What Are Car Exhaust Manifold Bolts Made Of? (Answered)

All car exhaust manifolds need to be connected to the car with bolts to keep them securely fastened at their position.

But what are the car exhaust manifold bolts made of? Are they rust-proof? Can they easily break?

Let’s find out questions to these answers in the below article.

Here Are What Car Exhaust Manifold Bolts Are Made Of

Car exhausts manifold bolts are typically made of metal. On older vehicles, the bolts are usually made of iron, but most modern vehicles, as well as aftermarket exhaust manifolds, have bolts that are made of stainless steel.

car twelve cylinder engine with manifold
Car twelve-cylinder engine with manifold bolts

Most exhaust bolts are made from either iron or steel. Iron is a cheaper option and is also found on most older vehicles. It isn’t as durable as steel and does not hold up as well to heat. It corrodes quickly and simply won’t last as long as the steel bolts.

Steel bolts also come in different grades. Stainless steel is the best option, and most aftermarket exhaust bolts are made of stainless steel.


Do Car Exhaust Manifold Bolts Rust? How To Avoid Them?

A rusty car bolt is usually caused by oxidation. Steel reacts with oxygen and moisture in the air to produce this result. Rust is made up of iron oxide.

Rust develops on your car’s bolts when water, salt, dirt, and oil come into contact with them. The chrome or stainless steel quickly turns into rust instead of looking like shiny metal!

Your car is continuously exposed to moisture, even if it is parked in a garage. Unlike the car’s body, the exhaust system is exposed and not well protected, which explains why rust and corrosion are common problems.

 It is constantly hit with water, salt, and other debris while driving, which can cause the exhaust pipes and mufflers to rust. Your exhaust system will stay in good working condition for a long time if you follow these steps.

There are ways to prevent rust. Maintaining your car’s cleanliness and drying it regularly, as well as applying a wax sealant to its exterior, can help prevent rust.

You can prevent water from remaining on your vehicle’s surface by regularly washing the car to remove dirt or salty residue from the road. It’s time to explain that undercarriage feature at the car wash you’ve always wondered about.

In addition to removing salt and other corrosive debris, you should also rinse the underside of the vehicle to keep it clean and prevent rust from forming on metal components.

Once or twice a month, you can wash your car yourself with your garden hose and an attachment if you don’t want to hit the car wash all the time.

Early detection of rust is key. Stop washing your car right away if you notice rust. Depending on the situation, either wash off the area or leave it alone until later.

Remove rusted bolts by hand instead of using power tools, such as an angle grinder, because this could damage other aspects of the vehicle. When rusted bolts are detected, remove them as soon as possible so that the corrosion doesn’t spread further.

Rust can also be prevented by painting the bolts. You can paint or powder coat your exhaust system, even if it sounds like it’s only for hot rodders.

The surfaces of the exhaust system can be protected and kept from being damaged by moisture and debris by applying a coating of high-temperature paint or powder coating.

Having your exhaust system painted or coated by a local exhaust or body shop virtually eliminates any weather-related issues and helps delay rust.

Can Car Exhaust Manifold Bolts Break?

Due to the exhaust temperature being constant while the car is running, the bolts can become weak and eventually break.

Despite being designed with linear expansivity in mind, after multiple cycles of expansion and contraction, these high temperatures cause bolts to expand, resulting in their weakening and eventual breakage.

The fact that the bolts are exposed to natural elements, such as humidity and water, is also a factor that causes metal to rust over time.

The bolts will rust and eventually fail after a couple of years of exposure, no matter how strong or well-coated they are.

Over time, the vibration will wear down the bolts if they are not properly fastened, resulting in their failure, ideally not while you are driving down the highway.

What Are The Best Car Exhaust Manifold Bolts?

Exhaust bolts should be made from stainless steel. These materials offer extra protection from corrosion and rust under high temperatures.

In some cases, stainless steel bolts can be corroded after some time when used in iron threads or on complete stainless steel exhausts.

Make sure you use copper anti-seize rather than anti-seize that contains graphite to prevent this.

It is possible to switch out your exhaust manifold bolts without getting an entirely new manifold, but keep in mind that stainless steel bolts are pricier than iron bolts, and the process of replacing them can also be costly if you aren’t able to do it yourself.

How Long Do Car Exhaust Manifold Bolts Last?

Manifold bolts last for various amounts of time, depending on a variety of factors. The frequency with which you use your car, the geographic location, and even the temperature.

The roads in some locations are salty and chemically laden because of snow and ice. If you live or drive in one of these areas, your exhaust manifold bolts are likely to break down more quickly.

Depending on the type of manifold and bolt material you have, there are also other factors to consider. As a result, iron bolts are less likely to last as long as steel bolts.

It’s also more likely that your vehicle’s bolts will break if you drive it off-road or on rough terrain.

Final Thoughts

While exhaust manifold bolts are meant to withstand normal driving and wear and tear, some are not made of durable materials are don’t last as long as others. Since most bolts are made of iron or stainless steel, they can also rust when they come in contact with road salt and other chemicals that are sprayed on roadways.

This means they can also break easily. To ensure your manifold bolts last a long time, choose bolts made of stainless steel and take preventative steps to keep them from rusting.


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