Coolant Loss, Overheating and Other Cooling System Issues

While it is natural for your vehicle to lose some coolant in the summertime, you shouldn’t experience a significant drop in coolant level at any time of year. It’s also understandable for your engine to run a little bit hotter at consistently higher speeds or with the air conditioner blasting at the highest setting.

However, it’s never good for your vehicle’s temperature gauge to reach the red zone, or for steam to begin to appear from under your hood. If either of these things occurs, then a breakdown and severe engine damage are likely to occur.

Why Does Your Vehicle Lose Coolant in Hot Weather?

Engine coolant is stored in the radiator in the front of the vehicle and circulates between the radiator and the engine to cool the engine as needed. The heat from the engine transfers to the coolant, which expands in volume as all liquids do when heated.

This expanding effect would create great pressure in the radiator and the hoses where the coolant travels, if not for the addition of a recovery tank between the engine and the radiator. This tank contains the overflow created by the expanded coolant.

When the recovery tank becomes too full, it spills additional coolant onto the ground. This is especially noticeable during the summer because your coolant must deal with the summer heat and the stresses of heavy air conditioner use.

As the coolant cools, it returns to its regular volume – minus the coolant that may have been expelled through the overflow tube of the recovery tank. Repeated episodes of coolant overflows can result in coolant loss. You can check your coolant level by examining the high- and low-level markings on the side of the recovery tank.

You should be able to observe the coolant level through the clear plastic surface of the recovery tank. If the level is below the “Low” line, add coolant until it reaches a point between the “Low” and “Full” lines. While it won’t hurt your vehicle to fill the tank to the top, the excess coolant will just spill out of the tank when it becomes heated.

You must only add the type of coolant that is suggested by the manufacturer of your vehicle. Using substandard coolants or water to fill the tank may cause overheating to occur.

What Are Other Causes of Coolant Loss?
While overflow of coolant from the recovery tank is normal, losses from other causes are signs that repairs are needed. You may have a hole in your radiator that may have corroded over time.
If you notice puddles of coolant under the front of your vehicle, rather than to the side of the engine compartment where the recovery tank releases coolant, then it’s likely that you need a hole patched or a new radiator.

Look for pinholes, bubbles, cracks or wet spots, particularly around hose clamps, on both the top and bottom radiator hoses. Defective hoses are ticking time bombs – ready to burst under pressure in the most inconvenient places, such as on a highway in the middle of summer traffic.

What Are Some Possible Causes of Overheating?
If your temperature gauge rises suddenly to the red zone at the top of the gauge, you must turn off the vehicle as soon as possible to minimize the chance of engine damage. However, your vehicle may just be running hotter than normal – above the midway point between cold and hot. Possible causes include:

  • Degraded coolant
  • Failing thermostat
  • Loose fan belt or failing radiator fan
  • Water pump failure

Whatever the cause, engine overheating is bad for the engine as well as the occupants of your vehicle in the event of a breakdown. You’ll want to take your vehicle into an auto repair shop as soon as possible.
If your car is overheating, then contact the service professionals at Neuhaus Service, Inc. You’ll receive quality work at a fair price, along with honesty and integrity at no additional charge.


3241 Kerner Blvd, #10A
San Rafael, CA 94901