What Causes High Exhaust Temperatures In Diesel Engines [10 Reasons]

Too much fuel and not enough air in the cylinders of a diesel engine results in high exhaust gas temperatures.

Allow more clean air to flow into the motor and reset the optimum air-to-fuel ratios, resulting in more efficient fuel use and lower exhaust temperatures.

10 Main Reasons For High Exhaust Temperature

1. Poor fuel treatment or quality

Before utilizing bad gasoline, you should have it serviced. That is why sending a sample of HFO or MDO to a laboratory for testing is critical.

Based on the test findings and how much temperature to maintain throughout purification, you can figure out how many temperatures and viscosities to keep.

2. Fuel valve/ Injectors

When the apertures in the fuel valve nozzles are widened, there’s a chance that too much fuel will enter the combination chamber.

These fuels may go unburned or burn at the exhaust manifold, resulting in greater temperatures than necessary.

3. Fuel Pump and Delivery valve

If the high-pressure fuel supply pump or its delivery valve fails, surplus fuel may be forced into the fuel valve, resulting in high exhaust temperatures or excessive smoke from the funnel.

4. Engine Timing setting

If the engine timing settings are incorrect, the engine’s operating condition will be inaccurate. As a result, it is critical to establish an appropriate or suggested time.

5. Increase in load

The higher the load, the more fuel supply, combustion, and exhaust outlet for the primary ship propulsion engine or main auxiliary engine.

Read More:  Does a Cold Air Intake Make Your Car Louder? Understanding the Acoustic Impact

While loads grow, if all systems are in excellent working order, the temperature will remain at the appropriate level.

6. Valve seat damage

Blow-by occurs when a leak in your valve seats or head during compression and combustion.

Place a pressure sensor on the indicator cook and slowly crank the engine to discover the unit in question. If the pressure rises and falls quicker than expected, look for leaks in the valves.

7. Air Supply to T/C insufficient

T/C are meant to suck air from the outside. However, if a second blower is fitted to deliver air to the turbocharger, it will be easier to maintain airflow.

8. Clogged turbocharger

The combusted gas may find it harder to flow through your nozzle rings if there is greater carbon buildup. Blowing out gas may not be enough if the blades are worn out or clogged.

9. Scavenge and exhaust manifold clogged

You should constantly follow cleaning regimens for the T/C air cooler and manifold inspection, which will enable more booster air entry and, if the exhaust is clean, flow out.

10. Scavenge Air leakage

When there is leakage after T/C, air delivery to the main manifold may be reduced, resulting in less outflow and a higher temperature.

Exhaust Gas Temp Management

Are you experiencing high temperatures in your exhaust? You can watch this video on YouTube to learn more about Exhaust Temperature Management:

YouTube video

The video starts with why the exhaust gas temperature (EGT) has to be monitored.

The host answers this question by mentioning that the exhaust temperature is not the main concern in this situation but the condition within your vehicle’s combustion chamber.

Read More:  P0430 Code [Causes, Symptoms, Diagnosis, and Fixes]

Other topics in this video include the difference in tuning Diesel & Gasoline engines, measuring your EGT, EGT data setup, thermocouple fitment, what high EGTs do, and much more.


What does high exhaust temp mean?

The HEST Lamp lights signal that high exhaust temperatures may be present after treatment regeneration. When this lamp is turned on, make sure the exhaust pipe outlet isn’t pointed at anything that can melt, burn, or explode.

How hot is too hot for diesel exhaust?

Any engine that runs at 1,800° to 2,000° EGT for more than a few seconds should be serviced every season since it may cause damage to the turbocharger, cylinder head, or pistons.

How Do I Control EGT?

In a diesel engine, the most frequent technique to increase power is to add fuel, and this extra fuel produces heat.

Larger turbochargers, aftermarket intercoolers, and water injection can be used to regulate it, although these items can cost thousands of dollars.

Leave a Comment