Cooling an engine is one of the most important systems on a vehicle. Without it, the engine will overheat and cause some serious issues, including seizing the engine so it has to be replaced. Overheating can cause cracking of the gasket or other issues which will end up costing thousands to fix, so why does coolant stop circulating?
There are many reasons for coolant to stop circulating. This can be because of a blockage in the radiator, hose issues, leaking, thermostat failing, low coolant, or the water pump having issues.
We’ll look at the common causes of coolant issues in vehicles as well as how to spot exactly what the issue is. I’ll also show you how to fix these issues yourself as well as signs that you need to go see a mechanic or get replacement parts. To stop the issue from recurring the car needs to be thoroughly checked and tested and the root cause addressed.
Can You Mix Different Coolant Brands?
What Causes Coolant Not To Circulate?
There are many components to a vehicle’s cooling system that work to circulate the coolant. If one or more of the components fail, then this can cause a series of other issues leading to overheating. Knowing the symptoms caused by each part can assist you in identifying why coolant doesn’t circulate.
Can a bad thermostat cause coolant not to circulate?
An issue with the engine’s thermostat is the most common cause of coolant circulation issues leading to overheating. The thermostat not operating properly will prevent the values from opening and closing. This will likely stop or hinder coolant flowing or circulating through the engine.
Another common cause is there is some sort of blockage in the radiator. These can be external or internal faults causing blockages.
External issues with radiators are generally the result of too much dirt or similar not allowing airflow around the radiator. This prevents the radiator from working properly and can cause issues with overheating. When the radiator stops working you risk destroying the engine irreparably. A simple vacuum or leaf blower can do wonders to clean a dirty radiator.
Internal blockages will prevent the coolant from circulating. Such blockages in the radiator can be remedied by draining all coolant and then flushing the radiator, as well as all connecting hoses, with water. If blockages cannot be removed using this method, it is unlikely the radiator can be fixed and it is best to purchase a new one.
Leaks of coolant will severely impact the ability of the radiator to cool itself let alone circulate the coolant. There are cooling system pressure testers you can get from an auto parts store to check for leaks. Coolant systems are pressurized and such tools use this fact to help test for leaks.
These cooling system pressure testers need to be calibrated to the pressure noted on the radiator cap and then are very useful in helping diagnose loss of pressure and thus potential leaks.
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Coolant dyes can also be used to try and find leaks. The first thing to look for is any green liquid found under a vehicle, especially if it has been parked somewhere for some time. Leaks will result in you losing coolant over time which then due to the suboptimal pressure in the engine will prevent the circulation of coolant.
It is also worth checking the pump for the coolant system. The pump may be faulty, or not being properly activated via the engine’s management system. If you remove the cooling system pressure cap and warm the engine up, you should see the coolant start to circulate.
As faults with the water pump may look like thermostat issues and vice versa, you should go through both systems thoroughly before replacing either.
The hoses carrying the coolant are prone to blockages or collapsing. Draining the cooling system and running water through the hoses can test for blockages. The hoses could be internally collapsed and so hard to see such blockages from the outside. If water cannot pass through the hoses they will need to be replaced.
Do You Add Coolant While The Car Is Running?
How To Know If Coolant Is Circulating?
One way to tell if the coolant is circulating is to look at the radiator filler neck. With the car off or just turned on, it should not be flowing as the thermostat has not been triggered by the car reaching the operating temperature yet. Once the vehicle has warmed up enough you should see coolant start to circulate.
One way you can tell if you’re having coolant issues is if your vehicle is overheating. If your vehicle constantly overheats, this is one of the most common signs that your radiator is bad or failing possibly due to coolant issues.
If your temperature gauge is warning you or reading very high you should immediately turn off the engine and check if it is a sign of a more serious issue. If the temperature gauge is reading high into the red, particularly soon after turning it on, this should be looked into immediately.
How To Make Coolant Circulate?
To make coolant circulate, you will have to work out what if any of the other components are failing. Once you have found out the source of the issue, fixing it should see the coolant circulate again. Until you can get the coolant circulating and the radiator working, it could be causing serious damage to your engine if you continue to run it.
Draining and flushing out old coolant as well as accumulated sediment is a good first step. Make sure in particular that the coolant you use is rated for your vehicle as well as containing antifreeze.
Otherwise, the vehicles’ systems should keep coolant circulating to stop overheating. Even temporary issues with coolant can be a sign of major issues with the vehicle and should be taken seriously as soon as you become aware of them.
