Replacing the front and rear crankshaft oil seal

During operation, the car engine endures various loads with constant variability of operating modes. To ensure the performance of internal combustion engines, a significant reduction in friction, wear of parts, as well as to avoid overheating, a special engine oil is used. The oil in the motor is supplied under pressure, gravity and splashing. A reasonable question is how to ensure the tightness of the engine so that the oil does not leak out of it? For this, there are oil seals installed, first of all, in front and behind the crankshaft. 

In the article, we will consider the design features of the crankshaft oil seals, determine the causes and characteristics of their wear, and also figure out how to replace these oil seals on our own.

Description and function of the crankshaft oil seal

So, for the normal functioning of an automobile engine, high-quality and constant lubrication of rubbing parts is needed. One of the main elements of the motor is the crankshaft, both ends of which protrude outwards. The crankshaft is lubricated under high pressure, which means that a high-quality seal is required on both sides. These seals act as seals. In total, two seals are used:

• the front, usually smaller, is installed behind the crankshaft pulley in the front cover. Can be integrated into the oil pump;
• the posterior is usually large. Located behind the flywheel, sometimes it changes with the aluminum cover, it ensures tightness without letting oil into the clutch housing or gearbox.

What it looks like and where is installed

Fluoroelastomer or silicone is used as a material of manufacture. Previously, stuffing box packing was used as a rear oil seal, but it has the ability to pass oil when the engine is running at high speeds. The shape of the oil seals is round, and the above materials from which they are made allow not to lose elasticity in a wide temperature range. The diameter of the gland must be such that it fits snugly against the surfaces on all sides. 

Also, oil seals can be installed on camshafts if they are driven by a belt. Typically, the camshaft oil seal is the same size as the front crankshaft oil seal.

It is important, when buying new oil seals, to choose quality manufacturers, and also observe the following points:

• the presence of a spring inside the gland;
• there should be notches on the edge, they are called "oil-distilling", and also protect against dust from entering the very edge;
• the notches on the gland must be directed in the direction of rotation of the shaft.

 Crankshaft oil seal wear: causes and consequences

According to the regulations, the average service life of oil seals is about 100 kilometers, provided that the car was operated in normal conditions, and also undergoes maintenance in a timely manner, and the engine did not work at a critical temperature.

What are the causes of the oil seal failure:

• damage to the oil seal due to untimely oil change or the ingress of foreign small particles that are transported by oil, damaged the surface of the oil seal;
• overheating of the engine or its long operation at a critical temperature. Here the stuffing box begins to slowly “tan”, and when the temperature drops, it loses its elasticity, the oil begins to leak;
• poor quality product. This is often due to the quality of the material, the use of a weak spring, improperly applied notches and the deformed shape of the oil seal itself, which does not go around the crankshaft flange;
• due to the increased pressure in the lubrication system (a large amount of crankcase gases), as well as an excessively high oil level squeezes out the oil seals, since the oil has nowhere to go, and the pressure comes out in the most vulnerable place, but if the oil seals are of high quality, then the oil can come out of the gaskets ;
• incorrect installation of a new oil seal. Before installation, you must read the installation instructions so that the inside of the gland does not bite. By the way, there are Teflon oil seals, the installation of which requires the necessary skills and special tools, but more on that later.

The main consequence of crankshaft oil seal wear is a decrease in oil level. If the oil seal only sweats, then you can operate the car for some time, otherwise an urgent replacement of the oil seal is necessary. In addition to the fact that an insufficient oil level directly harms it and reduces the life of the rubbing surfaces of parts, oil pollutes the engine compartment, damages the service and timing belt, which can lead to serious consequences.

Diagnosis of oil leakage through the crankshaft oil seals

Some engines already from the first kilometer consume a certain amount of oil set by the manufacturer's regulations. After 100 kilometers, oil consumption rises to 000 liter per 1 km, which is also considered the norm. 

First of all, diagnostics are performed in the form of a surface inspection of the engine for leaks, if the oil level drops suspiciously sharply. When the engine is running, we pay attention to the color of the exhaust, if it is not gray, turn off the engine, open the radiator cap or expansion tank, and take the coolant for a sample. If the antifreeze smells like oil, and an oil emulsion is also present, the cylinder head gasket is more likely to be worn out.

In the absence of visible reasons for oil consumption, we raise the car on a lift and inspect it from the front and rear. Oil leakage from under the seals makes itself felt by a leak from the front cover, as well as the presence of oil stains on the suspension parts, since the oil splashes when it gets on the belt. The wear of the rear oil seal is more difficult to diagnose, since the gearbox input shaft oil seal is located in this area. You can determine the leakage of a certain sealant by smell, because engine and transmission oil differ sharply in smell (the second one smells like garlic).

If it is not possible to determine the area of ​​leakage, wash the engine, drive a certain number of kilometers and again inspect the unit in the area of ​​the seals.

Replacing the front oil seal + Video

To replace the front crankshaft oil seal, you must stock up on a minimum set of tools, a clean rag, a degreaser (you can use a carburetor cleaner). Depending on the design features of the engine, the process for replacing the oil seal may differ. For our example, let's take an average car with a transverse engine.

