Can a Bad Thermostat Cause Engine Misfire?

The engine thermostat plays an important role in heavy equipment such as excavators and loaders. It regulates the flow of coolant and keeps the engine running at an optimal temperature. However, many equipment operators face questions like: Can a faulty thermostat cause an engine misfire? Can a diesel engine run without a thermostat? Will a faulty thermostat cause the check engine light to illuminate? How much does it cost to replace a thermostat? In this article, MyMROmarts will answer these questions for you.

 

Can a Bad Thermostat Cause Engine Misfire?

In short, a thermostat failure can indeed cause an engine misfire. The reason is that a malfunctioning thermostat directly affects the engine's operating temperature, which in turn interferes with the combustion process of fuel and air.

1. Overheating problem

When the thermostat is stuck in the closed position, the coolant cannot flow. The engine temperature rises rapidly. This overheating condition causes incomplete combustion of the fuel in the combustion chamber, causing the engine to misfire.

2. Overcooling problem

When the thermostat is stuck in the open position, the coolant will continue to circulate. The engine will also not be able to reach normal operating temperature. In this case, the fuel atomization effect is poor, which can also easily lead to misfires.

 

Can You Run a Diesel Engine Without a Thermostat?

In theory, a diesel engine can run without an engine thermostat. But we don't recommend it.

1. The engine can't heat up quickly

Without a thermostat, the coolant will flow directly. The engine takes longer to reach operating temperature. This will increase fuel consumption and accelerate the wear of parts.

2. Reduced operating efficiency

Diesel engines need a high temperature environment to achieve optimal combustion efficiency. When the operating temperature is too low, the engine performance will drop significantly.

3. Long-term damage to the equipment

Running without a thermostat for a long time will put the cooling system and the internal parts of the engine at greater risk of wear. Therefore, even if the thermostat fails, it should be replaced as soon as possible instead of simply removed.

 

Can a Bad Thermostat Cause a Check Engine Light?

Yes, a thermostat failure usually triggers the engine check light to come on.

In modern excavators and loaders, the engine's operating status is monitored in real time by the electronic control unit. When the thermostat fails, the check light may be triggered in the following two situations:

1. Temperature sensor abnormality

When the ECU detects that the engine temperature is too high or too low, it will record the fault code and light up the check light.

2. Reduced combustion efficiency

The combustion problem caused by the thermostat failure will cause excessive emissions, which will trigger the check light.

When the check light comes on, it is recommended to use a diagnostic tool to read the fault code immediately. Further, confirm whether it is related to the thermostat and take repair measures in time.

 

How Much Does It Cost to Replace an Engine Thermostat?

The cost of replacing an engine thermostat varies depending on the model of equipment and the complexity of the repair.

 

Regular thermostats typically cost between $40-100, while high-performance thermostats for heavy equipment can cost as much as $150-300. MyMROmarts offers a wide range of diesel engine thermostats for brands such as Cummins, Bobcat, CAT, Hitachi, John Deere, Komatsu, and Kubota, ranging from $9-120, reliable and affordable.

 

The thermostat is a crucial component of heavy machinery like loaders and excavators, despite its tiny size. The thermostat must be maintained in order to prevent engine misfires, guarantee the diesel engine runs normally, or stop the engine check light from turning on. As soon as a thermostat issue is discovered, it is advisable to identify and fix it.