Though an overheated engine is something commonly associated with the dog days of summer, the most likely root cause of your hot engine is something that can affect your vehicle anytime of year. Let’s take a quick look at what could be going on, how to avoid permanently damaging your engine, and how to stave off the threat going forward.
Common Culprits
Coolant Leaks
This is the most common cause, as a small leak can be easy to miss, and if you aren’t keeping tabs on your fluid levels you may find out your dangerously low on coolant the hard way. The most likely spots to check are radiator hoses, the radiator itself, and around the water pump. Another possibility could be a head gasket, which leads to your motor oil and coolant mixing internally; an easy check is to look at your oil dipstick and/or at your coolant by removing the radiator cap (after it’s cooled), and should either look like a chocolate milkshake you’ve, unfortunately, found the leak.
Low Coolant Level
Though this may seem repetitive from above, you don’t have to have a leak to end up with low coolant. Unsurprisingly, coolant evaporation takes much longer than losing it through a leak, but it’s still important to keep an eye on your levels to keep it topped off.
Faulty Thermostat
The thermostat simply controls the amount of coolant that flows through the engine block. Most often the failure here is simply the thermostat getting stuck closed, and depending upon the age of your vehicle, this can be due to a mechanical issue, though modern cars have a secondary concern in regards to the electronic control unit, as the ECU controls the thermostat.
Water Pump Failure
Not unlike the thermostat, the water pump does what the name implies, and when it stops so too does the flow of coolant throughout the engine. If you’re lucky the water pump will give you a warning before completely failing with “whining” bearings, giving you the chance to replace it.
Radiator Issues
Beyond obvious leaks, radiators can clog internally and even receive damage to external fins that restrict not just coolant but airflow. Since this is where the coolant dissipates heat before returning to the furnace of your motor, less airflow leads to higher tramps, pressure, and ultimately the recognizable image of steam rolling from underneath the hood.
Broken Radiator Fan
As just discussed, air passing through your radiator is important, and your radiator fan is what keeps coolant cool while you're driving at low speeds or stuck in stop and go traffic. If it’s not engaging then it doesn’t take long to get an angry heat gauge in normal city driving, not to mention rush hour traffic.
Head Gasket Failure
We saved this for last, as, of this list, it’s likely the last one you’ll want to deal with. As mentioned under “Coolant Leaks”, the head gasket keeps your engine’s cylinders (where the oil is) separate from the water jacket (where the coolant flows) inside your engine block. If this barrier degrades to the point of allowing the two to mix it can lead to catastrophic results for your motor, though it can be saved when caught and addressed early. This, unfortunately, still requires partial engine disassembly to replace said gasket.
The Dangers of Overheating
While we’re here, let’s quickly go through the reasons to not push an overheated engine:
Head Gasket Failure
Though we’ve just covered this as a potential failure point, if the head gasket isn’t the root cause, continually driving a hot engine can affect the head gasket regardless. Since the heat starts with the engine block, it can expand at a different rate than the cylinder head bolted into it, meaning added stress on the gasket sandwiched between the two.
Warped Cylinder Heads
And since we’re talking about cylinder heads, excessive heat can cause them to warp, which is notably worse than the head gasket replacement we’re already looking to avoid.
Piston Damage
If we’re cascading into overworking our already hot engine, then pistons, the things made for handling the minor explosions that make our car go, also have a breaking point, and this heat can cause cracks or a complete seizure.
Engine Seizure
This can be anything from internal parts warping and breaking to essentially fusing together from the immense heat. It’s at this point especially you’ll be looking for a complete replacement.
Preventing Overheating Through Basic Maintenance
We don’t need to be all doom and gloom here, let’s look at how to keep our cooling systems happy and healthy throughout their life.
Regular Coolant Flushes
Your owner’s manual will have details regarding your vehicle’s recommended intervals for flushing and replacing coolant. It works hard and has an effective lifespan, so you’ll want to make sure not to get caught thinking that topping it off is all that’s required.
Check Coolant Levels Regularly
It’s good to get in the habit of checking all your fluid levels regularly, at least once a month, to ensure everything’s running as it should. Doing so can also give you a heads up if something’s going wrong before a dash light or noise tips you off.
Inspect Hoses and Belts
Since you’re already under the hood, give those hoses and belts a look too. Cracks in belts and bloated hoses are your warning that they’re losing their integrity, so you can get them replaced before they have a chance to cause you trouble.
Check Radiator and Fan
You don’t have to be an off-roader or live on a gravel road to pick up debris in your radiator and fan area, so just give it a peek and make sure it’s free and clear.
Stay Cool
If you found this article because you’re experiencing overheating and would like some further help, we invite you to schedule an appointment with our techs to get you and your vehicle safely back out on the road. Take care out there!