Why is My Car Overheating?

Overheated CarYour car may be overheating for a variety of reasons.  In this article we will look at some possible causes of a car overheating and a possible fix, whether easy or hard, for that particular situation.  As usual before we dive into the diagnostics let’s look at why a car gets hot.

It may seem pretty obvious to you that a car’s engine gets hot because of the explosions going on inside.  In the end this is the truth, the burning fuel/air mixture is what creates the heat in an engine.  Much of that heat gets pushed out with the exhaust gases but some of the heat’s energy soaks into the cylinder walls and heads before it is pushed out of the exhaust valves.  The reality is, this heat is really what makes your engine move.  The heat from the explosion of fuel and air cause the gases in the combustion chamber to expand rapidly.  These expanding gases force the piston in your engine down which causes the connecting rod to push the crack shaft around which turns the flywheel and voila, you’re motor is running!  This is why some people will call the internal combustion engine a “heat” engine.  This also means that the more heat you can produce in a single explosion, the more the gases will expand, the harder the piston is pushed down and the more power your engine will make.  Some engines do not create that much excess heat so there is very little worry of them overheating.  For example, the engine in your lawn mower doesn’t have a radiator or coolant and yes it gets warm when you run it, but under normal operating conditions it will never overheat.

As internal combustion engine technology increased, combustion temperatures increased because higher combustion temperatures make an internal combustion engine more efficient and more powerful.  As temperatures increased, new methods of keeping the engine materials from melting or being damaged were needed.  First air cooled engines were fitted with fins to help dissipate heat, then the water cooled engine was designed.  Water can remove heat from a surface much more quickly than air because it is a better conductor of heat.  Water cooling for engines allowed greater combustion temperatures and much more power and efficiency from smaller motors.

The engine in your vehicle is most likely a water cooled engine unless you have a vehicle from before the 1940s, or a very old Volkswagen or Porsche.  The benefits of a water cooled system have already been explained and the only problem with it is that a malfunction can easily cause catastrophic damage to the engine.  This is why it is extremely important to keep a watchful eye on the temperature gauge in your car and fix any overheating problems immediately.

Possible Causes for a Car Overheating:

  1. Lean Mixture of Advanced ignition timing:  Modern cars are fitting with electronic fuel injection and spark control so this isn’t a concern on modern cars, but we thought we would mention this for our classic car enthusiasts.  The result is the same if you do not have enough fuel mixed with your intake air charge, or if the spark fires too early.  As a mist of fuel is injected into the combustion chamber it can actually help cool the intake air charge.  If too little fuel is injected the air charge is not cooled enough and the mixture can begin to explode too early.  Similarly with more advanced timing, or too soon of a spark, the fuel/air mixture detonates too soon.  This means much more of the heat from the explosion is transferred to the cylinder walls and combustion chamber rather than expelled with the exhaust gases causing your engine to overheat.  Consider adjusting your carburetor to run richer, decreasing your initial timing advance, or changing your distributor weights and springs for less advance.
  1. Dirty Cooling System:  As you drive your vehicle, the cooling system can become dirty or clogged from wear particles, corrosion products or other impurities in your coolant.  Overtime and from the heat of normal operation these particles can cause scale to form on the inside of your engine or the radiator reducing heat transfer and making your cooling system insufficient for the needs of your engine.  In this case, consider using BlueDevil Radiator Flush to clean your cooling system and return it to its normal heat transfer capacity.  Get more information about BlueDevil Radiator Flush here.
  2. Low Coolant:  The cooling system in your vehicle is designed to operate with a full charge of coolant.  If you cooling system is low, there may not be enough coolant in your system to properly cool the engine.  For example, if the radiator is half empty, the coolant only has half of the time it is supposed to have in the radiator so it will enter back into your engine at a higher temperature so it will not be able to cool your engine properly.  Ensure you have proper coolant levels by checking the level in your overflow tank.  If you have low coolant, consider adding BlueDevil Pour-N-Go to your radiator before topping it off with the manufactures recommended coolant.  BlueDevil Pour-N-Go will seal any leaks you have in your cooling system insuring a proper coolant level and no more leaks.  Get more information about BlueDevil Pour-N-Go, click here.BlueDevil Pour-N-Go Head Gasket Sealer

    Pick up any BlueDevil Product at our partnering local auto parts retailers:

    • Bennett Auto Supply
    • Pep Boys
    • Car Quest Auto Parts
    • Prime Automotive Warehouse
    • Advance Auto Parts
    • O’Reilly Auto Parts
    • AutoZone
    • NAPA

    Picture courtesy of: northgeelongradiators.com.au

17 responses to “Why is My Car Overheating?

