How to do a complete engine overhaul with your own hands

Engine overhaul is a comprehensive restoration or replacement of the main components of the power unit with new ones. Such repairs are carried out when the operational and resource indicators of the power unit have depleted, that is, the entire engine is restored.

This procedure requires significant financial costs, and all work must be performed on specialized high-precision equipment in compliance with all necessary standards.

What is a major overhaul

Overhaul is a set of repair work related to the replacement of parts that cannot be repaired (mainly pistons, rings, gaskets) and the repair of parts that can be restored to factory condition. After the overhaul, the engine is restored to its power performance indicators (power, compression, noiselessness and smooth operation). Unlike routine or unscheduled repairs (for example, the washer fuse blows or the heated rear window 2107 does not work), a major repair involves repairing the entire engine, and not individual parts. Therefore, this type of work costs a lot, requires experience, time and, preferably, a warm, well-lit garage if the driver wants to make capital with his own hands.

Since the engine is the heart of the vehicle, its repair must be carried out in compliance with all rules and regulations, accuracy and skill.

A little about contract engines

Recently, capital has acquired a worthy alternative in the form of contract engines. But not everyone knows what it is. To be honest, just a few years ago I didn’t really understand what was going on. But everything changes, new knowledge and good friends appear who can give advice.

If you look at the problem of engine wear from the perspective of money, then a contract engine costs about the same or can cost a little less than capital. But remember that a contract power unit means a used engine, that is, a used one. When contacting dubious organizations, you may be offered an engine whose condition, to put it mildly, is not very good. Plus, problems may arise with the legality of purchasing a contract engine. After all, it will have to be registered again later.

That is, I believe that choosing a contract engine rather than a major overhaul is relevant only in a few cases:

the engine in your car can no longer be restored due to serious breakdowns and major damage to its integrity;
it is required to change the power unit as quickly as possible, and major repairs take a very long time;
It is difficult to find suitable parts to restore the motor.

And if you are suddenly offered a supposedly excellent contract engine, and at an attractive price, I strongly advise you to refuse. The same g16a Escudo from Suzuki cannot be cheap if it is in good condition.

I hope this material has given you food for thought, and also allowed you to take a full look at the problem of overhauling power plants in cars.

When to overhaul an engine

Both gasoline and diesel engines burn out their resource after completing their allotted service life in engine hours (if the engine has been running for 1 hour, this is 1 engine hour) or mileage in thousands of kilometers.

If the following signs appear, it is necessary to overhaul the internal combustion engine:

You have to add engine oil, it goes somewhere.
Mechanical damage to the engine (crack in the block).
Compression in the cylinders is below acceptable.
Constant smoke from the muffler is blue or bluish (dark gray) thick and in large quantities.
Knocks are heard (it could be the liner turning, etc.).
The car doesn't pull as well as before, especially when going uphill.
When checking the spark plugs, they are always dirty, with carbon deposits, and covered in oil.
Fuel consumption has become higher than before.
A lot of gases enter the crankcase.
Low oil pressure in the system.
The motor overheats under light loads.
The engine runs intermittently.

These reasons do not necessarily indicate the need for a major overhaul of the internal combustion engine. If there are many such signs and they are repeated, then it’s time to trade in the car or do it yourself.

Based on the signs, they determine what kind of repair the engine requires:

current or continuous repairs (repair or replacement of individual parts, for example, painting a bumper);
technical repairs according to the schedule (repair or replacement of worn parts that have exhausted their service life);
unscheduled repair of the internal combustion engine (this is when the service life has not yet expired, but for some reason the engine has broken down);
major or major repairs, or capital repairs are done both according to schedule after a given service life, and after the final breakdown.

Our verdict

What's the result? Replacing the engine is a simpler and cheaper, and sometimes the only technically possible way to solve the problem. But if the engine initially has a poor reputation, say, at a certain point scuffs appear on the cylinders or the crankshaft may break, then replacement in this case will only delay the occurrence of the problem.

