The ZMZ 402 engine was developed and produced for installation in cars.
Peculiarities. The engine itself is a slightly modified GAZ-24D engine. The modernization affected the cylinder head, oil pump, and exhaust manifold. The engine has a different camshaft with increased valve lift by 0.5 mm (9.5 mm instead of 9.0 mm). The 402 engine has an archaic design from the 50s. The engine has a lower camshaft, which pushes the valves through rocker arms using duralumin rods. Instead of a rear crankshaft oil seal, a packing is used, which becomes a common cause of oil loss due to the design features and poor quality of engine assembly.
In general, the ZMZ 402 is a simple and reliable motor by the standards of the 70s and even 80s. It is easy to maintain, unpretentious, easily digests not the best fuel and has great maintainability. Throughout its life (until 2006), the engine has undergone a variety of changes and there are several versions of its design (see below).
The service life of the ZMZ 402 engine cannot be called impressive, but it cannot be called short either. If you do everything correctly and on time, do not turn the engine to high speeds, monitor oil leaks and fix them in time, then the engine can easily take care of 250 thousand km or more. The ZMZ 402 was replaced by a new engine - more powerful and economical.

Characteristics of the ZMZ 402 Volga, GAZelle engine

Design

Four-stroke four-cylinder gasoline carburetor with a contact ignition distributor, with an in-line arrangement of cylinders and pistons rotating one common crankshaft, with a lower camshaft. The engine has a closed-type liquid cooling system with forced circulation. Lubrication system - under pressure and splashing.
Aluminum cylinder block with wet cast iron liners. Aluminum pistons. Eight-valve cylinder head, cast aluminum. The valves are equipped with a single spring and are actuated via rocker arms.

Modifications

ZMZ 402.10 is the most popular engine with a compression ratio of 8.2, uses 92-octane gasoline. Used for installation on all Volga cars (GAZ-24, GAZ-2410, GAZ-3102, GAZ-31029, GAZ-3110 of early releases);
ZMZ 4021.10 - option with a reduced compression ratio to 6.7, for 76 gasoline;
ZMZ 4022.10 - prechamber engine. The motor is very rare, has a lot of differences and, in fact, is experimental, therefore, in 1992, the production of prechamber engines was discontinued due to the high cost of production and unsatisfactory performance;
ZMZ 4025.10 - intended for cars of the Gazelle family (same 4021.10);
ZMZ 4026.10 - intended for cars of the Gazelle family (same 402.10).

Service

Changing the oil in the ZMZ 402 engine The oil is changed every 10 thousand km. Engine oil volume is 6 liters. When replacing along with the oil filter, you will need about 5.8 liters. The oil is suitable for SAE 5W-30, 5W-40, 10W-30, 10W-40, 15W-40 (many car owners recommend using semi-synthetic oil, and the use of liquid oils and synthetics leads to unnecessary leaks).
Adjustment of valves It is necessary to adjust the gaps every 15 thousand km. For exhaust valves, the normal thermal gap is in the range of 0.4 - 0.45 mm. For the intake valves of the first and fourth cylinders - 0.35 - 0.4 mm. The valve clearance of the second and third cylinders is 0.4 - 0.45 mm.

ZMZ-402- a family of gasoline 4-cylinder automobile engines produced by JSC Zavolzhsky Motor Plant. A modernized version of the ZMZ-24, which in turn was created on the basis of the ZMZ-21.

This family of engines was used on cars of the Gorky Automobile Plant, such as: Volga-2410, Volga-3102, -31029, Volga-3110 and GAZelle.

Liquid-cooled four-cylinder in-line engine with electronic ignition (uses commutator). An interesting feature is the presence of an oil cooler.

The base engine of the ZMZ-402.10 family in the factory configuration used gasoline with an octane number of 92, but the variants for taxis (ZMZ-4021.10) and Gazelles were designed for fuel with an octane number of 80 (76 according to the motor method for determining the octane number).

The design is largely archaic and has not undergone major changes since the 50s. A rocker-rod timing belt with a lower camshaft (OHV) is used, a scheme that was considered obsolete even in the USSR already in the 70s due to the high mass of timing parts, leading to the unattainability of high speeds.