  1. Hey to whom this May concern I have added the blue devil in and it’s been working however today my car was over heating could you give me some suggestion on why my car is over heating?

    1. Victor-

      Defective fan switch, defective fan clutch, clogged or restricted cores, sediment deposits, systems jellied from antifreeze , or a faulty water pump could all be possible causes to lead to the vehicle overheating. You may want to have the vehicle further diagnosed so that you can pinpoint the problem.

  2. I had two cracked heads on a ’96 Dodge 1500 5.9 V8. I used Blue Devil in an attempt to ‘fix’ the problem. It seemed to help but it didn’t fix the overheating problem. I’ve since replaced the heads and a few other things to no avail. Could the Blue Devil have coated the inside of the block to the point that it is preventing the transfer of heat to the water?

    1. Harold-

      The BlueDevil Head Gasket Sealer will not coat the inside of the block nor effect the transfer of heat to the water. There are a number of different reasons that can cause an engine to overheat; they are not always related to the head gasket.

      We recommend that you have a certified mechanic diagnose the vehicle so that you can better pinpoint the cause of the overheat.

      Please contact us at 888-863-0426 in regards to the BlueDevil that was already used.

      Thanks,

      -BDP

  3. hi.
    i was driving my car, parked then turned off my igniyion. there was a grumbling noise and.then poof slight cloud a smoke. it was overheated. i took it to my mechanic and he said it melted something and i had to pay 600$ to het the ebtire cooling system fuxed, fans wires ect.. since then i drove my car about 2 days after on my way to work it was overheating even with my heat on i kept pulling over witch seemed to work but then i went up a small hill and.again it was overheating and again the grumbling noise but this time it was a huge thick cloud of smoke. i sat for 20min the car seemed fine started easy and i went home. a few days went by and today i was driving.and it was fine then i sat idle for about 3 min and it started to overheat again. im sumwhat pissed off because i spent 600$ thinkin they fixed it but yet my car is still overheating.and.i dont.understand why. if it was a gasket, wouldnt they have been.abke to spot.it being they did.a check over before they performed.the work?? help me please.

    1. Sarah,

      Thanks for your question about your car overheating. Without knowing what your mechanic replaced, it is difficult to tell where you problem is coming from. It could be something as severe as a blown head gasket or something as simple as installing a new thermostat. At this point, it sounds like your best course of action would be to go back to the mechanic and see if they will repair your problem under warranty because they didn’t fix the problem the first time.

  4. Hi there, I have a 2000 taurus V6 3.0 that overheat, the fans are perfect, oil is ok with no mixing oil with cooling system, no leaks and we just replace the thermostat.

    My mechanics sait is the head gaskets because the pressure go high and start overheating, I purchase the blue devil white container were no need to do anything but pour on cold temperature. Is this goin to work or should do the $600 fix.

    1. Rafael-

      Yes, we do recommend using the BlueDevil Head Gasket Sealer to help repair your Taurus.

      Based on your description, it sounds like your vehicle may be getting combustion/exhaust gases blowing into the cooling system and creating pressure. To give yourself the best overall chance of BlueDevil working successfully, in addition to the directions, you should remove the spark plug from the cylinder with the leak; this will be the spark plug from the cylinder with a low compression reading. If you are not sure which one that is, you may pull all of the spark plugs and will sometimes notice one will have a white-crystal-like substance on it and/or may look dirty; this is the plug you should pull. Leave that plug out for the 50 minute idle in order to relieve the pressure from building up and thus allowing the product to seal properly.

      Feel free to contact us with any questions.

