Block plane and broken gasket
Roughly processed plane of the engine block
“Punctured” cylinder head gasket on Niva and Shnivy is a birth defect. At some point they just went en masse. There is no need to be surprised. With modifications to the engine to meet new environmental standards, the designers are pushing the fan operating temperature further and further. This gives us an element of “glow” ignition. At a mileage of 15-25 thousand, the cylinder head gasket breaks, and so on down the list. Antifreeze to oil, oil to antifreeze. What do they do in the Papuan service? They buy a Fritex metal bag, install it, and 10 thousand later the client comes back with a new one, with the same question. Or rather, with two. How long? And the classic “what should I do?” It is not the Niva cylinder head gaskets or bolts that are to blame, it is the factory quality of processing of the block plane and the cylinder head plane that is to blame. Below I publish a photo of one of the blocks. I personally changed the gasket on it twice until I found the optimal set, which I now recommend. The metal bag does not help, but rather hinders. It cannot be crimped and does not fill uneven surfaces of the block. You need a shrink gasket that will completely accept the topography of the surface and the bolts that will constantly press it. This is the reason why hardened bolts are not rolled here. For a long time, the plant installed the Yaroslavl metal package “Fritex”, and now they have switched again to shrink gaskets. In a decent production facility, it would be easier to update the machine park and equipment, but at AvtoTAZ it turned out to be easier to go back ten steps along the road of technical progress.
Features of the camshaft on a NIVA car
At first glance, the camshaft of a NIVA car is very similar to any other camshaft, however, there are some points by which you can easily determine that this part is specifically for the NIVA.
- Most camshafts have a hex key (usually 27) between the cams of the second cylinder. The camshafts that are manufactured for the NIVA car have two hexagons on their axis (between the cams of the second and third cylinders). Visually, this is the main distinguishing feature of this part.
- The next differentiating factor is the distance between the base and the top of the cam. If you need to make sure that the part is specifically for NIVA, and the presence of a second hexagon does not guarantee the authenticity of the product, pick up a caliper and start measuring. The basic camshaft cam size is the same in most cases and is 30 millimeters. But the distance from the base to the top of the Niva is 37 millimeters. Measuring any other camshaft, the distance will be no more than 36.3 millimeters.
If both of these points are met, rest assured that the spare part is genuine and you can begin installing the camshaft on your Niva.
Technical features
Due to the increased size of the cams, as already described above, the intake phase increases. When compared with other cars, on a NIVA car this phase turns out to be 20 degrees higher (which is also indicated in the passport), this allows you to easily start even at idle.
Torsion bolts (plastically deformable)
cylinder head bolt of a new type
Part number: 21213-1003271-01-0. Name: Torx cylinder head bolt. This name (torsion bar bolts) is fundamentally incorrect, but what can you do if they are called that on all forums and in all stores. According to science, when they say torsion bar, they mean deformation from twisting. And in this case, tensile deformation. In stores, these bolts are also called cylinder head bolts for Niva Chevrolet or cylinder head bolts of a new type. I also came across the name torx or chamomile. These bolts, unlike hardened ones, provide a constant load. That is, in a very primitive way we can talk about the grommet effect, that is, about the constant force to compress the cylinder head gasket in the axial direction of the bolt. These bolts are widely used on imported engines because they avoid human factor errors. In fact, you don't need to tighten with the precision of a torque wrench. The final values are taken as angular values. I don’t really like this approach, but such things are now commonly called “assembly guarantee”.
Installing a new camshaft
If the camshaft is very worn, the valves are knocking and there is no way to adjust the clearance properly, then it's time to buy a new one! The cost of a new unit can range from 3,000 to 5,000 rubles.
After purchasing, do not rush to open the hood and change the spare part! The first step is to carefully examine the camshaft for defects or manufacturing defects. There should be no large burrs, burrs, excess or leaks of aluminum on it; the new shaft should rotate freely and easily by hand. Everything should look perfect, have a marketable appearance, because you are purchasing a new spare part, and it should last a long time and reliably, without any linings.
If, as a result of a visual inspection, something is suspicious to you, do not be afraid to return the part to the manufacturer and request a replacement. Ignoring a minor defect can lead to serious damage in the future.
Important tip
If the camshaft is replaced with a new one in a NIVA car, it will not be superfluous to replace the valve levers (rockers). This is done in order to avoid differences in the degree of production, which can affect premature wear of the entire mechanism.
Niva cylinder head bolts, installation
To work with bolts, a special tool is required. E16 head, which is not always included in universal tool kits, and a torque wrench. To make the process logically complete, the price list includes an E16 head (Sata or Force) and a torque wrench ( JTK) .
I won’t invent anything about the installation technology, just completely follow the factory manual.
- Submerge the bolts in a container of engine oil.
- Let it drain. Exposure for at least 30 minutes.
- Wrap and tighten according to the diagram.
Tightening force:
Stage 1 – tightening torque (12…20) N.m [(1.2…2.0) kgf.m];
Stage 2 – tightening with torque (50…70) N.m [(5.0…7.0) kgf.m];
Stage 3 – turning the bolts by 90-110 degrees;
Stage 4 – turning the bolts 90-110 degrees.