The advantage of the engine was that it was simple in design and maintenance, unpretentious, and capable of withstanding such overloads, from which, sometimes, another engine would quickly fail (overheating, operation under increased load, etc.). The simplicity of the device made it possible to carry out complex, but not major, engine repairs in an ordinary workshop, of course, provided that all the requirements of the manufacturer were met. The reliability of the engine, combined with its simplicity, have become the prerequisites for the fact that, despite the fact that it was developed many years ago, it is still in operation today. In addition to its advantages, the engine also had disadvantages. One of these is known to every car enthusiast who has ever operated a car with such an engine - this is the rear crankshaft oil seal, which is a regular packing (rope impregnated with graphite special lubricant). If the engine was operated in a gentle mode, and its speed did not exceed 2000 - 2500 per minute, then the packing more or less withstood, but when operating above 3000 rpm, it quickly lost its properties, and the engine began to expel oil. Another problem was the imperfection of the geometric configuration of the gas pipelines from the carburetor to the cylinder head. As a result, when the carburetor throttle valve was closed, an uneven amount of mixture was supplied to the cylinders and the engine jerked at idle. Car enthusiasts tried to keep such twitching to a minimum: those who were most responsible for this usually maintained the required valve clearance at a constant level, changed the spark plugs to more modern and reliable ones, and also replaced the switch and ignition coil - components from engines of cars of the VAZ family were usually used "

The ZMZ-402.10 family includes carburetor, gasoline engines with in-line cylinders and an aluminum block.

To reduce environmental pollution, the engines are equipped with an exhaust gas recirculation system (EGR).

The ZMZ-402.10 and ZMZ-4021.10 engines are designed for installation in middle-class Volga-type passenger cars, minibuses, and off-road vehicles manufactured by the Ulyanovsk Automobile Plant.

The ZMZ-4025.10 and ZMZ-4026.10 engines are designed for installation on light-duty Gazelle-type trucks and minibuses.

The designation ZMZ-402 hides a whole line of power units produced by the Zavolzhsky Motor Plant. These 4-cylinder gasoline engines are installed primarily in Gazelle and Volga passenger cars. You can find information about their use on Latvia minibuses and some models of the Ulyanovsk Automobile Plant.

History of engine development

The 402 engine began to be installed in cars in 1958. At that time it had a different designation - ZMZ-21A and ZMZ-24D, but it was still the same engine. The prototype was an even earlier modification, which the designers worked on in 1954-1955. Then it was a completely new engine option for the GAZ-56 car, which did not even leave the assembly line. The 402nd unit began to be called only in 1980.

The main representatives of the 402 line are:

• ZMZ-402.10 as the main basic option for AI-92 gasoline.
• ZMZ-4021.10, consuming A-76 fuel.
• ZMZ-4022.10, which has a new type of ignition, the so-called pre-chamber-torch.

During the operation of 402.10 engines, they often tried to use cheaper fuel. To do this, the car owners converted the engine to run on gasoline with a lower octane number. As for the flagship of the 402 line - ZMZ-4022.10, there are opinions that the idea of ​​\u200b\u200bprechamber-torch ignition was taken from Honda's Japanese colleagues.

Since 1996, a younger and more modern brother of the 402 appeared - ZMZ-406. For some time, both lines were installed on cars of the Gorky Automobile Plant. Nowadays the 402 engine can only be found in spare parts.

Description and technical specifications

ZMZ 402 series engines are unpretentious in operation and quite easy to maintain. Gasoline engines with a carburetor have 4 cylinders arranged in a row. They were installed mainly on GAZ cars: Volga and Gazelle.

The working volume of the power unit is 2.445 liters, which allows it to develop a power of 100 hp. With. or 73.5 kW. The compression ratio is 8.2 - this allows the use of AI-92 gasoline. The cylinder diameter and piston stroke are 92 mm. The total weight of the unit is 181 kg. The exhaust system includes exhaust gas recirculation, which significantly reduces environmental pollution and allows you to comply with regulations.

Components

The 402 engine cylinder block and upper crankcase are one piece and made of high-strength aluminum alloy. Cast iron cylinders are represented by removable liners. To fasten the block head on the upper surface, 10 “lugs” are provided. At the bottom, the engine block is divided into 4 parts by partitions. They house the crankshaft main bearings.