And it’s okay if you are replacing an engine with a mileage of half a million kilometers for a much more recent one, which has “run” a hundred thousand. What if you exchange an awl for soap? A major overhaul will not save either time or money. In general, this is not a question about economic feasibility, but about further reliability and service life, since “capital” can breathe a second life into an old engine. But only on condition that the repairs are carried out at the proper level. No confidence in the performers? Then it’s better to immediately choose the replacement option!

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What is the engine mileage before major overhaul?

The mileage life of an average car is considered to be about 200 thousand km, after which its characteristics decrease and it’s time to invest in some capital. There are cars with a lifespan of 1 million km (million-dollar engines are called), although now there are rumors that the lifespan of new expensive cars, which used to be million-dollar, now have a much shorter lifespan. The more often a car is repaired, the more financially profitable it is for auto manufacturers and auto parts stores, but this spoils the reputation of a brand or a specific car model.

In some cases, with severe wear of the internal combustion engine or severe breakdowns, it is more advisable to do an engine swap.

The manufacturer AvtoVAZ has set the average mileage for VAZ 2114 cars = 150 thousand km. On average, all Russian cars have the same indicators. But, if various problems are corrected in a timely manner, the engine life can easily withstand 250 thousand km. The service life of foreign car engines is, on average, 200,000 - 300,000 km before overhaul.

High mileage is the main reason

For engines with very high mileage, a major engine overhaul may be required (suddenly), because... mechanical elements and internal seals wear out. It is difficult to determine how long it will take for your engine to require capital.

It all depends on how the car was maintained and operated. However, it can be assumed that a properly maintained drive unit will require repairs only after 350-400 thousand km. mileage

Of course, engine overhaul may be required much earlier, with much lower mileage. The reason will, naturally, be poor engine maintenance. Let's look at what could be the main reasons for engine failure ahead of schedule.

What is included in an engine overhaul?

Overhaul of diesel and gasoline engines is done in stages:

Disassembling the internal combustion engine.
Parts washing and cleaning.
After cleaning, an experienced auto mechanic is able to determine how badly certain parts are worn and whether they can be repaired or better replaced. They do troubleshooting, that is, after the cylinder head (cylinder head) has been removed, it and the cylinder block (cylinder head) are checked for chips and cracks; examine the cylinders for scuffs and scratches; determine the gaps of mating parts; inspect the condition of the pistons for the presence of chips, shells, carbon deposits; inspect the crankshaft connecting rods; study of the internal combustion engine crankshaft; fingers; bearings; parts of the gas distribution mechanism are also checked (valves, rocker arms, etc.). They also compare the dimensions of important parts with the factory ones.
After troubleshooting, it is necessary to assess the degree of wear of the entire engine: what to change, what to leave, what to repair.

Turbocharged engines

Modern small turbocharged power units, built according to downsizing principles, may require major overhauls much sooner than naturally aspirated units.

For such engines, long mileage is already about 200 thousand. kilometers. Lack of power reserve, “chips” of drives, high susceptibility to overheating, carbon formation and detonation. You will have to pay for all this sooner or later.

Tips for repairing internal combustion engines

If you have never had to completely disassemble an engine, then it would be more correct and better to invite a friend who understands it.
It is advisable to carry out disassembly in a warm and well-lit garage.
During disassembly, place all bolts, washers and nuts in a box with partitions, do not throw everything in one bucket.
During disassembly, remember the sequence if you are doing this for the first time.
If you don’t know what the spare parts are called, take the old parts to the store and show them to the seller.

Dismantling and disassembly

Depending on the make and model of the car (engine design, number of cylinders, type of gearbox), the engine removal process may vary. The engine location on front-wheel drive and rear-wheel drive is also different.

Carburetor engines are much easier and faster to disassemble, since they are not stuffed with electronic devices, in the presence of which, in order to get to the engine itself, you have to carefully dismantle them all.

So, if you have to capitalize Kamaz, for example, then its diesel engine from the Yaroslavl YaMZ-236 plant will take about 10 hours to dismantle. If you do the same work with heavy-duty Kamaz analogues, it will take more than 30 hours.

