Where to look at the engine number on a VAZ-2104 (“Boomer”): photo, transcript and authenticity check

Owners of AvtoVAZ classics - especially models VAZ-2104 (popularly known as “Boomer”) - sooner or later they are faced with the need to find out the engine number. This information is required to register with the traffic police, purchase spare parts, check the car's history, or even when restoring it after theft. But where exactly to look for this marking on the cylinder block? And how to distinguish the original number from the interrupted one?

Unlike modern cars, where the engine number is often duplicated in electronic systems, VAZ-2104 it is knocked out exclusively mechanically - on the metal of the block. However, the location may vary depending on the year of manufacture and modification of the engine. In this article, we will analyze all the possible places where the number can be applied, learn how to read it correctly and check for authenticity, and also tell you what mistakes are most often made when searching.

Where is the engine number on the VAZ-2104 (“Boomer”)

On all modifications VAZ-2104 The engine number is stamped on cylinder block plane on the right side (in the direction of travel of the car). The exact location depends on the type of motor:

• 🔧 Carburetor engines (2103, 2106, 21067): the number is located on top shelf of the unit, next to the thermostat. To see it, just open the hood and clean the surface of dirt.
• 🔧 Injection engines (2104-20, 21067-20): the marking has been moved a little lower - to area under the block head, closer to the oil filter. A mirror or flashlight may be needed here.
• 🔧 Engines with hydraulic compensators (2104-30): number stamped on side wall of the block, with the starter mounting point.

Important: on some copies (especially after 2000), the number may be duplicated on metal plate, riveted to the block. However, such a plate is not an official confirmation - the main one remains the embossed marking.

How to correctly read the VAZ-2104 engine number

Engine number on VAZ-2104 consists of two parts:

1. Prefix (3–4 characters) - indicates the engine model (for example, 2106 or 2104).
2. Main number (7 digits) — unique identifier of a specific motor.

Example of a full number: 2106 1234567, where:

• 2106 - engine model,
• 1234567 - serial number.

Please note: between the prefix and the main number there may be asterisk (*) or space - that's normal. The main thing is that the characters are clear, without any traces of interruption.

What to do if the number is erased or unreadable?

If the characters are blurry, try:

1. Light the surface at an angle (use a flashlight or phone light).

2. Take a photo of the number at close range and enlarge the image on the computer.

3. Apply the “imprint” method: attach a sheet of paper to the number and run a soft pencil over it - the raised symbols will be imprinted.

If the number is completely erased, an examination will be required at the traffic police or at a service station with equipment to restore the marking.

Decoding the VAZ-2104 engine number

The first digits of the number (prefix) indicate engine modification. Here are the main options for VAZ-2104:

Prefix	Engine model	Type	Volume (l)	Years of manufacture
2103	VAZ-2103	Carburetor	1.5	1984–2004
2104	VAZ-2104 (basic)	Carburetor	1.5	1984–2012
2106	VAZ-2106	Carburetor	1.6	1984–2006
21067	VAZ-21067	Injector/carburetor	1.6	1994–2012
2104-20	VAZ-2104 (injector)	Injector	1.5	2004–2012

Latest 7 digits - This is a serial number that is assigned at the factory. It does not contain additional information, but must match the data in the PTS and STS. If there are no discrepancies, the engine is not listed as stolen or damaged.

How to check the engine number for authenticity

Re-plating is a common problem in the secondary market. To avoid buying a “problematic” car, pay attention to the following signs:

⚠️ Attention: If the number is knocked out unevenly, the characters have different depths or the font differs from the factory one, this is a clear sign of interruption. You should also be wary if traces of grinding or welding are visible around the number.

• 🔍 Font depth: Factory symbols are stamped to the same depth (about 0.5 mm). Broken numbers are often flatter.
• 🔍 Tool marks: when re-beating, micro-scratches from a chisel or drill remain. Examine the surface under a magnifying glass.
• 🔍 Compliance with documents: check the number with the data in the PTS, STS and diagnostic card. Discrepancies are a reason for checking through the traffic police.
• 🔍 Number location: If it is not in the standard location (see section above), this may indicate a replacement unit.