Each cast iron bearing cap is secured to the block using two 12mm studs. Since the block is bored together with the covers, they cannot be swapped. Therefore, for convenience, they are assigned numbers stamped on all except the 1st and 5th.

A timing cover made of aluminum alloy is attached to the front of the block. And to the rear is the clutch housing. All connections are tightened with fastening bolts through paronite gaskets. The 402 engine has an aluminum head common to 4 cylinders. Fastening to the block is done with ten 12 mm studs. The cylinder head gasket is made of asbestos coated with graphite and surrounded by a reinforced frame. Its minimum thickness is 1.5 mm.

Modifications 402.10 and 4021.10 have block heads of different thicknesses. This is due to the different volumes of the combustion chambers. Essentially, the 402.10 head is made by milling the bottom edge of the 4021.10 head by 3.6mm.

During maintenance, special attention is paid to the car engine. After 20 thousand km, it is recommended to stretch the head, as well as adjust the valve clearances.

Maintenance

In order for the 402 engine, whether it is a Gazelle or a Volga, to work long and efficiently, it is necessary to carry out timely maintenance. The engine, as you can already see, does not have complex electronic components and does not require highly qualified maintenance. What points should you pay special attention to?

Tuning 402 engine

Considering the age of the engine and modern increased needs, one can understand why many craftsmen are trying to improve the engine. "Volga-402" is a fairly old modification, I would like to update it. What can be done? More power is what the 402 engine needs. "Gazelle" and "Volga" will benefit significantly from this. There are several options for such tuning.

One of them is boring the block for larger diameter sleeves. If the original 402 block has sleeves 92 mm in diameter, then the bored one has all 100 mm, just like on the modern UMZ-4216. In this case, new sleeves are also installed in 100 mm size. The main disadvantage of such an upgrade is the deterioration of the thermal conditions of the cylinder block. After all, the walls became thinner by the size of the groove. And this is as much as 4 mm.

In another embodiment, the increase in power is ensured by grinding the block head. At the same time, the compression ratio increases, which allows you to switch to gasoline with a higher octane number. You can also increase the diameter of the exhaust pipe and slightly widen the exhaust manifold. All this will give the necessary plus 5-10 liters. With.

The most noticeable increase in power is up to plus 30 hp. With. - is replacing the carburetor with an injector. True, this is a rather troublesome and expensive procedure.

Other ways to increase power

Simpler, but no less effective options would be:

• flywheel groove;
• replacing the standard piston with a lightweight one;
• increasing valve diameters;
• replacing the standard K-151 carburetor with more modern analogues;
• new tuning camshaft;
• installation of more expensive and high-quality spark plugs from a foreign car with replacement of high-voltage wires;
• use only synthetic or semi-synthetic oil in the lubrication system;
• reconfiguration of the exhaust system.

To summarize, it can be noted that the ZMZ-402 engine increases its power in various ways. However, a car with such an engine will never be a racing car. This is, first of all, a reliable and high-torque unit for workhorses.

Possible faults

Let's consider possible options for the main problems of the GAZ-402, the engine of which is no longer new and has problems.

1. Doesn't start. There can be many reasons for this. The main ones are problems with the carburetor and fuel system.
2. Unstable revs, poor idle. Again, the problem is most likely in the carburetor or incorrect valve clearances.
3. Engine overheating. Here the focus is on the water cooling system. These are the thermostat, water pump and radiator.
4. Oil consumption. In this case, the seals are checked first, and then the oil rings and valve seals.
5. Engine knock. Most often, this reason can only be eliminated by a thorough engine repair.

Repair of 402 engine

With any operation, the 402 engine begins to fail sooner or later. You shouldn't be afraid of this. There are no eternal mechanisms, but there are good specialists and a wide range of spare parts. In this case, it is not necessary to wait for knocks that are unnatural for the unit. The indication for repair is a simple increase in oil and fuel consumption. In the GAZ-3110, the 402 engine, for example, should have a gasoline consumption in the city of about 13.8 liters per 100 km. The ZMZ-402 engine is quite easy to operate in the summer. When preparing it for winter, you should first check all technical fluids. These are engine oil, coolant, brake fluid and windshield washer fluid. The oil should be changed to semi- or full synthetic. Pour antifreeze into the cooling system at the required freezing point.

