The cooling system keeps your engine at the right temperature, and an overheated engine can be wrecked in minutes. A little regular care prevents most cooling failures. This guide explains how the system works and what to check.
How the cooling system works
The water pump moves coolant through the engine, where it absorbs heat. The hot coolant flows to the radiator, which releases the heat to the air, helped by the fan. The thermostat controls the temperature by opening and closing the flow, and the radiator cap keeps the system under pressure so the coolant boils at a higher temperature. The same coolant also feeds the heater core that warms the cabin.
What to check regularly
- Coolant level: check the overflow reservoir when the engine is cold. It should sit between the min and max marks.
- Coolant condition: it should be clean and the color your maker specifies. Rust-colored or oily coolant means a problem.
- Hoses: squeeze them when cold. They should be firm, not soft, cracked or bulging.
- Radiator and fins: look for leaks, damaged fins and debris blocking the airflow.
- Belts: a worn belt that drives the water pump can cause overheating.
- Leaks: puddles under the car, a sweet smell or crust around fittings.
Use the right coolant
Coolants differ in chemistry and color, and the right one depends on your vehicle. Use the type in your owner's manual, mix it with distilled water as directed (often a 50/50 mix) and do not mix different coolant types.
Signs of overheating
A rising temperature gauge, a warning light, steam from under the hood, a sweet smell and loss of heater output are all signs. If the engine overheats, pull over safely and switch it off. Never open the radiator cap on a hot engine: the system is under pressure and can spray scalding coolant.
When to flush or replace parts
Flush intervals vary widely by vehicle, from about 30,000 miles to over 100,000. Follow the manual. Replace a thermostat that sticks, a water pump that leaks or whines, and a radiator that is clogged or leaking. For towing, hot climates or modified engines, a higher-capacity aluminum radiator and electric fans add a margin of safety.
Common questions
Can I just add water when the level is low?
In an emergency, yes, but it dilutes the coolant and its protection. Top up with the correct coolant mix and find out why the level dropped.
Why is my heater blowing cold air?
Low coolant, trapped air or a clogged heater core are common causes. Check the level first.
Where to buy
Shop cooling parts, including Mishimoto radiators and fans. We are an authorized dealer for every brand we sell, shipping is free anywhere in the USA, and returns are accepted within 60 days (unused, in the original packaging) and return shipping is free. Not sure what fits your vehicle? Contact our support team and we will help you check before you order.