Step-by-step process for removing the front oil seal:

• shift the 5th gear lever and put the car on the hand brake;
• before removing the right wheel, or lifting the car on a lift, you need to ask the assistant to press the brake while you rip off the crankshaft pulley nut;
• remove the wheel by opening access to the pulley;
• depending on the type of tension of the service belt, it is necessary to remove it (by pulling the tensioner or loosening the generator);
• if the engine has a timing belt drive, you need to dismantle the crankshaft gear;
• on the toe of the crankshaft, as a rule, there is a key, which will interfere with dismantling and installation work. You can remove it using forceps or pliers;
• now, when the oil seal is in front of you, it is necessary to clean the surface of the crankshaft with a special spray, and also to clean all dirty and oily places with a rag;
• using a screwdriver, we pry the oil seal and remove it, after which we treat the seat with a spray cleaner;
• if we have a regular oil seal, then we lubricate the working surface with engine oil, and put on a new oil seal, and an old oil seal can be used as a cage;
• the new part must fit tightly, be sure to make sure that the inner part (edge) does not wrap, after installation the oil seal should not protrude beyond the plane of the front motor cover;
• then the assembly is carried out in the reverse order, after which it is necessary to bring the oil level to normal and start the engine, after some time check the tightness.

For a complete understanding of the process of replacing the front crankshaft oil seal, I recommend that you read the following video.

replacing the crankshaft oil seal vaz 8kl

Rear oil seal replacement + Video

Unlike replacing the front, replacing the rear oil seal is a more labor-intensive process. This is due to the fact that this will require the dismantling of the gearbox, clutch and flywheel. I strongly recommend that you immediately purchase the input shaft oil seal so that in the future you do not have to remove the gearbox specifically to replace it. 

The process of replacing the main oil seal of the crankshaft:

• we prepare the necessary tool, throw off the negative terminal from the battery and prepare to dismantle the gearbox;
• disconnect the gear selection mechanism or the working brake cylinder from the gearbox housing;
• we tear off the wheel nut, we lift the car on a lift, or if you are in a pit, then we raise the necessary side and remove the front left wheel;
• unscrew the hub nut, then disconnect the ball bearing of the lever, and move the steering knuckle to the side so as to release the axle shaft from it;
• dismantling of the semiaxis is carried out by pulling it out of the gearbox;
• after making sure that all sensors and other attachments are disconnected from the transmission, proceed to disconnect the transmission from the power unit;
• having unscrewed all the bolts of the gearbox from the engine (at least 10), using a pry bar, we pry the gearbox and pull it out of the seat. This will require at least one assistant, because the weight of the gearbox is at least 30 kilograms;
• after removing the gearbox, focus on the condition of the input shaft oil seal, and preferably replace it, even if there are no signs of fogging, but the mileage of the car has overcome the 100 kilometer mark;
• then it is necessary to remove the basket and the clutch disc, which are attached with 6 bolts to the flywheel;
• after dismantling the clutch package, a flywheel appears in front of us, which is also attached to the crankshaft flange with six reinforced bolts, and to unscrew them, it is necessary to fix the flywheel in order to avoid turning;
• by unscrewing the flywheel we get to the rear oil seal of the crankshaft. Depending on the design, it is changed as a separate spare part, or together with a metal flange. We make similar measures to clean the seat, remove the oil seal in the same way as the front one and install a new one in the same way;
• further installation is carried out in the reverse order.

For a clearer understanding of replacing the crankshaft rear oil seal, check out this video.

Replacing the rear oil seal of the crankshaft of the VAZ-2101-2107 engine.

Features of replacing the Teflon crankshaft oil seal

In addition to conventional fluororubber oil seals, there are analogues, the cost of which exceeds 1.5-2 times - oil seals with a Teflon ring. The peculiarity of installing such an oil seal is that it is installed exclusively on a cleaned surface and with the help of a special upsetting mandrel. After installation, you need to wait 4 hours, during which time the oil seal will “sit down” on its own, the main thing is not to rotate the crankshaft during this time. 

When to change oil seals

Replacement of oil seals is carried out in three cases:

• severe overheating of the motor;
• abundant leakage of oil and under the oil seals;
• overhaul of the internal combustion engine.

It is imperative to purchase quality oil seals. Speaking of the front oil seal, analogs such as Elring and Glaser can be used, because in which case it is easier to replace them. The rear oil seal, it is advisable to purchase the original production, however, the high price makes motorists stop choosing an analogue, which may soon turn into an unplanned replacement of the main oil seal.

 To summarize

So, crankshaft oil seals are critical parts that ensure the tightness of the lubrication system and protect the crankshaft flanges from dust. It is extremely important not to miss the moment of oil leakage from under the seals so that the engine is not damaged from insufficient oil levels. It is enough to visually inspect the engine for oil and coolant leaks at each MOT to always be confident in your car. 

Questions and answers:

When to change the front crankshaft oil seal? The average working life of the crankshaft oil seals is about three years, or when the vehicle's mileage reaches 100-150 thousand kilometers. If they do not leak, it is still recommended to replace them.

Where is the front crankshaft oil seal? This is a crankshaft seal that prevents oil leakage. The front oil seal is located on the crankshaft pulley on the side of the generator and timing belt.

Why is the front crankshaft oil seal leaking? Primarily due to natural wear and tear. Prolonged downtime, especially outdoors in winter. Manufacturing defects. Incorrect installation. Excessive crankcase gas pressure.