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The cylinder head gasket (cylinder head) is designed to seal the plane between the block and the head. It also maintains the required pressure inside the oil system, preventing the oil and coolant from leaking out. The gasket needs to be changed with any intervention in this part of the engine, that is, it can be considered one-time, because when reinstalling, there is a high risk of violation of the tightness of the connection.
Replacing the cylinder head gasket performed by specialists of any service station, but if this service costs an average of about 8,000 rubles. The part itself will cost you from 100 to 1,500 or more rubles, depending on the quality of the product and the model of the car. That is, it will be much cheaper to replace it independently, and the process is, although laborious, but not critically complex.
Today, three main types of cylinder head gaskets are widely used:
- asbestos-freewhich during operation practically do not change the original shape and quickly recover after a slight deformation,
- asbestosquite resilient, resilient and able to withstand the highest temperatures,
- metalwhich are considered the most reliable, efficient and durable.
Asbestos cylinder head gasket
Asbestos-free cylinder head gasket
Cylinder head gasket
When do I need to change the cylinder head gasket?
The specific warranty period, after which the head gasket must be replaced, basically does not exist. The service life of this product depends on the model and general condition of the car engine, driving method and other factors. But there are a number of obvious signs indicating that the gasket has ceased to fully perform its functions:
- the appearance of engine oil or coolant in the connection area at the junction of the block with the head,
- the appearance of foreign light impurities in the oil, which indicates the penetration of coolant into the oil system through the gasket,
- a change in the nature of the exhaust when the engine warms up, which indicates the penetration of coolant into the cylinders,
- the appearance of oil stains in the tank with coolant.
These are the most common signs of wear or a defective cylinder head gasket. In addition, its replacement without fail is required when completely or partially dismantling the cylinder head.
Cylinder head installation: procedure and general recommendations
The first condition for the correct and reliable installation of the cylinder head is the cleanliness of the seat. Thoroughly clean the plane of the block on which the cylinder head is placed. Cleaning is first carried out with a sharp object, and then with special automotive cleaners that will help remove the remaining antifreeze, oil.
Pay particular attention to the holes into which the studs are screwed. They get oil, water, garbage. And then, when the cylinder head is attracted by the studs to the block, they can cause microcracks in the cylinder block due to the fact that when the studs are screwed in, excessive pressure is generated. When the motor is heated through these microcracks, it will push the gases, the gases will break the gasket between the cylinder head and the block, and the water from the cooling system will go into the oil. Engine overhaul is provided to you! And this is at best. Therefore, it is recommended to carefully check the holes before screwing in the studs and be sure to get them wet by taking a clean rag and using a screwdriver to get to the bottom.
When the space for the cylinder head is cleaned, proceed with installation. Installation of the cylinder head begins with the correct installation of the gasket, which is located between the cylinder head and the cylinder block.
The holes of the block must clearly coincide with the holes of the gasket, only in this case its installation is considered correct.
And the cylinder head should be well cleaned of soot, dirt, oil, antifreeze. If there is a suspicion that the cylinder head has been overheated or otherwise affected, which has led to deformation, then it is checked on a special device and then, if necessary, sanded.
When installing the cylinder head in place, it happens that the gasket “moves out”, so watch for it.
The cylinder head is considered to be installed in place when it "settled down" on the rails, and hoses, wires do not interfere with it. After this, start the screwing procedure. In order not to mix up the bolts, they must be marked in advance. The internal bolts are smeared with oil, so it is difficult to confuse them with the external ones, this will be a kind of mark.
If you do not have a pneumatic or electric tool, you can screw the cylinder head bolts with an old, good rot.
With a rotor, bolts only bait, but do not tighten completely, for this there is a special, torque wrench. Only with its help, check the correct tightening torque, which is recommended by the manufacturer.
The first tightening torque is recommended to be set at 2 kg. The main thing - be sure to adhere to a certain order of tightening bolts, in pairs from the center to the edge. In this case, the head does not warp.
The second tightening torque should not exceed 8 kg. The tightening order remains unchanged, from the center to the edges, in pairs. After the bolts are tightened by 8 kg, we carry out two dovorot, both 90 °. First we pass the bolts the first time, turning the torque wrench 90 °, then the second time.
After final tightening, the cylinder head is considered to be mechanically installed, but not yet working. To make it work, you need to connect the entire "periphery", i.e. hoses, tubes, and more. It is recommended immediately that in order not to return to this later, connect the temperature sensor wire and set the timing mark.
After proceeding with the installation of valve glasses. Before installation, they must be cleaned of dirt and lubricated. Clean and greased glasses should fit easily.
In order not to confuse the installation sequence of the glasses, removing them, they are placed in a certain order. After installing the glasses, be sure to lubricate the “bed”, on which the camshaft will then lie.
Something else useful for you:
The oiled and clean camshaft is put in place. You can fix it immediately with the gland. Experienced locksmiths, in order to simplify the process of setting the camshaft marks, still sometimes use the grandfather method. During the installation of the camshaft, the first and third camshafts must face you.
Then we replace the camshaft cover. Lubricate the places where the camshaft (bed) will lie, and do not forget about one nuance. At the ends you need to remove the old sealant, and apply a new one, then it will hold the oil well.
Installing the second part of the cover, repeat the process. Now we bait nuts, and do not forget about the washers that should be under each nut.
The tightening torque of the camshaft nuts must not exceed three kilograms. Experienced repairmen can eventually tighten without a torque wrench. Then put a tin protective cover.
Then we put on the camshaft gear, but before that make sure that you remember to put a key on the camshaft, which keeps the gear from turning.
Firmly fix the gear in place in place. Be sure to ensure that the marks on the gear and cylinder head match.
