If you have ever unmounted the car engine o separated the cylinder head from the engine block most of the time to change the cylinder head gasket that was burned or used excessively, or for other common reasons such as the car consuming too much oil or coolant, you may have noticed that the cylinder head does not look good, and after you do a flatness test you will notice that it is warped or deformed, not always, but most of the time.
Why is the cylinder head warped?
Usually, this phenomenon happens due to engine overheating, so the main cause is poor or insufficient engine cooling.
The main causes that lead to insufficient cooling of the engine are:
- poor quality oil,
- poor quality coolant,
- either the engine has been modified excessively, especially in stage 2, stage 3 and the cooling system to support this degree of performance has not been modified.
When you want to increase the performance of the engine, known as stage 1, stage 2, stage 3, etc., then, to support these upgrades, you automatically need other parts that are much more efficient to support this performance increase, but if you have the same water pump, you have the same engine radiator, you have a weak coolant, you drive very aggressively and you strongly heated the engine, then the inevitable result will be that you will warp or deform the cylinder head.
Another cause of a warped cylinder head is that many engine manufacturers require that the cylinder head bolts should be tightened to prescribed intervals, and if you do not do so, the screws can easily loosen and the cylinder head may develop flares that generate the cylinder warping phenomenon. or the engine block.
Once the screws are loosened, the cylinder head can bend and twist, and the cylinder head gasket can no longer properly seal and either affect the compression of the engine or allow water or oil to leak inside or outside the cylinders.
If the cylinder head gasket allows for compression leakage, high pressure is generated in the cooling system, causing the cooling agent to be lost, thus lacking heat in the cabin.
Can a warped/ deformed cylinder head be repaired?
Yes, you can repair a warped cylinder head, it can be corrected and the old cylinder head gasket replaced, but not everyone can do these repairs properly and it will cost you quite a lot.
To avoid these repairs, if you have the engine modified for increased performance, then it is best to increase the cooling system performance as well because the car manufacturer thinks the power of the car based on the engine performance, makes some calculations regarding the heat released when burning the fuel and depending on the heat released, it calculates the cooling system, the lubrication system, the braking system.
Depending on the car weight, it is established what braking system the car needs, what tires to put on and so on. Therefore, the car manufacturer, depending on the performance of the car, thinks about the other car parts. That is why when you want to increase the engine performance you must also think of other parts that support these performances, especially engine cooling.
For those who do not have a modified car but drive the car more aggressively, the first thing you have to do is equip cars with a quality coolant that will have a high boiling point. However, even if it respects the cooling qualities, the coolant can cause problems, if they do not comply with the manufacturer’s rules.
And, to make it even more complicated, very few antifreeze producers have rules.
Cause of cylinder head warping
Technically, the temperature sensors in the engine are not fixed in the engine. The hottest point in the engine is just near the combustion chamber. In this combustion chamber, when the explosion occurs, the flame has a very high temperature, for very short periods, of 2000 degrees Celsius (3632 F), and the metal components around the combustion chamber will heat very much.
So, near the combustion chamber, the components are very, very hot, with temperatures somewhere around 300 – 400 degrees Celsius (572 752 F), the engine oil cools the moving components, it has a very important role to lubricate, cool and clean.
Here is the secret. When the coolant travels those very hot spots, it has to do the heat transfer very quickly. What does this mean? If you put a coolant that has a boiling point at 110 degrees Celsius (230 F) and not at a higher temperature, let’s say 140-150 degrees Celsius (284 – 302 F) as needed, when it is close to the combustion chamber, where I said it was the hottest point, then the coolant will evaporate, and if it evaporates in that area then it practically does not cool enough and the engine will remain hot.
If the engine stays hot and you continue to drive very aggressively, then the engine temperature will increase to reach the point where the cylinder will deform.
Many drivers only look at the freezing point when buying a coolant, ignoring the boiling point which is also very important. But even most coolant producers do not specify the boiling point.
And for coolant car manufacturers specify certain rules that are ignored by drivers.
Failure to comply with the manufacturer’s specifications for engine maintenance is the main reason for the cylinder head failure.
The cylinder head may suffer bending problems due to the extraordinary pressure that is developed inside the combustion chamber but also due to extreme temperature changes.
This means that it no longer offers a flat surface to keep the cylinder head gasket in the correct position, which can later lead to costly problems, in the form of major repairs or total engine replacement. Bending or warping is a common problem for the aluminum cylinder heads.
Deformed cylinder head repair
If an engine is overheated, the cylinder head may become warped, in this case, it is necessary to plan the cylinder head surface in order to restore it and to create the perfect sealing.
In modern engines, the roughness of the flat surface of the cylinder head should be 10 microns, since most use a sheet cylinder head gasket, called the M.L.S. Because the M.L.S sealing material is inert, any malfunction of the cylinder head surface finish can lead to cylinder head gasket failure.
The machine used is an AZ SPA R330 / Chevallier FSG 1240 plane grinding machine, which corrects the cylinder head plane with a precision of 1 micron, the flat surface of the cylinder head is guaranteed.
Once the cylinder head has been rectified plan, it is necessary to adjust the valve seats to comply with the quotas imposed by the manufacturer, namely the elevation or deepening of the valves to the plane of the cylinder head.