Antifreeze In Oil Pan: Causes And Solutions

Antifreeze in the oil pan is a serious issue that can cause severe engine damage. It occurs when there is a failure in one or more of the engine's gaskets or seals, allowing coolant and oil to mix. This can be due to a blown head gasket, a cracked cylinder head, or a damaged engine block. A sweet smell, coolant loss without any visible leaks, and a milky colour in the crankcase are all indicators of antifreeze in the oil pan. To fix this issue, it is recommended to seek professional help or, if the problem is caught early, drain the coolant and replace it with engine oil.

Cracked cylinder head or blown head gasket

A cracked cylinder head or a blown head gasket can cause coolant to mix with the engine oil. This happens when a crack in the engine block is deep enough to allow the passage of antifreeze into the engine oil passageways.

A cracked cylinder head or blown head gasket can cause engine smoke, usually coinciding with severe engine performance issues. Engine smoke is often a sign of a severely cracked engine block. A cracked engine block can also cause engine overheating. This happens when the crack is severe enough to allow engine antifreeze to leak, causing the engine temperature to rise and the engine to overheat.

A cracked cylinder head or blown head gasket can also cause low engine compression. A crack in the engine block can disrupt engine combustion pressure, lowering engine compression and causing poor engine performance.

To check for a cracked cylinder head or blown head gasket, you can remove the radiator cap and inspect for any signs of mixing between the engine's antifreeze and oil. Another way to check is to use a head gasket tester kit, which can be purchased from a local shop or online. If the tester kit confirms a damaged gasket, it is recommended to contact a professional mechanic to assist with the replacement.

It is important to act quickly if you suspect a cracked cylinder head or blown head gasket as it can cause severe engine damage if left unattended.

Oil cooler

An oil cooler is a mechanical device that removes excess heat from internal combustion engines through a heat exchanger. It is used to cool various mechanical parts, including the engine and transmission system. The device is usually located in front of the water-based radiator system and works only when the vehicle is running.

The hot engine transfers heat to the oil, which then passes through the heat exchanger (oil cooler) and is cooled before recirculating to absorb the engine's heat again. This process helps keep the engine components at their normal working temperatures, improving performance and extending their service life.

There are two main types of oil coolers: oil-to-water and oil-to-air. Oil-to-water coolers use a coolant that passes through a heat exchanger element, either adding heat to cold oil or drawing heat from hot oil. Oil-to-air coolers are smaller radiators that cool the engine oil directly using ambient air from the cooling fans.

While not all cars require specific oil cooling, it is essential to consider it when modifying a car's performance or taking it to a race track. Neglecting cooling can potentially lead to catastrophic engine failure.

Symptoms of a Failing Oil Cooler

There are several signs that may indicate a failing oil cooler:

• Leakage of the oil cooler adapter: External failure of the oil cooler adapter can force engine oil out of the engine. Small leaks may result in a puddle of oil under the engine, while larger leaks may cause a stream of oil on the ground.
• Oil in the cooling system: Internal failure of the oil cooler adapter can force oil into the cooling system, resulting in a lack of lubrication and potential engine damage.
• Leakage of engine coolant from the oil cooler: External failure of the oil cooler can force engine coolant out, leading to overheating.
• Thermostat failure: A faulty thermostat can cause either overheating or undercooling of the engine by disrupting the flow of oil into the oil cooler.

Leaky gasket head

A leaky gasket head is a common cause of antifreeze mixing with motor oil. The gasket head, or cylinder head gasket, is a thin, pre-cut template, usually made of steel, rubber, Teflon, or graphite. It sits between the cylinder head and the engine block to prevent water (antifreeze) from mixing with the motor oil. When the gasket blows or leaks, antifreeze can enter the oil pan, leading to a range of issues.

Symptoms of a Leaky Gasket Head

When antifreeze mixes with motor oil, it reduces the oil's viscosity and lubricating power. This can cause a loss of engine power and lubrication, which can lead to engine damage. One of the most noticeable signs of a leaky gasket head is a milky, frothy, or white sludge on the underside of the oil filler cap or the dipstick. This "milkshake" or "mayonnaise" is caused by the mixing of coolant and oil. The colour can vary depending on the type of coolant used, but as the engine runs, the two fluids will eventually mix, resulting in a milky liquid.

Other symptoms of a leaky gasket head include a sweet smell, which can indicate the presence of antifreeze in the oil. Continuous antifreeze drops with no visible leaks can also be a sign, as the antifreeze may be making its way into the oil crankcase.

Fixing a Leaky Gasket Head

If you suspect a leaky gasket head, it is important to act quickly to prevent severe engine damage. You can use a head gasket tester kit to confirm if the gasket is damaged. If it is, the best course of action is to contact a professional mechanic to replace the gasket. This process can be labour-intensive and expensive, costing around $1000 on average.

While gasket sealers can provide a temporary fix, they are not a permanent solution. These products can buy you some time until you can get a complete repair done by a mechanic.

Overheating

If your engine overheats, it can destroy the gasket or crack the cylinder head, allowing the oil and coolant to mix. This mixture will cause the engine to overheat further, which can lead to severe engine damage.

If you notice that your engine is overheating, it is important to act quickly to prevent further damage. Check for any leaks and inspect the head gasket for any signs of damage. If the gasket is damaged, it will need to be replaced, which can be a costly repair.

To prevent overheating, it is important to maintain your vehicle's cooling system and engine. This includes regularly checking the coolant level, ensuring the radiator is clean and free of debris, and keeping the engine well-lubricated.

Damaged engine block

A damaged engine block is one of the rarer causes of coolant mixing with oil in the oil pan. The engine block is the main structure of a combustion engine that contains the cylinders and other components. Damage to the engine block can cause severe oil leakage, which can mix with coolant.

If you have a damaged engine block, your best option is to replace the engine or the engine block. You can source a new block from a scrap yard, either locally or online, and rebuild your engine. This can be an expensive repair, and it may be more cost-effective to purchase another vehicle.

Other causes of coolant mixing with oil include a blown head gasket, a faulty oil cooler, a cracked cylinder head, and a seeping transmission cooler.

Frequently asked questions