How Hot Does an Exhaust Manifold Get?
Author: SPELAB Mechanical Engineer (focusing on car modification for 10 years)
To ensure that your vehicle works fine and gives stellar performance, the exhaust system along with its various parts including the exhaust manifold, is extremely important. When an exhaust system fails, it leads to lack of acceleration power, decrease in fuel economy and also irritating noises and smells.
How hot does the exhaust manifold get?
Absolutely, when those gases exit the engine, they're super hot. Near the cylinder heads, the exhaust manifold can hit temperatures of about 1,200 degrees Fahrenheit. That's some serious heat!
Why does the exhaust manifold get hot?
The part belongs to an automobile exhaust set consisting of a tailpipe, exhaust pipe, muffler, lambda sensor, catalytic converter, resonator, and exhaust manifold. The primary function of the manifold is to reduce exhaust fumes, save fuel, and lower noise levels. There could be a handful of reasons why the exhaust manifold becomes hot. Take a look:
- Defective gas-pressure regulator.
- Retained ignition timing.
- Leakage of the air-line.
- Problems with the exhaust valves or inlet.
- Broken or damaged turbocharger.
- Bad injectors or nozzles.
- Poor governor setting.
- Blocked catalytic converter.
- Incorrect injector setting/ valve-lash adjustment.
- Blocked exhaust gas recirculation (EGR) valve.
Let’s understand some basics about exhaust manifold and how a problematic exhaust manifold can give you bad driving and maintenance experience.
What is an exhaust manifold?
To ensure your vehicle has sufficient power, it burns fuel. This process releases toxic gases into the air. The main purpose of the vehicle’s exhaust system is to cool the gases down to a safe temperature and clean them. Once they're prepped for release, the exhaust system expels them through the exhaust pipe.
Image credit: https://www.autoguru.com.au/
There are numerous parts of an exhaust system that function as a team to get the job done, such as the manifolds, catalytic converter, heat shields, joints, tailpipe, flexible unions, mufflers, and more. The parts endure harsh conditions like high temperatures, so they require regular maintenance. They are even prone to becoming worn-out a lot faster than other vehicle parts. Exhaust manifolds are typically made out of cast iron or stamped steel to help them withstand extreme temperatures.
In case there is a leak in the exhaust system, dangerous and harmful gases could start seeping through the cabin of your vehicle, instead of being dispersed outside. Not only does this put your health at risk, but your vehicle won’t be performing as well as it should.
Image Credit - https://www.benzworld.org/
What are the signs of a problematic exhaust manifold?
If there is an exhaust manifold leak, there will be signs that indicate trouble. Here goes:
Loud sounds
If there is a hole or lost gasket between any parts of the exhaust system, the escaping sound and pressure would lead to loud noises. However, manifold damage tends to create either hissing or tapping sounds centered on the back of the engine bay. You might also hear a weird noise like rocks tumbling or a loud grinding if the catalytic converter gets damaged due to the manifold’s malfunctioning. These sounds indicate the vehicle’s engine isn’t holding proper compression any longer. Get your vehicle to the exhaust shop immediately, to prevent the heat build-up from damaging other parts of the fuel and exhaust system.
Burning odor
Do you smell an unpleasant odor of burning plastic or rubber upon lifting the hood of your car after a drive? The exhaust manifold gaskets have coatings that smell like rubber or plastic when they get overheated and burned. Damaged manifolds fail to transfer the heat like they are supposed to, which causes issues and compounds exhaust leaks.
Performance issues
Yet another sign that the vehicle is having exhaust issues is a slow or sudden loss of power when accelerating. You might notice that the car doesn’t take off the way it used to from a stoplight, or that you have to press the pedal much harder just to reach the next gear. A loose manifold or one with a damaged exhaust manifold gasket slowly affects acceleration power.
Poor fuel economy
Fuel efficiency goes down when the manifold is damaged because the exhaust isn’t staying pressurized properly. Not only does this lead to loss of power, but the car burns more fuel to cover the same distances. A new gasket or manifold could pay for itself in fuel savings within just a few months.
Image Credit: https://carfromjapan.com/
Visible damage
Inspect the manifold from all sides, after any of the aforementioned symptoms occur. You might notice a visible crack in the metal – it could be hairline thin where the part is pressed against the engine, so don’t rule out a manifold problem just because you can’t spot visible damage.
Don’t ignore any signs that indicate exhaust system issues. If you neglect the issue, it could become a major problem later on, and you might have to pay an exorbitant amount to fix the damage.
