Why is my engine oil mixed with coolant?
Engine oil mixed with radiator coolant can damage the engine. The engine oil's chemical structure will change, so engine oil loses all its functions. For example, as a lubricant, as a coolant, sealer, and others (read more on engine oil functions ).
When engine oil loses all its functions, the engine components that work will rub against each other. The engine will wear out, heat up quickly, and are very easily damaged. The following is an example of damage due to radiator coolant mixed with oil:
- Damage to the crankshaft bearings and main bearings
- Damage to the camshaft and valve mechanism
- Damage to cylinder block walls, piston rings, and pistons
- Damage to the oil pump
- And others
As a result, you will need more costs to repairs your car engine. To find out earlier about the problem of engine oil mixed with radiator coolant, here are some of the characteristics that we can know before:
- The engine oil color will be light brown like coffee milk (can be seen from the oil stick or top cover)
- A foam appears with light brown froth on the radiator.
- The engine sound sounds harsher and noisier when used.
- Radiator coolant continues to decrease.
- And others
So what causes this oil mixed with coolant? This article will share information about what causes engine oil to mix with coolant, along with tips for overcoming it.
1. Bent/curved cylinder head
The first cause of engine oil mixed with coolant is a bent cylinder head. The bent cylinder head generally occurs due to an engine overheat. This bent cylinder head will create a gap between the cylinder head gasket and the cylinder block.
The pressurized coolant inside the engine water jacket will come out of the gap and enter the engine oil main gallery. When the coolant enters the engine continuously, it makes the oil mixed with coolant.
It is necessary to dismantle the engine cylinder head to overcome the curved cylinder head. After dismantling, we need to measure the cylinder head flatness and curvature degree that occurs on its surface. Yes, this curved engine cylinder head has a curvature limit.
If the curvature's size is still below the manufacturer's recommended limit, then do the fly-cutting cylinder head surface or doing a re-surface; it can be the solution. However, if you have crossed the surface curvature limit, changing the cylinder head with the new one is the best solution.
2. Crack in the cylinder head's water jacket wall
The next cause of engine oil mixed with coolant is a crack in the cylinder head's water jacket wall. The problem of water jacket wall cracks on the cylinder head is commonly found in old cars, but brand new cars can also experience this problem.
The cracks are caused by the erosion of the cylinder head walls due to coolant use, which is not suitable for engine characteristics.
In some cases, the coolant is often saturated and contains solid crystals because it has never been replaced or uses a coolant that does not comply with the manufacturer's recommendations.
The dirt will continue to flow due to the circulation of coolant. These solid crystals will gradually cause a crushing effect on the cylinder walls, causing the cylinder head walls to tip until cracks appear.
These cracks then make the coolant out and flow into the engine, so engine oil mixed with coolant.
3. Crack in the cylinder block's water jacket wall
The next cause of engine oil mixed with coolant is a crack in the cylinder block's water jacket wall. These conditions and problems are similar to the cracks in the cylinder head, but this time, the crack occurs in the cylinder block's water jacket wall.
Cracked problems in the wall water jacket on the cylinder block are very rare. As long as we are a mechanic, we have only found a case like this once.
The crack is right in the wall near the bottom of the cylinder liner. Of course, this leak will cause the coolant to drip down directly and mix with engine oil.
The best way to overcome is to get off the engine, then patch the crack. If it is not possible, replacing the cylinder block is the best final solution that can be done.
Also read:4. The cylinder head gasket is damage
The cause of engine oil mixed with coolant, which also often happens is when the cylinder head gasket is damaged. Damage to the cylinder head gasket is rare because it is clamped between the Cylinder Head and the Cylinder Block.
However, there are times when the cylinder head gasket is damaged in the water jacket holes. This part often experiences corrosion so that coolant penetrates the hole and flows into the oil. As a result, the coolant enters the engine and mixes with engine oil.
5. Core plugs are porous and leaking.
The cause of engine oil mixed with coolant has resulted from a porous and leaking core plug. Core plug is a water jacket covering cap component commonly installed on the cylinder block and the cylinder head. The function of this core plug is to prevent coolant leakage.
Especially for engine oil mixed with coolant problems, this porous and leaking core plug generally occurs in the cylinder head. Several cylinder heads have core plugs. Commonly, it's located just below the camshaft component.
Because it is made of metal, this core plug can be porous and leak so that the coolant will come out of the water jacket on the cylinder head. Then the coolant enters the engine oil reservoir. As a result, the engine oil will mix with coolant.
The best way to deal with oil mixed with coolant due to leaky core plugs is to replace the leaking core plug with new ones.
6. Leaking in the oil cooler
The last cause of engine oil mixed with coolant that we knew about was a leak in the oil cooler. Please note that not all cars use a water-cooled oil cooler.
The oil cooler functions to cool the engine oil temperature before it is circulated into the engine. The goal is to make the engine oil cool again and function more optimally as a coolant for friction components.
Water-cooled oil coolers are often the cause of engine oil mixed with coolant. Usually, this problem occurs because the gasket / o-ring separating the engine oil and coolant is damaged and leaks. The effect is engine oil will mix with coolant.
To overcome the mixing of coolant with engine oil due to a leak in the oil cooler, replacing the oil cooler o-ring is necessary. If it still leaks, oil cooler replacement as an assembly is certainly the last option.