Modern combustion engines generate a lot of heat during routine operation. The external temperatures around the engine can reach higher than 900 degrees Fahrenheit, which is too hot for some engine components if the heat doesn’t get managed correctly. Most of that heat gets released by the vehicle’s exhaust manifold, which is the metal pipe where the exhaust gas leaves the engine. To prevent such extreme heat from damaging your car’s under-hood components, a heat shield is installed to help contain and manage the higher temperatures.
Many times, the heat shield uses up to two layers of stamped metal, shaped into a U-shaped shield that wraps around your exhaust manifold. The shield is a heat sink and barrier, which prevents manifold heat from reaching the components under your hood to avoid damage. Most of the time, the heat shield lasts the lifespan of the vehicle or, more correctly, it lasts the lifespan of the engine. However, the shield can have issues and require service. It is essential to know what the symptoms are that your heat shield is failing or bad so that you can get to a trusted mechanic and take care of the issue.
Too Much Heat
Even if you’re not familiar with cars, you likely know how warm the engine gets after you’ve driven it to town and back. Therefore, you can usually tell if there is too much heat coming off the car because you feel it sooner. For example, if you can usually put your hand on the hood and now you can’t touch it without burning yourself, the engine bay is getting too hot, which signals that the heat shield is missing from the vehicle. You may also feel the heat emanating from the engine and hood of the car sooner. For example, you may get out of the driver’s seat and feel the need to give a wider berth to the front of the car when walking by it.
If your heat shield is bad or failing, you may experience a burning smell coming from your engine bay. The heat shield protects the bay from exhaust heat; if it starts failing to do that, the heat can reach plastics and the fluids within the vehicle. Other sensitive components are also at risk of burning up or overheating. You’re going to have a burning smell and might even see smoke. It is essential that you go to a trusted mechanic as soon as possible and stop driving the vehicle until the heat shield is fixed. Otherwise, you can severely damage the components under your hood, which cost more to replace.
While burning smells and excessive heat are both indications of a failing heat shield, neither of those options really produce noise. You may hear rattling noises coming from your engine bay if the heat shield is failing. The heat shield can become loose, broken, or damaged because of rust issues, loose hardware, or the fact that you drove over excessive bumps. The rattling sound is likely to be more prominent when you’re driving slowly and could change in tone or pitch depending on your engine speed.
If you’re lucky, the heat shield hasn’t pulled completely away or gotten too damaged to be put on again. Your mechanic may use a few washers and the original screws to cover up the large holes made when the heat shield tore free. This is a quick and inexpensive fix. However, it is best to let a professional mechanic handle this because they can also look for indications that the underside components are damaged or failing, as well.