The weak link of winter driving is the carburetor. It needs to be configured in a certain way. The adjustment is made on a hot engine. The idle speed is set with a special screw. After tuning, it is important to practice the operation of opening and closing the carburetor choke.

Finally

The 402 engine is a high-quality product of the Zavolzhsky Motor Plant. More than half a century has passed, and it still continues to delight some car owners. Ease of operation, a large selection of components and inexpensive maintenance have determined the popularity of the unit for many years.

The GAZ 24 passenger car was developed in the mid-60s of the twentieth century, and in July 1970 it completely replaced its predecessor. Accordingly, a completely different internal combustion engine was created for the new Volga, which was assembled at the Zavolzhsky Motor Plant.

Classic car GAZ 24

The ZMZ 24D and ZMZ 2401 served as the prototype of the internal combustion engines (ICE). The new engine was fundamentally similar to the power unit of the twenty-first Volga and even looked similar to it. But the engine parts were almost all different, and for the most part were not interchangeable with each other.

general description

ZMZ 24D - 8-valve four-stroke four-cylinder engine, had an overhead valve arrangement and a lower camshaft arrangement. The cylinder block and cylinder head (cylinder head) were cast from aluminum alloy AL 4. The internal combustion engine was designed to run on AI-93 gasoline fuel. The ZMZ 2401 motor had the same characteristics. Unlike ZMZ 24D, ZMZ 2401 ran on A-76 gasoline. The fuel system was equipped with a two-chamber K 126G carburetor.

ZMZ-24D engine diagram

At one time, the use of an aluminum cylinder block (BC) and cylinder head was an innovation and was considered an advanced technology. “Twenty-four” engines existed without any changes until 1985, when they were replaced by a new generation of engines ZMZ 402 and ZMZ 4021.

The Zavolzhsky Motor Plant continued to produce the ZMZ 24D and ZMZ 2401, but as a spare unit. New ones and their modifications since 1987 were equipped only with new engines.

Technical characteristics of ZMZ 24D and ZMZ 2401

The twenty-fourth series engines had the following characteristics:

From 5 to 5.5 liters of engine oil were poured into the engine oil sump (according to various sources), but according to verified data, five and a half liters were required to reach the full level on the oil dipstick.

The ZMZ 24D and ZMZ 2401 motors had only two differences between themselves - the cylinder head itself and the pusher rods. The ZMZ 2401 block head had a larger cylinder combustion chamber due to thickening of the metal in this area. The height of the cylinder head of the ZMZ 2401 is 98 mm, while for the ZMZ 24D this parameter is 94 mm. The cylinder head was distinguished by measuring the height with a caliper; experienced mechanics determined the differences by eye. The rods differed in length; in the internal combustion engine version for 76 gasoline they were 4 mm longer.

An example of a ZMZ 24D engine for 76 gasoline

ZMZ 402 and ZMZ 4021

In 1985, serious modernization of the Twenty-Four began. The changes concerned the interior, body, . They also touched the engine. What’s most interesting is that the internal “filling” of the engine has not changed at all, and the engine volume remains the same. Why then was all this modernization started?

Thanks to innovations, internal combustion engines have become more convenient to maintain and repair. Then, albeit slightly, the engine power increased. According to the design ideas, the engine life should have increased.

New internal combustion engines have the numbers 10 in the designation, that is, the engines have the indices ZMZ 402.10 and ZMZ 4021.10. But for simplicity, we will not write down the full name.

The difference between the ZMZ 402 and the ZMZ 24 engines

This is what the ZMZ 402 engine looks like

The following differences exist between the two types of engines:

Prechamber engine ZMZ 4022.10

In 1981, the Zavolzhsky Automobile Plant, in order to increase the power of the power unit, created a new experimental engine, which turned out to be transitional between ZMZ 24 and ZMZ 402. The engine was conceived for, but it was also installed by an experimental batch on “twenty-fours”. In particular, such cars were used in taxis.

This is what the new Volga Gas 3102 looks like

The ZMZ 4022.10 cylinder block is almost indistinguishable from the 402nd engine outwardly, but was completely different inside. All the differences were in the fit of the cylinders and in the liners themselves.

