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▷▷ 2021 ▷ What causes sludge in radiators?

6 julio, 2021

What Causes Sludge On Radiators?

by Shawn Lehrke

andresrimaging / iStock / Getty Images

Mud. It’s that thick brown substance you see when you open the radiator cap on your car. You usually notice it more after the engine has overheated. Unfortunately, the engine is likely to overheat due to a build-up of sludge. Since one of the main causes of breakdown on the road is the failure of the cooling system, pay special attention to the condition of your radiator.


Corrosion is the most common cause of sludge build-up on a radiator. The radiators are made of metal. Over time, the antifreeze breaks down. As it loses its protective qualities, PH levels change and corrosion sets in. Once this begins, rust, sludge, and scale builds up all over the cooling system, including the engine. The sludge can block the flow of coolant, causing the engine to overheat and leak. If left untreated, overheating and leaks can lead to very costly repairs.

Intake manifold gasket

When the intake manifold gasket is leaking, oil can enter the cooling system and cause sediment in the coolant. In this case, the cooling system is not the culprit, but if it is not discharged properly when the intake manifold gasket is repaired, the oily sludge that remains can cause costly damage to the cooling system.


Some General Motors vehicles require a coolant called Dex-Cool. This coolant is meant to last longer than regular antifreeze, and only needs to be changed every five years instead of two. Unfortunately, this new technology is believed to be the cause of headaches for some owners of these cars. According to complaints received by Consumer Affairs, Dex-Cool reacts with the plastic sealing surfaces, causing a leak in the intake manifold. The residue left by the breakdown is very sticky and thick like mud. Only a chemical wash will remove the sludge.

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