A car radiator may look good on the outside, but on the inside, it can have big problems. When a radiator becomes clogged, the entire cooling system is compromised, and serious mechanical damage can occur to your vehicle over time. Knowing how to diagnose a clogged radiator will not only save you a lot of money on repairs, it can also save the life of your vehicle.

Start the vehicle and let it run. As it warms up, touch the outside of the radiator with your hands to feel it. The entire radiator must be heated, since the hot coolant passes inside, if you feel hotter or colder places on the fins, the fluid is not circulating correctly, and that means that the coldest areas are obstructed.

With a cold engine remove the radiator cap and start the engine. Take the upper radiator hose and press it down to see how it feels when it has no pressure. Put the radiator cap on and rev the engine up to 3000 RPM (this does not have to be exact, what you want is to rev the engine a bit), then press the radiator hose again. A clogged radiator will send all of the fluid straight into the hose and make the hose stiff.

Replace the thermostat and hoses with new parts, if the vehicle keeps overheating with all other things working properly, then the radiator is clogged.

With a cold engine, remove the radiator cap. Aim the flashlight inside the radiator and look inside it. If the liquid looks like muddy water or smells like rubber, or if the fins are corroded with white sediment, then your radiator is not working 100% and is clogged.

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Warnings

Never open the radiator cap if the engine is hot. This can cause a serious accident, as the pressure of the fluid inside the radiator can transform the radiator cap into a projectile. What happens when the radiator breaks?

An automobile radiator is a metal device used to cool hot coolant in the engine. Radiators are made to cool the engine, but they can be damaged and broken for a number of reasons.

Causes

The main reason a radiator fails is internal corrosion. Copper and aluminum radiators are resistant to corrosion, but it can still occur. Radiators can also break from excessive heat and the impact of collisions.

Location

Radiators are more likely to break near the inlet and outlet hoses, as well as at the edges when the center is joined at the ends. These areas are more prone to buckling from normal car vibrations and movements. Breaks can be difficult to find, but refrigerant and vapor leakage can make it easier to determine when the system is hot and under pressure.

Effects edit

A broken radiator will allow coolant to escape from the cooling system, resulting in an inappropriate amount of coolant in the engine, which can cause damage from overheating. A low coolant level can cause the water pump to be improperly lubricated, which can also cause failure.

How to diagnose a cooling system problem?

There are a number of things that can go wrong with a car’s cooling system, causing the engine to overheat. The following is a list of things that you can easily check on your own; also, it never hurts to expand your knowledge about cars.

You should understand that overheating problems can be caused by a low coolant level, a plugged-in radiator, a stuck thermostat, or other common cooling system problems.

Check the coolant level in the reserve tank to see if you are low on coolant. Add coolant if necessary.

Open the radiator cap and look inside when the engine is cold.

Fill the radiator with a 50/50 mixture of antifreeze and water, if it is low or empty, and close the lid.

Check the upper and lower radiator hoses, located at the top and bottom of the radiator at the rear and held by clamps. Make sure the hoses are tightly attached and don’t leak.

Touch both hoses when the engine is slightly warm and the car is off. They should both be a little warm. If any are cold, you could have a stuck thermostat.

Use the palm of your hand to feel from the outside of the radiator from top to bottom, when the engine is slightly warm and the car is off. It should be hot to the touch evenly throughout the radiator. If there is a cold section, you could have an interior blockage in the radiator.

Check under your car, inspect the radiator, and look around the engine compartment for signs of coolant dripping. It is generally green, slimy, and sweet-smelling.

If there is a pool of coolant under your car it could be due to a water pump failure or a broken coolant reservoir.

Visit your mechanic if you know you have a leak but can’t find it. A mechanic can detect a small loss of coolant by pressurizing the cooling system.

Tips

A loose fan belt or a fan that is not running can cause overheating, even if there is enough coolant. A loose water pump belt or a broken water pump can also cause overheating, even though there is enough coolant. You can add coolant and water to the plastic coolant container when the engine is hot, but not to the radiator (except on German or Swedish cars, see Warnings). The coolant is a 50/50 mixture of water and antifreeze. It’s best to keep this ratio when adding to the coolant tank or radiator. Cars made before 1970 do not have a plastic coolant tank, you must wait for the engine to cool before adding fluid. Some older models have an added bag.

Coolant can drip into the car, usually on the passenger floor, if there is a central heating leak. When the central heating is turned off, the windshield will temporarily fog up from within.

Warnings

Never drive your car when the temperature gauge needle on the dash is in the red area; stop and turn off the engine before you damage it. Don’t open the radiator cap on a car with a hot or overheated engine, the coolant is under pressure and could scald you. German and Swedish cars have a plastic coolant reserve tank that is also pressurized, do not open it when the engine is hot. Refrigerant can injure or kill animals if ingested. Animals are attracted to the sweet taste of coolant, so clean up debris and don’t leave open coolant containers near animals.

Keep in mind that here at JB Euro Service we take pride in providing the best services for European cars in our area.