a head bolt down, you’re causing clamping force as the bolt pulls tighter against the cylinder head. However, by torquing down the bolt, you’re twisting it, causing another force onto it, which can easily result in false torque readings. Manufacturers use equipment rarely available to repair shops and individuals to avoid this issue.

Read about:5 Signs of Head Gasket Failure

Head studs clamping force is spread throughout the axis of the stud because it’s the nut that’s twisted onto the shaft instead of the entire bolt being twisted into the engine block. That exact reason is also why you can reuse head studs three-four times without having to purchase brand new ones. Engine disassembly and inspections become much easier and simpler with head studs, but once you install them, you probably won’t have to disassemble the engine ever again.

All in all, TTY head bolts cannot be reused, TTA bolts can be reused but you have to be really detailed with the inspection of the bolts, and head studs can be used multiple times without a problem.

When Can You Reuse Head Bolts?

We’ve established that the best head bolts to reuse are torque-to-angle bolts, and the manufacturer should let you know which type of bolts your vehicle has, most likely through the owner’s manual.

Before beginning the inspection, you should prepare the bolts by cleaning them from any debris. Remember that if they’re even slightly rusty (potentially caused by a blown head gasket) you will have to replace them with brand new bolts.

Now, once they’re clean, the first step of checking whether or not you can reuse the head bolts is measuring their length. It would be excellent if you already had a bolt that was never used for comparison, but if you don’t, you’ll have to search online for the exact head bolts’ specifications. Once you’ve found the specifications, use a reliable measuring tool and measure out each bolt. Keep in mind that if the bolt is even 1/32” inch longer than it should be, it’s still way off, so remember the old saying “measure thrice, check twice, cut once”.

The second step of checking if you can use head bolts again is to inspect the threads, as well as the shaft. If the threads are off or damaged, even by the slightest bit, or if the shaft seems damaged in any sort of way, that’s when you have to use brand new head bolts. While you’re at the threads, measure the width of the bolt, and make sure that it’s as close to the manufacturer’s specifications as possible.

Only after you’re completely certain that each head bolt is in perfect condition should you proceed with the installation. Even still, risking damaging the engine isn’t worth the money saved and we always recommend buying brand new ones. So, if you’re looking for strength, quality, and simply put the best head bolts on the market browse through our website to find what you need!

How to Reuse Head Bolts?

If you’re confident that your head bolts are in good shape and that you will end up reusing them even besides the many horror stories, here’s what you’ll need to do.

Grab a container, fill it up with engine oil and soak the bolts for roughly 24 hours. The oil is used to coat every part of the bolt. Next, you should clean up the bolt holes in the cylinder head as well as the engine block, and you should clean up the threads of the bolt holes. To do this, you can use a tap and die set, however, make sure that the tap doesn’t affect the threads in any way by using the correct size.

Once everything’s prepared and aligned for head bolt installation, check the owner’s manual for the correct way to torque the bolts. The bolts will have to be installed in a certain manner, usually from the middle bolts towards the outside bolts. You will also most likely have to torque the bolts in rounds, for example, each bolt to 35 lb-ft, then to 65 lb-ft, and then completely tightening the bolts to 75 lb-ft.

The Best Head Bolts and Head Studs

The best head bolts you’ll find are usually at around 160,000 psi, the best head studs are at around 200,000 psi, but TrackTech’s head studs are the strongest in class, able to withstand up to 240,000 psi.

We strive to improve our bolts and studs every day and stay a step ahead of the competition. The best is what we want to be known for, and that’s why we create our studs and bolts from the strongest alloy on planet earth.

Our fasteners are able to withstand incredible pressures under our UTM tensile testing machines. We also test our fasteners on the track by having professionals and amateur racers put their Powerstroke, Cummins, and Duramax engines with our fasteners to the ultimate performance test.

The Final Word

There are two types of head bolts, TTY and TTA. Torque to yield bolts shouldn’t be reused, while torque to angle bolts can be reused, but it’s not the best idea. However, many have reused both types successfully, but many have also ruined their engines. Saving a few hundred dollars and risking blowing up the engine really isn’t the best idea, on top of that, a brand new set of head bolts, or even better, head studs, will elongate your engine’s life by thousands and thousands of miles.

If you’re looking for the best head bolts and head studs look no further than TrackTech®. Our fasteners are track-tested and proven to provide ultimate performance and durability.

Here You can also Read: TrackTech Products 101: Fasteners, Gaskets, and More

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