A climbing temperature gauge is alarming, indicating possible overheating issues. However, some engines can run hotter than normal without actually overheating.
Let’s consider some of the things that can cause higher-than-normal engine operating temperatures, without actual overheating (not all of them are serious), and we’ll tell you how to proceed the moment you notice your temp gauge rising.
Causes of a Car That’s Running Hot But Not Overheating
A vehicle’s engine can run hot, but not overheat, for a number of reasons. Knowing what those reasons might be can assist in solving the problem at hand. Here are some of the most common explanations for a rising engine temperature.
#1. Faulty Water Pump.
If your vehicle’s engine is running hotter than usual, but is not actually overheating, a faulty water pump might be at fault. An engine’s water pump circulates coolant between a vehicle’s radiator and the engine block itself.
However, damage to a water pump’s impeller may prevent this circulation from taking place effectively.
#2. Sticking Thermostat.
A partially stuck thermostat can prevent coolant from circulating normally, causing an engine to run hotter than it should. When stuck between a fully-opened and a fully-closed position, a thermostat is little more than a restriction in the cooling system.
In this state, heat is not being exchanged properly between the engine itself and a vehicle’s radiator. Fortunately, the cost to replace a thermostat is usually fairly low.
#3. Blockages In the Cooling System.
Just like our sticking thermostat example above, any restriction within the engine’s cooling system can lead to slightly higher than normal operating temperatures.
This condition occurs most often when a vehicle’s radiator has become clogged by rust or other sediment. A collapsed radiator hose would have the same effect.
#4. Inoperable Engine Fan.
It is the job of a vehicle’s cooling fans to move air across the face of the vehicle’s radiators. Also, of concern here might be a cooling fan that is not otherwise running properly, or even a fan relay that is shorted or open.
In these cases, replacement of the fan or repair of the fan’s control circuit is necessary to restore proper readings. Vehicles with mechanical cooling fans may also exhibit these same symptoms with a failing fan clutch.
#5. Blown Head Gasket.
A blown head gasket can also result in higher-than-normal running temperatures. This often occurs as a result of coolant loss, due to leakage from a cylinder into the cooling jacket.
However, a blown head gasket can also allow combustion gases into a vehicle’s cooling system, meaning a higher-than-expected operating temperature is registered.
#6. Low Coolant Levels.
In many cases, a slightly higher than normal temperature can result from little more than low coolant in a vehicle’s radiator.
This occurs when an engine’s cooling system has developed one or more leaks, however minor. When this is the case, there simply is not sufficient coolant left to properly cool the engine.
#7. Faulty Temperature Sensor or Gauge.
In some instances of higher-than-normal engine temperature readings, the vehicle in fact is not running hotter than normal at all.
A faulty temperature probe or other gauge may be what is subject to fault, leading you to believe a condition exists when nothing is really wrong.
What To Do If You Notice Your Temperature Gauge Rising?
If you see that your vehicle’s temperature gauge is rising, pull over and shut off your vehicle.
While there may not be anything wrong with your engine at the moment, any deviation from a normal temperature reading could indicate the potential for more temperature-related problems to come. Once your engine has cooled, you should make your way back home or to the nearest service center.
Always take every precaution regarding the fact that your engine’s operating temperature is not regulating itself as it should. If concerns of this type develop into a more serious problem, an eventual overheating can cause catastrophic damage to the engine.
An overheated engine can easily blow a head gasket, warp a cylinder head, or crack a block.
In any event, the underlying cause of the problem must be diagnosed and remedied at the first possible opportunity, lest a serious overheating and the damage that follows occur.
If you do not feel comfortable diagnosing the problem yourself, make an appointment with an independent mechanic or dealer service center at the earliest opportunity.
Do Some Vehicles Simply Run Hotter Than Others?
Some vehicles do run hotter than others naturally, though these differences are normally only slight. The reason some vehicles run hotter than others relates to the rated temperature of an engine’s thermostat.
This component controls the flow of an engine’s coolant between its block/cylinder heads and a vehicle’s radiator.
Thermostats are available in a range of preset temperatures, which indicate the point at which the thermostat itself will open, allowing flow and transfer of heat to take place. The higher a thermostat’s temperature rating, the hotter an engine will run.
Manufacturers choose a particular thermostat pertinent to the optimal temperature required for efficient combustion.
Temp Gauge Rises When: Going Uphill, Idling, or When A/C Is On
If your engine’s temperature only rises above normal in one or more of the above situations, a marginal cooling system is generally the problem.
The reason—as you might have guessed—is that an engine’s cooling system is never more severely tested than when a vehicle is climbing a steep hill, being driven with the air conditioning on, or idling for a long period.
When hotter than normal temperature readings are noticed with this type of operation, a lack of cooling system efficiency is usually to blame. Sometimes, a general lack of coolant is the problem, caused by one or many leaks in the cooling system. Sometimes, another look for blockages in the cooling system may well be indicated.
Another vicious little man behind the curtain of overheating during periods of maximum load is the cooling fan. And, without a working cooling fan, the engine has very little chance to regulate its operating temperatures as it otherwise might.