To be completely sure, order examination of license plate units at an accredited center. The cost of the service is from 1,500 to 3,000 rubles, but it will save you from buying a stolen or damaged car.

Inspect the room on the block in daylight|

Check with data in PTS and STS |

Check car history through services (Autocode, traffic police)|

Pay attention to traces of interruptions (uneven font, scratches)|

If in doubt, order an examination -->

Common mistakes when searching for engine numbers

Even experienced car owners sometimes confuse the engine number with other markings. Here are the most common mistakes:

1. Confused with body number: body number on VAZ-2104 stamped on radiator top cross member (under the hood) or on trunk floor. It is longer (17 characters) and starts with letters XTA.
2. Look for the number on the block head: applied to the cylinder head only manufacturer's marking, but not the engine serial number.
3. Ignore duplicate sign: on some engines (after 2000), the number is duplicated on a metal plate. However, it does not replace the main knockout!
4. Doesn't clean the surface: Dirt, oil or rust may obscure the symbols. Always wash the unit before inspection.

⚠️ Attention: If the seller refuses to provide access to inspect the engine number (for example, citing “difficult access”), this is a reason to doubt the integrity of the transaction. On VAZ-2104 The number is always visible without disassembling the engine!

How to restore the engine number if it has been erased

If the number has been erased by time or corrosion, it can be restored in several ways:

• 🛠️ Chemical etching: specialists apply a reagent that reveals hidden symbols. The method works if the number is not interrupted.
• 🛠️ Ultrasonic cleaning: Removes oxides and reveals the original knockout.
• 🛠️ Magnetic flaw detection: Used to identify traces of crossover under a layer of paint.

It is not recommended to restore the number yourself - this may damage the block or distort the characters. Contact certified centers that provide examination report for the traffic police.

Cost of number restoration in 2026:

• Simple manifestation (without examination) - from 800 rubles.
• Full examination with a report for the traffic police - 2,500–5,000 rubles.

FAQ: Frequently asked questions about the VAZ-2104 engine number

Is it possible to drive if the engine number does not match the title?

No. The discrepancy between the engine number and the documents is equivalent to change in vehicle design (Article 12.5 of the Administrative Code). The fine is up to 500 rubles, but the main problem is that such a car will not pass inspection and will not receive a diagnostic card. To legitimize a discrepancy, you need to:

1. Pass an examination at NIIAT or an accredited center.
2. Obtain an opinion on the safety of the change.
3. Re-register the car with the traffic police.

The procedure will take 1–2 months and cost 5,000–10,000 rubles.

What to do if the engine number is changed?

If you find signs of interruption, proceed as follows:

1. Refuse to buy a car (if we are talking about a deal).
2. If the car is already yours, contact the traffic police with an application for a theft check.
3. Order a forensic examination (cost - from 3,000 rubles).

A broken number is the basis for seizing a vehicle and initiating a criminal case under Art. 326 of the Criminal Code of the Russian Federation (“Falsification of license plates”).

Where else can I find the engine number other than the block?

On VAZ-2104 The engine number is duplicated only in documents:

• PTS (item “Engine”),
• STS (column “Engine No.”),
• Diagnostic card (if you have undergone technical inspection).

There is a duplicate plate on the motor itself no (except for rare copies after 2000). If the seller shows the number on the “additional tag”, this is a reason to doubt the authenticity.

Is it possible to find out the year of manufacture by the engine number?

No, The engine number does not contain information about the year of manufacture. It only indicates the motor model and its serial number. The year of manufacture of the car is determined by:

• Body number (first 3 characters after XTA).
• Data in the PTS (column “Year of issue”).
• A plate on the body (under the hood or in the driver's door opening).

What happens if you do not indicate the engine number when registering with the traffic police?

From 2020 engine number optional for vehicle registration (Order of the Ministry of Internal Affairs No. 605). However:

• If the number is on the PTS but not indicated on the application, the inspector may require an explanation.
• When selling a car, the new owner may encounter problems if the number does not match the documents.
• To pass the technical inspection, the engine number is checked for compliance with the vehicle title.

We recommend that you always indicate the engine number when registering to avoid problems in the future.