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Lou’s Garage

My van is overheating and the engine knocks, what can I do? Add to ...

My 2004 Kia Sedona recently had a leak in the radiator hose, which led to the van overheating. However, now the water in the radiator reservoir is full of what appears to be rust and my engine knocks hard when trying to start; it is getting tougher every time I try. Any idea what the knock is? Also, when the car overheated, it showed no oil in the car. So we added two quarts. Now, the dipstick is showing 3-4 inches over the full line. – Zachary A.

You have a lot happening here, but I suspect it’s all going to net the same result. I will assume that the overheating of the engine caused one or both of the cylinder heads to warp, leading to head gasket failure.

When a head gasket fails, it can no longer effectively seal the engine, and antifreeze will start leaking into the combustion chamber – quickly contaminating the engine oil.

It may appear your dipstick is overfilled with oil, but I suspect that the “3-4 inches over the full line” is actually a mixture of oil and antifreeze.

Antifreeze makes for a poor lubricant so, as you ran the vehicle with this soupy mixture, the vital engine components were not being adequately lubricated – which is likely why your engine is knocking. It’s time to start looking for a used engine, as resuscitating the existing engine is probably going to exceed the value of the vehicle.

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