If you suspect that coolant is somehow leaking into the engine oil in your car then this could be a serious problem that can cause significant damage if it’s not fixed.
Coolant mixed with oil in an engine will have a milky or foamy appearance. This is due to the fact that oil and coolant have different viscosities, and when they mix, they can create a frothy or milky substance. The milky appearance is caused by the emulsification of the oil and coolant, which can occur when the engine is running and the two fluids are agitated.
If you suspect that your engine has coolant mixed with oil, you can check the oil dipstick for signs of the milky or foamy substance. You may also notice a sweet smell coming from the engine or exhaust if it is burning coolant, or the engine may be running poorly or overheating.
The most common cause of coolant leak into engine oil is a blown head gasket. When the head gasket fails, coolant can leak into the oil passages, causing the oil to become contaminated. Other possible causes of coolant leak into engine oil include a cracked cylinder head, a damaged engine block, or a damaged oil cooler.
5 Common Reasons Why Coolant Leaks into Engine Oil
When coolant leaks into engine oil, it can cause serious damage to the engine and reduce its lifespan considerably.
There are several reasons why this can happen, including:
1. A Blown Cylinder Head Gasket
A blown cylinder head gasket can cause coolant to leak into the engine oil. The cylinder head gasket is responsible for sealing the engine’s combustion chambers and preventing coolant from leaking into the engine’s cylinders.
If the head gasket is damaged or blown, it can allow coolant to leak into the engine’s combustion chamber, where it is burned and expelled through the exhaust system. This can cause a loss of coolant without any visible external leaks.
A leaking cylinder head gasket can also allow coolant to leak into the engine oil passages. The cylinder head gasket sits between the engine block and the cylinder head and seals the coolant passages from the oil passages.
If the head gasket is damaged, it can allow coolant to leak into the oil passages, which can cause the oil to become contaminated with coolant. This can cause a drop in engine oil pressure and lead to engine damage.
This is a common cause of coolant leaks and can be identified by checking the oil for signs of coolant contamination, such as a milky white appearance.
2. A Cracked Engine Block
A cracked engine block can cause coolant to leak into the engine oil. The engine block is responsible for housing the engine’s cylinders, coolant passages, and oil passages. If the engine block is cracked, it can allow coolant to leak into the engine’s oil passages, which can cause the oil to become contaminated with coolant.
A damaged engine block can also allow coolant to leak into the engine’s combustion chambers, where it will burn up and be expelled through the exhaust system. This can cause a loss of coolant without any visible external leaks that can lead to engine overheating.
If you suspect that your engine has a cracked engine block, it is important to have it inspected because ignoring a cracked engine block can cause serious damage to the engine and other components, and can potentially lead to engine failure
3. A Damaged Cylinder Head
A damaged cylinder head can also cause coolant to leak into the engine oil. The cylinder head is responsible for sealing the engine’s combustion chambers and preventing coolant from leaking into the engine’s cylinders.
If the cylinder head is warped or damaged, it will no longer form a proper seal with the engine block and this can allow coolant to leak into the engine’s combustion chambers, where it is burned and expelled through the exhaust system.
The cylinder head sits on top of the engine block and contains the valves, camshaft, and other engine components. If the cylinder head is damaged, coolant can leak into the oil passages, which can cause the oil to become contaminated with coolant. This can cause a drop in engine oil pressure and a reduction in its ability to lubricate the engine.
Damage to the cylinder head will occur mainly because of overheating or other mechanical failures. If the cylinder head is damaged, it will usually need to be replaced to prevent further damage to the engine.
4. A Failed Oil Cooler
A failed oil cooler can cause coolant to leak into the engine oil.
An oil cooler is a device that helps regulate engine temperature by transferring heat away from the engine oil. The oil cooler is typically located near the engine’s coolant system and is responsible for cooling the engine oil and preventing it from overheating.
The oil cooler works by circulating engine oil through a series of small tubes or fins, which are designed to increase the surface area of the oil and allow heat to dissipate more quickly.