Tightening torque of bolt 11 (at the cylinder head tail): preliminary – (14…16) N.m [(1.4…1.6) kgf.m]; final – (32…40) N.m [(3.2…4.0) kgf.m].
How to properly tighten the head on a VAZ 2123
The cylinder head is tightened using a torque wrench. New bolts must be used, a new gasket must be used, and the surfaces must be cleaned. If necessary, the plane of the mating parts is restored.
The procedure for tightening the cylinder head is indicated in the following photo:
The tightening itself occurs in several stages:
- The bolts are tightened “by hand” without effort in the order shown in the photo.
- Bolts 1 to 10 must be tightened to Nm.
- Next, you need to wait a while and tighten the same bolts again with a torque of 70-85 Nm.
- Tighten bolt number 11 to 31-39 Nm.
- Bolts 1 to 10 must be turned 90 degrees. After waiting for some time, turn them again another 90 degrees. All this is done in the order shown in the photo.
Between doses it is necessary to pause for about five minutes. This allows the connection to get rid of unnecessary heat and allows the head to shrink correctly and tightly on the block.
When should you change the cylinder head gasket?
Such work will have to be done when the gasket is damaged. These could be cracks or holes in the gasket. If damaged, the car owner will observe the appearance of air in the cooling system . This will also be indicated by the bubbling of antifreeze.
Crack in the cylinder head gasket.
You will also need to change the gasket when there is not enough compression in the combustion chamber. In this case, the gasket may simply wear out and will no longer be able to perform its functions. Also, when cracks appear, antifreeze will enter the combustion chamber, which will lead to unstable engine operation.
How to disassemble a Chevrolet cylinder head
To find out why the cylinder head with which the Niva is equipped does not function properly, the said unit must be disassembled.
For this you will need:
- sets of spanner and socket wrenches, as well as a torque wrench;
- screwdriver set;
- sealant;
- coolant canister;
- fine-grained sandpaper.
Work on a Chevrolet is carried out in the following order:
- the car is placed on a ramp or pit (if you have just used the vehicle, then let the engine cool);
- do not forget to put the Niva on the handbrake and support it on both sides;
- disconnect the negative cable from the battery;
- drain the coolant from the radiator and the rest of the system;
- disconnect the drive levers from the valves and remove the hydraulic supports;
- remove the cable that drives the throttle valve from the holders;
- remove the camshaft along with the bearings;
- disconnect the hoses supplying lubricant to the Chevrolet hydraulic mounts;
- disconnect the connecting wires leading to the injectors, temperature sensors, throttle valve, idle speed and detonation;
- cut the plastic ties securing the mentioned Niva cables and move the latter;
- de-energize the spark plugs and, additionally, the temperature sensor;
- disconnect all pipes from the Chevrolet cylinder head - inlet and outlet, throttle, cooling system, adsorber, etc.;
- Only then turn off the fuel supply.
Which camshaft is better to install?
One way to avoid main engine noise is to replace them with adjusting bolts. In this case, it is also necessary to purchase a 213th camshaft, which can improve engine performance.
Problems with the shaft itself include:
- bearing wear;
- bullying in bed;
- cracks, fractures, axial deformation;
- seal damage.
Video 1, the shaft burst 2 times in a row.
Let's start disassembling (procedure)
- The first step is to remove the air filter. The four screws along the edges of the cover are unscrewed. The pipes are detached.
- The cable and the gas damper drive open.
- The valve cover must be cleaned of dirt; this is done in order to avoid clogging the engine from dust and debris accumulated under the cover.
- Next, you need to loosen the camshaft fastenings. It is important to secure the engine from accidental rotation; fixation can be done using any strong metal object clamped between the chain and the sprocket (for example, a screwdriver).
After completing all these steps, you can start replacing.
Tightening scheme
Using a large screwdriver, the chain tensioner is removed, then the camshaft gear is placed in its original place. The bolt and washer are tightened. The latter is controlled with pliers.
Next, the thermal clearance of the valves is adjusted. Assembly is carried out in reverse order.
Video 2: replacing the timing tensioner.
Source
Possible cylinder head malfunctions in a Chevrolet
Before talking about the nuances of tightening, it is necessary to talk in more detail about possible malfunctions of the Niva cylinder head.
So, if there is a drop in power, then you should suspect a poor connection between the air manifold and the head. To eliminate the above-mentioned breakdown, it is not at all necessary to disassemble the cylinder head. It’s another matter when the gasket lacks tightness - it can be caused by insufficient tightening of the bolts or wear of the seal. There will be a lot of fiddling around here. The symptoms of this problem depend on the nature of the gasket damage. So, if low compression is observed, then gases probably penetrate from one combustion chamber to another through a seal that has weakened in places.
Oil or coolant leaks (hereinafter referred to as coolant) indicate insufficient tightening or wear of the gasket in the area between the systems through which these compounds circulate. This problem also causes mutual contamination of the lubricant and antifreeze. The latter in Chevrolet noticeably changes color - it becomes brownish. The presence of such problems dictates the need for emergency repairs of the Niva.