Unlike the easily removable liners of engines 24 and 402, which were sealed with the block through a copper gasket, the liners in the prechamber engine block were fixed with two rubber rings. They “sat” in the seat so rigidly that sometimes it is impossible to remove them even with a puller. By the way, such blocks were called “chill blocks”.

The block head had its own special design. A small combustion chamber and one small valve were added to each cylinder. The principle was that the combustible mixture is first ignited in this chamber (prechamber). Then, due to the “explosion,” the ignition of the main mixture increases, which helps to increase the power of the internal combustion engine.
It should be noted that the rated power of this unit was stated to be 105 hp. on 93 gasoline, and the engine was indeed very playful and revvy.

It was possible to identify the prechamber engine on a car immediately by opening the hood. What made this engine stand out was the aluminum valve cover, which cannot be confused with the stamped steel 24 or 402 cover.

Accordingly, ZMZ 4022.10 had its own parts that were not interchangeable with any others:

• Combined intake and exhaust manifold;
• Carburetor;
• Rocker axis;
• Cylinder head;
• Prechamber valves;
• Valve lid;
• Manifold gasket.

This list does not include the cylinder block and piston liners. The fact is that the block and liners found their application in ZMZ 402 engines.

Installed motor ZMZ 402

The ZMZ 4022 motor turned out to be not a very successful idea. He was very capricious with the fuel system settings. Quite often the engines refused to start; we had to turn the starter for hours to revive the engine. The launch could have happened unexpectedly, and no one could understand what was going on. For this reason, after three years they decided to abandon such engines.

Chill blocks and piston groups from the ZMZ 4022.10 engine remained in ZMZ warehouses, and these parts were put into production. Therefore, periodically, when repairing the “four hundred and second” engine, it was discovered that a similar unit was installed on the engine. Externally, such a motor can be identified by the characteristic casting of the block, and not immediately, only with an experienced eye.

Those internal combustion engines that presented surprises with the launch were still “revived”, the method was elementary - they took the entire cylinder head assembly from the ZMZ 402 and rearranged it. True, this became possible only after the 402nd engine went into production.

Malfunctions inherent in motors of the ZMZ 24 series

A malfunction of almost any engine is increased oil consumption and crankshaft knocking. Another thing is that for some internal combustion engines this is a “disease”, while others are quite resilient in overloading and oil starvation. “Volgov” motors belong to the group of resistant and hardened ones, but there are still sores.

Characteristic features of 24 engines that are inherent in these particular models:

• Rear main bearing oil leak;
• Wear of the camshaft bed or bushings, as well as the shaft supports themselves;
• Breakage or rotation of the hex drive of the oil pump;
• Triggering of the teeth of the textolite camshaft gear;
• Wear of the brass connecting rod bushings for the piston pin.

An oil leak from the rear main bearing is familiar to almost every Volga driver.
The fact is that over time, a gap forms at the junction of the two halves of the stuffing box. The stuffing box “dries out” and contracts under the influence of temperature.

In addition, loose connections are created due to the drying out of two rubber seals (“boots” or “flags”). This disease can be treated by laying a good oil-resistant sealant at the joints of the seals. Of course, the padding and “flags” must be replaced. When the operation takes place in place (without removing the crankshaft), the top packing is not changed. And it’s almost impossible to get to it.

Replacing the rear main oil seal is useless if the piston group smokes and the engine consumes oil. Excessive pressure primarily “presses through” this connection. If the crankcase ventilation system is clogged, the oil will also first flow through the “rear main”.

Installing the rear main bearing

Once you clean the ventilation system, the rear oil seal stops leaking.

The rear oil seal may leak due to wear on the crankshaft journals. The wear of the journals is determined by listening to the engine. When you apply the gas sharply, a dull roar or knocking sound is heard in the area where the crankshaft is located. The knock is very characteristic, it is difficult to confuse it with something else. Replacing the oil seal will not help here; the shaft needs to be ground.

Camshaft bed

Apparently, not all differences between ZMZ 402 and ZMZ 24 were discussed in this article. ZMZ also modernized the cylinder block in the camshaft seat. On all early releases of the Volga GAZ 24, aluminum blocks had bushings for the camshaft. The problem is that operating an internal combustion engine with low oil pressure leads to premature wear of the camshaft bearings and the seat of these bearings.

