The exhaust in a semi-truck consists of various parts and devices that help to remove the gasses from the engine to reduce the engine noise and improve its efficiency. The exhaust gets hot because of the high temperature of emission gasses coming from the engine. The temperature of the tailpipe increases because gasses move straight from the engine.
How Hot Does a Semi-Truck Exhaust Get? Semi-truck exhaust becomes hot and reaches 500 to 800 degrees Fahrenheit under normal conditions. However, it can also reach up to more than 1000 degrees Fahrenheit depending on the engine speed, heavy loads, and engine conditions. It gets extremely hot and reaches a temperature of 1200 to 1600 degrees Fahrenheit because of uphill driving, city areas, and idling for longer.
When you start idling, the exhaust manifold temperature remains at 300 degrees Fahrenheit because of the decreased engine speed and low RMPs. It becomes high when you accelerate and increase the speed, corresponding to a higher RMPS with a greater load.
You can see the temperature rises to 800 degrees Fahrenheit. I was driving my semi-truck and hauling heavy cargo. I realized the high temperature from the exhaust manifold and emissions. You can use an infrared thermometer to check the temperature and position the device over the weld ring where the inlet pipe is connected to the converter body.
How hot does an exhaust manifold in a semi-truck get?
Exhaust manifolds usually get hotter because emission gasses move directly from the engine to the tailpipes. The temperature of the emission gasses is high because of the internal combustion engine and the burning of air and fuel mixture.
It remains at 300 to 400 degrees Fahrenheit when you start your truck. It is normal at the start of the idling because of the low engine speed and RPMs. However, it increases up to 500 to 800 degrees Fahrenheit when you accelerate the vehicle to gain speed.
Sometimes, it becomes more than 1000 degrees Fahrenheit under certain conditions. It becomes extremely hotter when hauling heavy loads. Moreover, commercial vehicles have high exhaust manifold temperatures because of the powerful engines that produce emissions at a greater rate.
They become hot in the range of 1200 to 1600 degrees Fahrenheit because of the continuous idling, blocked engine filters, high engine speed, and continuous driving on the road.
When does the exhaust manifold get too hot in a semi-truck?
The exhaust gets hotter and reaches a temperature of 1200 to 1600 degrees Fahrenheit in certain conditions. The extremely high temperature needs to be countered because it increases the risk of damage to the engine and exhaust parts, which negatively affects the truck’s performance.
Uphill driving
My friend faced this issue while driving his truck over inclined road surfaces. The engine requires more power to haul the vehicle on steep roads because of the sloppy surfaces.
The engine produces more power and releases emissions at a higher rate. The temperature of the emission gasses increases because of high engine speed and RPMs that are required for uphill driving.
High-temperature emission gasses, when passed through the tailpipe, make them hot and also increase the risk of cracking and corrosion.
Driving in city areas
Commercial vehicles, including semi-trucks, are restricted in city areas because of their larger size and heavy hauling, which can affect the traffic on the road and pose serious safety hazards to smaller vehicles.
However, you can drive them in stop-and-go traffic and city areas during certain times and conditions. Driving in city areas negatively impacts the engines of these commercial trucks.
Their engines are heavy and are specially designed for smoother and highways roads. Engines produce more emissions when you drive them in stop-and-go traffic, increasing the exhaust manifold temperature to more than 1000 degrees Fahrenheit.
Towing heavy things
Commercial vehicles, including semi-trucks, have larger trailers for heavy hauling. You can load the cargo on the trailers to transport them to different places.
My neighbor was a truck driver and he said his vehicle’s parts usually get hotter during heavy pull. He said he prefers to take short stops and allow them to cool to reduce the risk of their damage.
Idling for long
The engine takes more power when you start it frequently. Drivers also leave their trucks in idling when they wait at truck stops.
The engine of your vehicle remains running at low RMPs and produces the emission gasses at a lower rate, which raises the temperature. However, the temperature increases when you leave it idle for longer because of the continuous emission of hot gasses.
Moreover, you can also face issues because of the leakages of the internal combustion procedure that regulates the combustion procedure because of fuel leakage. The engine does not stop and cool down, which causes the problem.
When does the high exhaust temperature light illuminate in your semi-truck?
Sometimes, exhaust manifolds get extremely hot in ranges of 1200 to 1600 degrees Fahrenheit. A high exhaust temperature warning light illuminates to warn the drivers when the temperature increases.
The light illuminates intermittently according to the changes in temperature. In addition, light also comes on the screen when DPF reaches more than 800 degrees Fahrenheit.
The light most often illuminates when the engine completes the regeneration process. In addition, HEST light also comes on the screen because of clogged diesel particulate filters, which leads to overheating.
What happens when the exhaust gets too hot in a semi-truck?
Overheating of exhaust components causes several issues that can affect normal driving and smooth engine performance. Heat also directly affects the engine parts and the efficiency of the combustion.
It can damage the catalytic converters and increase the overall environmental pollution.
Failed catalytic converters cannot convert the toxic emission gasses to their less toxic form. Moreover, overheating also leads to corrosion of metal parts. It can also damage the muffler and tailpipes of the system.
It increases environmental pollution by releasing more nitrogen oxide and hydrocarbons. Higher temperatures can also lead to poor fuel efficiency and decreased fuel economy.
It can also cause safety concerns by increasing the risk of fire hazards. Hot surfaces and the presence of combustible material can pose a fire hazard. You can hear the excessive noise from the engine because of the damaged muffler, which absorbs the noises of the engine and emissions gasses.
How do you prevent the semi-truck exhaust from getting hot?
You can decrease the overall temperature by wrapping the exhaust manifold with an insulation layer.
The insulation layer reduces the overall heat and prevents components from high temperatures. I also wrapped my truck hood parts with fiberglass insulating material, which decreased the heat to 50%.
My friend said he also faced this issue in a semi-truck because it is a commercial vehicle and used for heavy hauls. He told me he used the radiant heat shield over the engine components because it deflects the heat away and keeps treated parts at normal temperature.
It is the aluminum or steel sheet that is 2 to 3 centimeters away from the exhaust manifold to dissipate heat.
You can also use the thermal insulation on various heat sources, including turbocharged mufflers, tailpipes, downpipes, and headers.
In addition, it is also better to avoid overloading because it increases the engine power.
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