Symptoms of a Bad or Failing Heat Shield

Modern internal combustion engines generate a considerable amount of heat during their regular operation. External engine temperatures routinely reach upwards of nine hundred degrees fahrenheit, which is hot enough to be hazardous to engine components if the heat is not managed properly. A majority of that heat is released by the exhaust manifold, the metal pipe through which the exhaust gases exit the engine. In order to prevent this extreme heat from damaging the components under the hood, a heat shield is used to help manage and contain the high temperatures.

Most heat shields consist of one or more layers of stamped metal that are shaped into a shield that is designed to wrap around the exhaust manifold. The shield acts as a barrier and heat sink, preventing the heat from the manifold from reaching any of the components under the hood and potentially causing damage. While most heat shields will generally last the life of the vehicle, or at least the engine, they can sometimes encounter issues which require service. Usually a bad or failing heat shield will produce a few symptoms that can alert the driver of a potential issue.

1. Excessive heat from the engine bay

One of the first symptoms of an issue with the heat shield is excessive heat from the engine bay. If the heat shield fails to provide protection against the heat generated by the engine bay for any reason, such as it becoming damaged, or loose, that heat will soak into the engine bay. This will cause the engine bay to become hotter than normal. Depending on the intensity of the heat the vehicle will be warmer than normal near the vehicle’s front of the end, and even more so when the hood is opened. In some cases the hood may even become hot to the touch, from soaking up the excessive heat.

2. Burning smell

Another symptom of a bad or failing heat shield is a burning smell from the engine bay. If the heat shield fails to protect the engine bay from the exhaust heat it may eventually lead to a burning smell from the engine bay. If the heat reaches any plastic, or especially sensitive components it may cause them to overheat and burn up. This will produce a burning smell, and in some cases even smoke, aside from potentially damaging the affected component.

3. Rattling noises from the engine bay

Another, more audible, symptom of a bad or failing heat shield is rattling noises from the engine bay. If the heat shield becomes loose, damaged or broken, perhaps due to loose hardware or damage from rust, it will cause the heat shield to vibrate and produce a rattling sound. The rattling will be most prominent at low engine speeds, and may change in pitch or tone according to engine speed. A close inspection would be required to determine if the rattling noises are from a broken, or simply loose, heat shield.

While most heat shields will last the life of the vehicle that does not mean that they are not susceptible to failure. If you suspect that your heat shield may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic, to determine if the shield should be replaced.


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Ira

36 years of experience
259 reviews
Ira
36 years of experience
Ford Edge V6-3.5L - Exhaust System Inspection - Brandon, Florida
Ira was prompt and was able to diagnose the issue quickly even though it had been misdiagnosed by a chain repair shop.
Chevrolet Blazer - Exhaust System Inspection - Tampa, Florida
Ira was amazing and honest. I scheduled for the wrong service. He explained what I needed and took care of the car appropriately. Your mechanic is a fantastic service with wonderful people. If you have the option for Ira, do not hesitate!

Kyle

12 years of experience
137 reviews
Kyle
12 years of experience
Honda Accord L4-2.3L - Exhaust System Inspection - Jenkintown, Pennsylvania
Extremely helpful! He saved me money wherever he could, he was extremely patient and answered any question I had. I strongly recommend him.
Buick Century - Exhaust System Inspection - Philadelphia, Pennsylvania
Very perfessional and honest and those are rare traits for a mechanic. Dude save me money and a headache! I'm using him for any of my car needs or anyone I know!

Michael

4 years of experience
176 reviews
Michael
4 years of experience
Ford Escape V6-3.0L - Exhaust System Inspection - Carmel, Indiana
Michael was able to help diagnose my car's issues quickly, competently, and professionally. I trusted his advice and appreciated his expertise.

JOHNNY

33 years of experience
189 reviews
JOHNNY
33 years of experience
Ford F-350 Super Duty V8-6.7L Turbo Diesel - Exhaust System Inspection - Rocklin, California
Very knowledgeable and professional. Was able to explain in detail what he was looking for. clear that he knew the truck inside and out

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