Astoria Mechanic | Collision Repair | Tolimas Auto Center

Overheated Engine

Why you should avoid overheating your engine

As temperatures rise and the summer driving season goes into full swing we will start to have customers towed in with overheated engines. In the hotter months your car’s engine cooling system has to work much harder to keep your engine from overheating and your air conditioner blowing cold. City driving is especially hard on your cooling system as main and auxiliary fans have to come on high in order to get enough air through your radiator as you sit in traffic. If you have your air conditioner running the radiator also absorbs heating from the ac condenser that gets extremely hot in order to deliver cold air into your automobile’s cabin. All this puts a tremendous strain on your engine’s cooling system which can be under 15 to 30 pounds of pressure and mostly made out of plastic.

Modern car engines are made out of aluminum which is a lighter metal than the older heavy iron engines they replaced. Aluminum engines are also easier to cast and machine which allows auto manufacturers to design engines that make more power. One unfortunate trade off is that aluminum engines are more sensitive to extreme temperatures. This causes them to be more prone to warping than older iron block engines. Engines warp around the sealing surfaces where the block and the head meet due to the extreme heat and pressure from the compression and combustion in each cylinder. On an aluminum engine a single overheat can cause the condition known as a blown head gasket. A blown head gasket occurs when the gasket between the head and block fails to seal and combustion gasses get into the coolant and the coolant leaks into the combustion chamber. This condition causes more overheating and is expensive to repair.

Head Gasket on Engine Block

Symptoms of a bad head gasket

The symptoms of a failed head gasket are misfires, randomly overheating engine, low power, and white smoke coming out of the exhaust. Head gasket[s] are expensive to repair as the job requires taking apart the top end of the engine. Then once the head[s] are removed having a machinist shave metal off the heads until they are perfectly flat and can seal again. Finally having a technician put everything back together again. This repair can exceed the value of most older cars.

Luxury and performance models from brands like BMW, Lexus, Land Rover, Mercedes Benz, Audi, Infinity, and Acura tend to be even more sensitive to overheating and repair. They tend to have bigger engines with two heads sealed to the block. Some engines also depend on turbo charging to make power, which adds turbo coolant lines to complicate the systems even more. All this adds to the price of repair if the engine were to overheat.

Other issues from overheating your engine

Auto manufacturers have also moved toward more plastic components and this includes parts in the cooling system. Radiators and coolant inlet pipes were once made out of metal, but now tend to be made out of specially molded plastic. As they age the plastics become brittle and start to leak. If a cooling fan were to fail and your engine were to overheat, all these plastic components will also have reduced service life. The plastic components would experience temperatures and pressures above their rating and will start to crack and leak.

How you can avoid overheating your engine

BMW Engine temperature warning

All these problems can be avoided by maintaining your coolant system and simply paying attention to your engine temperature gauge. If you ever see the reading moving up, towards the red markings or your dashboard outright tells you your engine is overheating then find a safe spot to pull over. As inconvenient as getting towed to a mechanic shop can be, it is more inconvenient to have to have to pay to get your engine repaired or find a new car because the repair costs more than what the car is worth. If your car is showing any of these symptoms and have further questions feel free to contact us at Tolima’s Auto Center.

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