9 Common causes of oil leak under car

9 Common causes of oil leak under car - Oil leak under the car engine often makes you worry and upset. The worry is if the oil in this engine runs out without us knowing, the consequences will be fatal for the engine. At the same time, we will feel frustrated because the garage floor will always be dirty with oil every time the car is parked.

Detecting the cause of leaking oil under the car should indeed be done by a mechanic you trust. There are so many causes of oil leaks under the car that occur. If it is done only by guessing, the repairing is also not optimal. As a result, the car is damaged, the cost and time of repair will also increase.

So, continue to follow the article below, which contains information about the cause of oil leaks under the car engine. However, this article will give you an idea of what causes oil to leak under the car engine. Which parts are often the cause?

1. The oil pan drain plug and gasket are damage

The first cause of the oil leak under the car engine is the oil drain plug and the gasket being damaged. This oil drain plug is an oil drain bolt attached to the oil pan. Generally, oil leaks occur due to worn-out oil bolt threads.

We can see the factors of this seepage oil drain plug from the appearance of oil drips around the bolt. If the damage is severe, we can find oil seeping all over the oil pan and leaking onto the floor in large quantities. In addition to oil droplets, another characteristic of the oil pan drain plug is that we cannot tighten it anymore.

To overcome the cause of oil leaking under the car engine due to a damaged oil drain plug, we need to re-fix the plug thread in the oil pan. If it is still possible, it can be re-drained immediately, or we must dismantle the oil pan from the engine and take it to a lathe for thread replacement.

2. Oil pan seal and gasket are damaged

The second cause of oil leak under the car engine is a damaged gasket and oil pan seal. Oil pan seals and gaskets on each car are different. Some use Form In Place Gasket (liquid), and some use rubber gaskets. Over time, the gaskets and seals on this oil pan can damage gradually. As a result, engine oil seeps to drip onto the floor.

The position of the oil drop is very dependent on the leak's location and the lowest part where the oil flows. The characteristics of a damaged oil pan gasket will usually reveal oil seepage that covers almost the entire outer surface of the oil pan. Even in the detected part, seepage will be seen more and make the engine oil pan looks wet.

The best way to deal with an oil leak under the car engine due to the leaking oil pan gasket is to replace the oil pan gasket with a new gasket. To do this, you need to drain the engine oil first before disassembling the oil pan to replace the seal.

3. Oil filter gasket is damaged

The next cause of oil leak under the car engine is the result of a damaged oil filter gasket. It is often encountered when the oil filter gasket hardens quickly, creating a gap between the oil filter casing and the oil filter. This open gap causes engine oil to seep out. The engine oil will drip onto the floor if the gap is too wide.

The damaged or loose oil filter gasket is usually indicated by the oil filter being covered by engine oil seepage. In addition, the oil filter can be rotated easily by hand.

To fix this, try to tighten the oil filter first. If the oil filter feels tight but the oil is still leaking, possibilities are the gasket is damaged, and you need to replace the oil filter with a new one.

4. Oil pressure switch sensor is leaking

The cause of the oil leak under the next engine is the oil pressure switch sensor having seeped or leaked. It is rare because the OEM oil pressure switch sensor has been made with good quality standards. In addition, fasteners are often added to prevent oil from seeping or leaking from the sensor hole in the installation.

However, we often find replacement switches that do not follow proper installation procedures, so that engine oil seeps around the sensor. The oil pressure sensor seepage symptom can be seen from the end of the sensor body, which has engine oil seepage.

To fix this, you can add fasteners or liquid gaskets to the sensor threads before the sensor is installed. In that way, we can resolve the problem of seeping oil.

5. Cylinder head cover gasket is leaking

The next cause of oil leak under the car engine is the result of the cylinder head cover gasket being damaged and seeping. The cylinder head cover gasket is a gasket that acts as an insulator between the cylinder head and the cylinder head cover. This gasket prevents engine oil circulating in the valve train from escaping through the cap and the cylinder head gap.

Usually, within 3 to 5 years, this gasket will harden by itself, and when the gasket hardens, engine oil can easily seep and drip to the floor. The symptom of this cylinder head gasket being damaged is engine oil seeping around the cylinder head cover. Even if the seepage is severe enough, the oil will seep into the engine block, oil pan, and drip onto the floor.

The best way to fix this is to replace the leaking cylinder head gasket with a new gasket.

6. The distributor gasket or camshaft position sensor is damaged

For old generation car engines that still use a distributor, in the cylinder head section, there is generally a distributor mounted using an o-ring. This distributor O-ring is also often damaged and can cause engine oil to seep until it drips onto the floor.

As for the latest generation engines, generally, no distributors are used, but a CMP sensor (camshaft sensor) is installed using an o-ring. If the o-ring on this sensor is hardened or damaged, engine oil can also seep and drip onto the floor.

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7. Engine oil seals are worn-out

The next cause of oil leak under the engine is the result of damaged engine oil seals. At least in the engine section, several engine oil seals are installed. Here are some examples of engine oil seals commonly installed in engines.

Camshaft oil seal, installed in the camshaft position on the timing belt or timing chain
Crankshaft oil seal, mounted on the crankshaft, position on the timing belt or timing chain
Balance shaft oil seal, mounted on the balance shaft, position on the timing belt or timing chain
Oil pump oil seal, installed in the oil pump, position on the timing belt or timing chain
Rear engine oil seal, mounted on the rear crankshaft, position near the flywheel

Oil seals can also be damaged, hardened, and worn. If damaged, engine oil can seep and drip onto the floor. The position of the engine oil drop due to the damaged engine oil seal depends on the engine's model and position in the engine room. But for simplicity, you can see in the following way.

If oil drips from the part near the timing belt or timing chain, it means oil is leaking from the front engine oil seals.
If oil drips from the transmission and the engine connection, it means oil is leaking from the rear engine oil seal.

For repairs, you need an experienced mechanic who can overcome the problem of oil seeping into both parts.

8. Engine shaft worn-out

The other cause of the oil leak under the car engine is the worn-out engine shaft that is in contact with the engine oil seal. There are at least two engine shafts installed in a car engine, the crankshaft, and the camshaft. But for today's modern cars, the number of shafts can be many. There is a balance shaft, an oil pump, an injection pump, etc.

Each shaft is usually fitted with an oil seal at the end. Well, the end of the shaft that is in contact with the lip of the oil seal can also wear out. The wear and tear that occurs can result in engine oil leakage.

Disassembly and inspection of each shaft are necessary to determine which shaft is worn and causing a leak. Use experienced mechanics to solve this problem.

9. The transmission axle seals are damage

The last cause of oil leak under car engine is the result of a damaged axle seal in the transmission. The axle seals in the transmission can only be found on cars with front-wheel-drive (FWD). These seals are installed in the transmission section connected to the axle. Usually, these seals are strong enough to last for several years. But in time, this seal can also experience leakage and damage.

For cars with manual transmissions, the leaking oil is usually thicker and yellow to greenish (but depending on the color of the transmission oil used previously). If the car is an automatic transmission, most of the oil drip will be a little reddish. It can also be greenish (for CVT transmission). But for sure, the location of this oil drop is right under the transmission.

Those are some examples of the causes of oil leaks under the car engine, which we know is the most common cause in cars. Hopefully, this article can be helpful for all of you.