      Thank you!

      -BDP

  5. My 2007 Jeep Grand Cherokee recently began overheating, but only when the car is idling after it has been running for a long time. I have been told that I have air leaking in to my cooling system at the #5 cylinder and that I need to have the head gasket replaced. Estimated Cost $1685. Can I use the Blue Devil pour and go?

    1. Chip-

      Yes, you can use the BlueDevil Pour-N-Go if the Jeep has a 6-cylinder engine. If it is a V8, we recommend using the BlueDevil Head Gasket Sealer (32 oz yellow label).

      Based on your description, it sounds like your vehicle may be getting combustion/exhaust gases blowing into the cooling system and creating pressure. To give yourself the best overall chance of BlueDevil working successfully, in addition to the directions, you should remove the spark plug from the cylinder with the leak; this will be the spark plug from the cylinder with a low compression reading. If you are not sure which one that is, you may pull all of the spark plugs and will sometimes notice one will have a white-crystal-like substance on it and/or may look dirty; this is the plug you should pull. Leave that plug out for the 50 minute idle in order to relieve the pressure from building up and thus allowing the product to seal properly. Feel free to contact our technical support line 888-863-0426 with any other questions.

      Thank you!

      -BDP

  6. Water is mixing with my oil I was told i have a cracked head i also see white smoke and it shuts off when I switch it in gear do you recommend your product??

  7. hi I have a 2005 Chevy equinox just had plug and wires put but been had to put antifreeze in it like every other day. put thermstace on water pump just put a heatcore on it ran hot today now he say it my 6 cylinder intake now I need a motor what should I do

  8. I have a 95 ford mustang srs V6 3.8L engine. On a long drive home with no cell phone and my 8 year old daughter in the car, with only miles of acreage of cows and oil fields my car puffed a nice little white plume of smoke from the exhaust and suddenly began to overheat. I had no other choice but to carefully continue our drive. After a while it started making a lovely sound, but we never red lined, it didn’t continually smoke, until we hit a hill and just couldn’t move anymore. Thick white smoke filled our area, and was pouring from the hood. My husband replaced the belt which had thrown, got it home the rest of the way, then replaced upper and lower radiator hoses, and the radiator. There is no more lovely sound that I can detect, and the smoke has dwindled, but she is still overheating. Could it be the waterpump, or am I in serious problems with a blown head gasket?

    1. Charlotte-

      Thank you for asking about your Ford Mustang. White smoke coming from the exhaust pipe is a tell-tale sign of a blown head gasket. If the water pump was faulty, it’s possible that you weren’t getting proper circulation in the cooing system, causing the vehicle to overheat and the head gasket to blow. You may want to check your service records to see when the water pump was last replaced, as it may be time for a water pump replacement. Also, you may want to check if your coolant is at the proper level, as the dwindling in smoke may just be from having low coolant. Once you have done that, you would be a good candidate for the BlueDevil Head Gasket Sealer. Feel free to contact our technical support team at 888-863-0426 with any other questions.

      Thank you!

      -BDP

  9. I don’t know if you can help me but I have a motorcycle issue my motorcycle which is a 1997 GSXR keeps overheating I’m told that newer ones because they’re fuel injected have a less chance of overheating I was also told that because the bike has 33000 miles on it that may be the radiator is clogged and needs to be flushed and that I should remove the thermostat and then put in a manual switch for the fan so that I could turn it on when I see it overheating do you think these are good ideas

    1. David,

      Thanks for your question about your GSXR. Your bike could be overheating due to running lean so you may consider having your carbs cleaned or rebuilt. Usually, carburated bikes run a little rich for safety, but if they are clogged it could cause a lean condition and an overheat. You do have a lot of miles for a sport bike so it is probably not a bad idea to flush the radiator and add new coolant. That is also a good time to replace the thermostat as they are inexpensive and the cooling system is already empty. We would recommend trying all those things before putting the fan on a switch. If you do decide to add a manual switch to your cooling fan, make sure you wire it in such a way that it still comes on automatically when the bike gets too warm.

      Thanks again for your question!
      -BD Auto Pro

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