Then we put on the timing belt, but first it is recommended to put the tension roller. Install a special washer on the stock before the roller. Do not forget that the roller to the "madness" should not be tightened, it should freely rotate on the stock.
When putting on the timing belt, do not forget to check the coincidence of the marks on the camshaft gear and on the crankshaft. When the timing belt is dressed, by tightening the tension roller, we achieve the desired belt tension.
After tensioning to the desired indicator (the belt rotates around its axis by 90 °), tighten the control nut smoothly.
The following is an example of a distributor, which must be correctly installed in the grooves. It is necessary that after installing the distributor in the grooves, the alignment of the shafts is observed. We mount a gas pump between the distributor and the cylinder head, without forgetting to lubricate it with sealant. So that the stem does not rest against the camshaft, it must be pressed out with a screwdriver. The fuel pump drive housing is tightened with a hexagon.
Having pressed the case slightly with a hexagon, we bait nuts and evenly attract. Then we tighten the hexagon “seriously”. We finally install the distributor, which we only tried on before. Do not forget about the sealant, which eliminates oil leakage. Do not forget about the bar, on which there is an ignition timing, because after starting the engine, it may be necessary to adjust the distributor. Once again, we check the connection of wires and pipes that we forgot, connect.
The final touch is the installation of the valve cover and the timing belt cover. After completing all work and checks, do not forget to screw the throttle cable into place. The cylinder head is installed and ready to go.
When is a replacement required?
Replacing the cylinder head gasket may be required in two cases. The first - in the case of removal of the head for some repair work. And the second one is directly changing the gasket itself in case of loss of hermeticity. In such cases, they say that the cylinder head gasket is burnt out or the cylinder head gasket is punched.
Symptoms and consequences:
- leakage of lubricant or coolant at the junction,
- if foam is visible with a white tint when checking the lubricant composition on the dipstick, this happens if the coolant penetrates the damaged gasket,
- white exhaust gases - this happens when the coolant is in the cylinders,
- if grease spots appear in the tank or on the surface of the liquid - this is because the lubricating compound was in the vehicle’s cooling system through a damaged gasket,
- in the cooling system there are exhaust gases, again through a faulty cylinder head gasket. This is noticeable by bubbles in the radiator or in the tank,
- there may also be other symptoms and signs of loss of tightness.
For those who do not know how to change and choose a cylinder head gasket, we will describe the whole process step by step. We will also explain why it is important to follow the order of bolt tightening.
This video shows how to check the tightness of the cylinder head system and the integrity of all systems in a simple way.
- Disconnect the system by disconnecting the negative terminal of the battery.
- We expose the piston of the 1st cylinder at TDC.
- Drain the coolant.
- We reduce the pressure in the system.
- Disconnect the exhaust pipe of the muffler from the collector.
- Remove the cylinder head cover.
- Having disconnected the wires and loosened the clamps, remove the pipe with the air purifier body.
- Unscrewing and loosening the nuts, we move the bracket to the side.
- Disconnect the hoses of the cooling system.
- Disconnect draft of a drive throttle заслонки.
- Disconnect the wires from the oil sensor in the crankcase of the power unit.
- Disconnect other wires and pads.
- Dismantle the cover and belt.
- We fix the gear pulley of the shaft from possible rotation, unscrew the bolt on which it is mounted.
- Carefully remove the pulley from the shaft, making sure that the oil seal is not damaged.
- Unscrewing the bolts and nut, remove the cover, which is located at the rear.
- Remove the remaining hoses, pads and wires.
- According to the scheme, we loosen the tightening of 10 cylinder head bolts with the “Torx” key.
- Unscrew all the bolts completely.
- You need to remove it with washers.
- Dismantle the head.
- Now you can remove the cylinder head gasket.
- Immediately measure the bolts, if they are very extended, then it is probably better to change them.
- Clean the surfaces that will come in contact with the gasket.
- Now you can put a new gasket. When installing, make sure that the hole through which the oil passes is between the third and fourth cylinders.
- We put the cylinder head, while you need to make sure that the shafts are at top dead center.
- Tighten the bolts, observing the following scheme, otherwise there may be unpleasant consequences that cross out all the work in such a way that the tightness is broken.
- Also observe the moment. It is individual for each car model.
- Install the removed hoses, tubes, pads and wires in the reverse order of removal.
- This completes the replacement.
Be sure to observe and check during the ride how the system works and functions and whether the tightness is ensured and if there are any negative signs.
Replacing the cylinder head gasket yourself is not too complicated, but since this is an important part, you need to do everything here carefully and accurately. All work is carried out in several stages:
1) Disconnecting all attachments, pipelines and other parts that interfere with the removal of the cylinder head.
2) Cleaning the head bolts from oil and dirt to ensure the convenience and safety of the key.
3) Loosen the mounting bolts, and it should start from the middle, turning each bolt at most one full revolution at a time to relieve stress.
4) Removing the block head and removing the old gasket.
5) Cleaning the seat and installing a new cylinder head gasket, and it should sit on all the guide bushings and correspond to the marked alignment grooves.
6) Putting the head in place and tightening the bolts, which is carried out exclusively with a torque wrench and only according to the diagram given by the manufacturer for your car model, since it is important that the bolts are tightened exactly with the optimum torque settings for your engine.
When the engine is assembled, you can install and reconnect all attachments. AT the first days should be observedif there are any signs of a gasket defect described in the list above.
The cost of installing the cylinder head gasket
If you learn to change the cylinder head gasket yourself, ensuring the tightness of the system, you can save a decent amount. For those who do not know how much it costs to replace the cylinder head gasket, we will tell you that the amount of work itself can be in the range from 170 to 400 dollars, depending on the brand of car. Also, it will be expensive to simply replace the cylinder head gasket.