Camshaft diagram of the ZMZ 402 engine

Replacing camshaft bushings is a troublesome task, but doable in a garage. ZMZ produced repair bushings that could be installed instead of worn ones; it was necessary to have a set of reamers and a lot of patience, time and accuracy. The shafts were successfully ground to the repair size, and no major problems were observed.

Everything got worse after the Zavolzhsky Motor Plant decided to abolish the bushings and decided to install the shafts directly in the body of the BC.

Such bushingless blocks began to be produced after 1985. Moreover, this occurred on both ZMZ 24 and ZMZ 402.

After some time, the plant completely abandoned bushings, which caused and still causes a lot of problems for Volga owners. In the event of such a malfunction, there are two options left - either have the cylinder head “put in” to a factory where there is a milling machine, or change the block to another cylinder block.

Hex Drive Oil Pump

On ZMZ 24 engines, the distributor drive is also the oil pump drive. The oil pump drive is a hexagon that drives the pump itself. Over time, the hexagon wears out and rotates in the pump body, and if you do not monitor the oil pressure, trouble can happen to the engine - the crankshaft will knock and a major overhaul will be required. Hexagon breaks occur if the oil in the sump freezes in winter. Therefore, you need to watch the oil pressure carefully.

Camshaft gear

The knocking noise of the gear indicates wear on its teeth. It can knock for quite a long time, but it is better not to delay replacing the part. If a tooth breaks on the road, the car will not start and will not be able to drive further. The car will have to be towed to the nearest auto repair shop.

Upper connecting rod bushings (for piston pin)

Under load, connecting rod bushings tend to wear out. This is typical for many motors with “floating” pins. A knock caused by worn bushings is not too dangerous if it has just begun to appear. But you shouldn’t delay repairs; as a result, the piston pin may burst. Then the consequences will be dire. The knock of worn bushings is similar to the knock of the timing gear, but differs in that it is clearly audible under load.

The history of the ZMZ 402 gasoline engine begins in 1968, when the Zavolzhsky plant produced its first sample. The 4-cylinder power plant, which became another follower of the ancient GAZ 21, constantly received improvements and was presented in several modifications used on the Gazelle, Volga, Latvia models and cars of the automobile plant in Ulyanovsk. The engines differed in compression ratio - from 6.7 to 8.2 atmospheres. The base unit with index 402.10 ran on 92-octane gasoline and was structurally not much different from domestic engines of the 50s. Data on the types of oil being poured and its types will be discussed below.

The 402nd motor is made of aluminum alloy, whose tightness is ensured by applying a special resin coating. The unit is unpretentious and easy to maintain, has high maintainability and is known for its endurance under constant overload conditions. All this is confirmed by almost 50 years of serial production. However, in addition to its undeniable advantages, the engine is not without equally important disadvantages: valve knocking (the clearances must be constantly adjusted), vibration, uneven supply of the mixture to the cylinders due to the ill-conceived design of the carburetor, malfunctions of the thermostat, as well as the most important problem, which is in the rear crankshaft oil seal. The oil seal is made of rope soaked in lubricant, and the latter quickly loses its properties when exceeding 2500 rpm. However, all these shortcomings are not critical, given the age of the engine. ZMZ-402 has the correct geometry, and its heavy piston system with a small stroke provides quite strong traction. For comparison, on the 402 engine the piston stroke is 92 mm, and on the Chrysler engine it is 100 mm.

The service life of the engine is from 200 thousand km or more, if you take care of it, correct all faults in a timely manner and fill only with oil recommended by the manufacturer.

Engine ZMZ 402.10 / 4021.10 / 4022.10 / 4025.10 / 4026.10 2.45 l. 90 and 100 hp

• What kind of engine oil is filled from the factory (original): Synthetic 5W30
• Oil types (by viscosity): 5W-30, 5W-40, 10W-30, 10W-40, 15W-40
• How many liters of oil in the engine (total volume): 6.0 l.
• Oil consumption per 1000 km: up to 100 ml.
• When to change oil: 5000-10000