Checking coolant flow in your radiator is crucial for preventing overheating. Here's how to do it:
1. The Touch Test (with caution!):
- Engine warm-up: Start your engine and let it run until it reaches its normal operating temperature.
- Hose inspection: Carefully (the engine and components will be HOT!) feel the upper and lower radiator hoses.
- The upper radiator hose should be hot, around 190–200°F (88-93°C). This indicates hot coolant is exiting the engine and entering the radiator.
- The lower radiator hose should be noticeably cooler than the upper hose. This means the radiator is doing its job of dissipating heat.
Important Safety Note: Never open the radiator cap while the engine is hot. Pressurized hot coolant can spray out and cause severe burns.
Tools you can use
- Infrared Thermometer: An infrared thermometer provides a safer and more accurate way to check the temperature of the hoses without direct contact. Aim the thermometer at the upper and lower radiator hoses and record the readings.
2. Visual Inspection (Coolant Circulation):
- Radiator Cap (when engine is cold): When the engine is completely cool, carefully remove the radiator cap.
- Check for Circulation: Start the engine. You should be able to see coolant flowing inside the radiator. If there is no flow or very little flow, it could indicate a problem with the water pump, a blockage, or a thermostat issue.
3. Inspect the Coolant Reservoir:
- Check Coolant Level: Ensure the coolant level in the overflow reservoir is between the "min" and "max" lines.
- Look for Bubbles: With the engine running, check for bubbles in the coolant reservoir. Bubbles can indicate a head gasket leak, which introduces combustion gases into the cooling system.
4. Professional Check:
If you are unsure about any of these steps or suspect a serious problem, it's best to take your vehicle to a qualified mechanic for a professional inspection. They can perform pressure tests and other diagnostics to pinpoint the exact cause of any cooling system issues.
Here's a summary table of the checks:
| Check Method | Procedure | Indication of Good Flow | Possible Issues if Flow is Bad |
|---|---|---|---|
| Hose Temperature | Feel upper and lower radiator hoses (carefully when hot!). | Upper hose hot, lower hose cooler. | Blocked radiator, faulty thermostat, failing water pump. |
| Visual (Radiator) | Remove radiator cap (when cold!), start engine, observe coolant flow. | Visible coolant circulation within the radiator. | Water pump failure, blocked radiator core, air lock in the system. |
| Reservoir | Check coolant level, look for bubbles with engine running. | Coolant level between min/max, no bubbles. | Low coolant, head gasket leak (if bubbles are present). |
Checking coolant flow is an important part of regular vehicle maintenance. Addressing issues promptly can prevent costly engine damage.
