Symptoms of a Bad or Failing Coolant Reservoir

coolant reservoir

The coolant reservoir is the plastic reservoir mounted in the engine bay that stores the coolant for the engine. Coolant reservoirs are required because engines go through cycles of expelling and absorbing coolant as they warm up and cool down. When the engine is cold, the pressure of the cooling system is low and more coolant is required, and when the engine is warm the pressure of the cooling system is increased and therefore less coolant is required.

For some vehicles, the coolant reservoir is an integral part of the system, and since it is also pressurized, the coolant reservoir becomes an even more important component to engine safety. Because the coolant reservoir is part of the cooling system, when it has any issues it can quickly lead to issues with the engine. Usually a bad or failing coolant reservoir will produce a few symptoms that can alert the driver that a problem has occurred and should be serviced.

1. Constantly low on coolant

One of the first symptoms commonly associated with a bad or failing coolant reservoir is the need to constantly add coolant. If the reservoir cracks or develops any small leaks it can cause the coolant it is storing to leak or evaporate at a slow rate. The leaks may be small enough that they may not be obvious to the driver, however, over time they will cause the reservoir to empty out. The constant need to add coolant can also be caused by a leak somewhere else on the engine so a proper diagnosis is recommended.

2. Coolant leaks

Another symptom of a potential problem with the coolant reservoir is coolant leaks. If the coolant reservoir cracks or breaks due to old age or overheating it will leak. Small leaks may produce steam and drips, while larger leaks will produce streams and puddles, as well as an obvious coolant odor.

3. Engine overheating

Another more serious symptom of a bad or failing coolant reservoir is the engine overheating. If the coolant reservoir has any issue that prevents it from properly holding coolant, or from properly pressurizing the system it may cause the engine to overheat. Any issue that causes engine overheating should be addressed as soon as possible in order to prevent any possible damage to the engine.

The coolant reservoir is a simple but important component of the cooling system, and when it has issues it can quickly lead to overheating and even engine damage. For this reason, if you suspect that your coolant recovery reservoir may be having an issue, have the vehicle inspected by a professional technician, such as one from YourMechanic. They will be able to determine if the car needs a coolant reservoir replacement.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

More related articles

Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
Veteran and Military Driver Laws and Benefits in Idaho
The state of Idaho offers a number of benefits and perks for those Americans who have either served in an Armed Forces branch in the...

Related questions

Q: Coolant leak around water pump

Hi. This is a sign that the seals in the water pump are beginning the fail. Behind the pulley, there should be a small hole for the coolant to leak out of. Without the hole, coolant could seep into the...

Q: Car overheating

Start with checking the engine coolant level. If it is low, you have a leak. If the level is normal, the problem could be with the thermostat. If the thermostat isn't opening, coolant won't circulate. If it is opening, the...

Q: I went to auto zone to do diagnostic on my car because in the middle of traffic my car was overheating auto zone did the test and

The vehicle should not have been driven home with the engine overheating. It's possible that you may have now blown a head gasket and damaged the engine. The fan relay connection, if it is melted, would be due to the...