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Your Head Gasket (Cylinder Head Gaskets) worn out? » Read more about common malfunctions • Repair • Replacement manual
Constructive vulnerability: The cylinder head gasket
An engine's head gasket is an inevitable vulnerability due to its construction. It is responsible for the lateral sealing of the combustion chamber. Due to the high temperatures and high internal pressures at the engine, the cylinder head gasket is permanently exposed to large stresses. Thus, their need to be replaced becomes more and more likely after a certain mileage.
Function and position of the engine seal
As the name suggests, the cylinder head gasket is located between the cylinder head and the short motor. Thus it seals the combustion chamber, which is defined by the pistons moving up and down on one side, and the valves on the other side. The engine seal's main task is keeping the explosion pressure contained in the cylinder and preventing it from escaping. However, many channels for lubricating oil and coolant run through the head gasket. The explosion pressure from the combustion chamber must also be sealed against these channels. Finally, the head gasket must also ensure that water and oil do not mix there.
Recognizing a defective cylinder head gasket
A blown head gasket is one of the most feared damages on a car, as their repair is usually very time-consuming and expensive. However, if damage occurs, a repair is inevitable and should be carried out as quickly as possible. The more time passes before a cylinder head gasket is repaired, the more likely it is that this issue will cause other systems in the engine to take damage.
Since the head gasket is the interface between compression, oil and coolant, all three areas of the engine may be affected by a defect. Symptoms thereof may include:
Oil and cooling channel are not sufficiently sealed: Oil in the coolant, indicated by the black coloring of the coolant in the reservoir. The same way, water might make its way inside the lubricating oil. Then, a thick, brown-white foam can be seen under the oil filler cap.
Compression chamber and oil channel are connected: Although this case is rather rare, it is not impossible. If the oil system becomes pressurized, oil can be pushed back out of the pipe for the oil dipstick or the turbocharger.
Leakage between the compression chamber and the cooling system: In this case, the compression pressure makes its way into the coolant. Cooling hoses or the reservoir can burst. However, coolant hoses will swell a lot first. The coolant will gush out of the reservoir when throttling. Bubbles form permanently when idling. The engine temperature constantly keeps increasing.
Furthermore, oil or cooling water leaking at the cylinder head gasket is a safe indication of a defective engine seal.
Repairing a cylinder head gasket
If a leaking engine seal is noticed early enough, it can still be repaired by a hobby mechanic. It is decisive whether the motor overheated or not. If it did, only parts of this repair can be performed without involving a specialist.
Before replacing the head gasket, the engine oil and coolant must be drained. Next, the valve cover and finally the cylinder head is removed. It is important to loosen the screws in the order prescribed by the manufacturer. Once the cylinder head is removed, it must be checked for evenness. A straight metal bar and a feeler gauge are used for this. The tolerances can be learned from the engine manufacturer. If evenness is out-of-tolerance due to overheating or incorrect disassembly, the head must be ground. This can only be done by a specialist company and costs about 150 euro. Once the head is removed, replacing the valve stem seals is also recommended. This is also a good opportunity to polish the inlet and outlet ports and thoroughly clean the valves. Then the new cylinder head gasket is installed according to the manufacturer's instructions. New screws and the correct torque must be used. The valve cover gasket and, if necessary, the timing belt with idler pulley or water pump are also replaced. This will result in a completely repaired engine, which can serve for many more tens of thousands of kilometers of relaxed driving. Engine seal with quality That the high costs involved in the installation of the cylinder head gasket only leave room for use of high quality parts is obvious. With cheap offers, one can assume that the another replacement will become necessary after just a few hundred kilometers. A brand name seal costs about 100 euro in the full set. This repair should be worth it.