As the engine oil flows through the tubes or fins, it is cooled by air or coolant that passes over the surface of the tubes or fins. This helps to regulate the temperature of the engine oil and prevent it from becoming too hot.
Some oil coolers are designed to circulate engine oil through a separate cooling system, while others are integrated into the engine’s existing cooling system. Oil coolers can be air-cooled or liquid-cooled, depending on the design of the engine and the oil cooler.
The oil cooler is typically located near the engine’s coolant system, and if it fails, it can allow coolant to leak into the oil passages. This can cause the oil to become contaminated with coolant.
5. Corroded or Damaged Cylinder Liners
Corroded or damaged cylinder liners can cause coolant to leak into the engine oil. The cylinder liners are responsible for forming the inner walls of the engine’s cylinders and providing a smooth surface for the piston to move against.
If the cylinder liners are corroded or damaged, they can allow coolant to leak into the engine’s oil passages.
Corrosion or damage to the cylinder liners can cause pitting or cavitation on the surface of the liner. This can create small holes or cavities that allow coolant to leak into the engine’s oil passages.
Over time, the coolant can mix with the engine oil, which can cause a drop in engine oil pressure and leave the oil less effective at lubricating the engine.
What Are The Symptoms of A Coolant Leak into Engine Oil?
A coolant leak into the engine oil can cause serious damage to an engine if left untreated. It can lead to a drop in engine oil pressure, engine damage, and even engine failure. It is important to be aware of the symptoms of a coolant leak into engine oil so that you can identify the issue and have it repaired as soon as possible.
Here are some of the most common symptoms in detail:
1. Milky or Foamy Oil
When coolant leaks into the engine oil, it can create a milky or foamy substance on the oil dipstick or oil cap.
The milky or foamy appearance is caused by the emulsification of the oil and coolant, which can occur when the engine is running and the two fluids are agitated. The milky appearance is due to the fact that oil and coolant have different viscosities, and when they mix, they can create a frothy or milky substance.
If you notice a milky or foamy substance on your oil dipstick or oil cap, it is a clear indication that coolant has mixed with the engine oil.
This can cause a drop in engine oil pressure and engine damage. It is important to have any coolant mixed with oil issue addressed by a professional mechanic as soon as possible. Ignoring this issue can cause serious damage to the engine and other components, and can potentially lead to engine failure.
2. Engine Overheating
If the coolant is leaking into the engine oil, it can cause the engine to overheat.
The coolant is responsible for regulating the engine temperature and preventing it from overheating. If the coolant is leaking into the engine oil, it can cause the coolant level to drop, which can lead to engine overheating and damage.
When the engine overheats, it can cause damage to the engine components, such as the cylinder head gasket or cylinder head.
Engine oil that mixes with coolant will also lose it’s ability to cool the engine. It can also cause the engine oil to break down and lose its lubricating properties, which can cause further engine damage.
3. Low Coolant Level
Another symptom of a coolant leak into engine oil is a low coolant level. This happens because the coolant is leaking into the engine oil and not staying in the cooling system where it belongs.
If coolant is leaking into the engine oil, it will almost certainly lead to engine overheating and damage. The most common symptom of a low coolant level is a coolant level warning symbol on the dashboard, engine overheating and decreased fuel economy,
4. White Smoke From Exhaust
If you notice white smoke coming from your exhaust, it could be a sign of a coolant leak into engine oil.
When coolant leaks into the engine oil, it can also leak into the engine cylinders if the head gasket has been compromised.
This can cause the coolant to burn in the combustion chamber, which can create white smoke coming from the exhaust pipe. The white smoke is caused by the steam that is produced when the coolant is burned in the combustion chamber.
In addition to white smoke, a coolant leak into engine oil can cause other symptoms such as milky or foamy oil, sweet smell, engine overheating, and low coolant level.
5. Engine Misfires
If the coolant is leaking into the engine oil, it can cause the engine to misfire. This is because the coolant can damage the spark plugs and leave them unable to spark properly. If you notice that your engine is misfiring, it’s important to get it checked out by a mechanic to determine the cause of the problem.
What Happens When Coolant Mixes with Oil?
When coolant mixes with engine oil, it can cause a variety of problems. The two fluids have different functions and properties, and when they mix, they can create a harmful mixture that can damage the engine.
Here are some of the things that can happen when coolant mixes with engine oil:
- Reduced Lubrication: Coolant is not designed to lubricate engine parts like oil does. When coolant mixes with oil, it can reduce the lubricating properties of the oil, which can cause increased friction and wear on engine parts. This can lead to engine damage and decreased engine performance.
- Sludge Formation: Coolant and oil can mix to create a sludge-like substance that can clog oil passages and reduce oil flow. This can cause a decrease in oil pressure and can lead to engine damage or failure.
- Corrosion: Coolant contains chemicals that can corrode engine parts. When coolant mixes with oil, it can cause corrosion in the engine, which can lead to leaks and other problems.
- Overheating: Coolant is designed to help regulate engine temperature. When coolant mixes with oil, it can reduce the cooling properties of the coolant, which can cause the engine to overheat.
Overall, when coolant mixes with engine oil, it can cause a variety of problems that can lead to engine damage or failure. It is important to address this issue as soon as possible to prevent further damage to the engine.
How to Diagnose and Fix Coolant Leak into Engine Oil
When a coolant leak into the engine oil is suspected, it is important to diagnose and fix the issue as soon as possible to prevent further damage to the engine.
A coolant leak into engine oil can cause significant damage to an engine if not diagnosed and fixed promptly.
The best place to start is with an OBD diagnostic readout of any error codes stored in the ECU. This issue can trigger error codes such as P0115 (Engine Coolant Temperature Circuit Malfunction), P0125 (Insufficient Coolant Temperature for Closed Loop Fuel Control), and P1281 (Engine is Cold Too Long).
If oil is leaking internally within the engine then it is not an easy problem to repair. Here are a few possible solutions that may be needed to fix the problem if the engine has not been damaged beyond repair.
1. Replace Head Gasket
One of the most common causes of coolant leaking into the engine oil is a blown head gasket. Symptoms of a blown head gasket include white smoke coming from the exhaust pipe, overheating, and loss of power.
To replace the head gasket, the engine head must be removed and the old gasket scraped off. The new gasket is then installed and the engine head is reattached.
2. Repair the Engine Block
If the engine block is cracked, it will need to be repaired or replaced. Symptoms of a cracked engine block include coolant leaking into the engine oil, overheating, and loss of power.
To repair the engine block, it must be removed from the vehicle and taken to a machine shop for repair. If the damage is too severe, the engine block may need to be replaced.
3. Replace the Cylinder Head
If the cylinder head is cracked, it will need to be replaced. Symptoms of a cracked cylinder head include coolant leaking into the engine oil, overheating, and loss of power.
To replace the cylinder head, the engine head must be removed and the old cylinder head removed. The new cylinder head is then installed and the engine head is reattached.
4. Flush the Engine
After the coolant leak into the engine oil has been fixed, it is important to flush the engine to remove any remaining coolant from the oil system. This can be done by draining the oil and replacing it with fresh oil.
The engine should then be started and run for a few minutes before the oil is drained again. This process should be repeated until the oil is clear and free of coolant.
Preventive Measures – How To Stop Engine Oil From Mixing With Coolant
- Regularly check the coolant level in the engine and ensure it is at the recommended level.
- Ensure that the engine oil level is also at the recommended level and change it regularly.
- Replace the engine oil filter regularly.
- Ensure that the engine cooling system is working correctly, and the radiator is not clogged.
- Ensure that the engine does not overheat by maintaining the correct operating temperature.
- Use the recommended engine coolant and change it at the recommended intervals.
- Ensure that the engine oil and coolant are not mixing by checking the engine oil dipstick regularly.