And to disassemble a VAZ engine, it takes about 3 hours. And the engines of foreign passenger cars will take about 10 hours.

It is necessary to disassemble slowly, throwing bolts and nuts anywhere. With disassembly, diagnostics, so to speak, have already begun.

Defects of elements during internal combustion engine capitalization

The defect in this case is mechanical, that is, it is necessary to check visually and with the help of measuring instruments the wear of parts.

Troubleshooting of internal combustion engines includes the following work:

inspect the crankshaft and measure its dimensions, check for bends and alignment;
inspect the cylinder block body (BC);
check the parts of the connecting rod and crank mechanism for play and the condition itself: pistons, cylinders, rings, pins, connecting rods;
inspect the cylinder head housing (cylinder head);
gas distribution mechanism parts;
determine the maintainability of parts and assemblies.

What spare parts are needed for engine overhaul?

After completing the troubleshooting procedure and sifting out those that are suitable for restoration and those that are not, you need to order new parts to replace the unusable ones. When you already know what spare parts are needed, you don’t need to delay ordering and purchasing them, since new parts still need to be prepared for installation.

Spare parts for overhauls for gasoline engines:

Liners (main and connecting rod).
Piston group parts.
Connecting rod pins.
Connecting rod bushings.
Valves (all, both intake and exhaust).
Oil scraper rings.
Gaskets (full set).
Valve guides and seats.
Pump with repair kit.
Oil filter and pump.
Other related details.

What spare parts are needed

Consider the list of spare parts for major repairs of the power unit:

Piston group kit, it includes pistons, piston rings, piston pin. If the block is sleeved or such a need arises, then sleeves are purchased accordingly. When purchasing a piston group, there is no need to rush; you must first take the block to where you are going to sharpen it, and only after measuring the master will tell you what type of repair the piston needs to be purchased.
It's a matter of desire; if you want, you can purchase pistons with recesses, especially useful if you are experimenting with split gears, etc. And the chain, despite its reliability, can break once every 20 years and then the meeting of the pistons with the valves is inevitable.
Main and connecting rod bearings are purchased after the crankshaft has been ground. After grinding the crankshaft, the master will tell you which bearings you need to buy - 0.25, 0.50, 0.75, 1. This depends on the degree of wear of the crankshaft. It is better to take original earbuds.
Oil pump. This matter is quite controversial, but I prefer to change it when conducting capital. Many people say that it can last for a very long time - I don’t take into account such stories, do it like that.
Camshaft I also recommend replacing it, but if finances are really bad, you can postpone replacing it, but this is not very advisable. Although if the camshaft is in good condition, you can leave it.
The intermediate shaft (drive shaft of auxiliary units, pig) is the shaft that rotates the distributor and the oil pump and is driven by a motor chain. This shaft greatly affects the pressure in the lubrication system - if the bushings are heavily worn, the oil pressure drops significantly. When overhauling an engine, the bushings must be replaced, processed with reamers, and the shaft is also either ground or replaced with a new one. There is also an intermediate shaft on ball bearings; this, in addition to increasing the service life of the industrial shaft, also allows you to increase the pressure in the lubrication system. From all this, it is necessary to take away that at the time of sending the block for grooving, you need to purchase a new one or take with you an old washer so that you can replace the bushings and grind the shaft (if you leave the old one), at least this is the case with us.
If the cylinder head is also being repaired, then it is necessary to purchase valves, valve seals, and springs (if the old ones do not hold the force).
I also recommend replacing the entire motor chain tensioning system, as well as the motor chain itself, this includes: crankshaft, camshaft, shaft sprockets, motor chain, motor chain tensioner shoe, motor chain tensioner, motor chain damper. Beware of fakes, there have been cases when the motor chain tensioner shoe was made of non-oil resistant rubber and it collapsed quite quickly. I try to install a plastic damper, since even if it breaks, it may not harm the engine as much as a rubber-metal one.
The crankshaft seals, rear and front, must be replaced.
You also need to purchase a set of gaskets, you can buy all paper gaskets separately, and buy them separately for the pan, valve cover and under the cylinder head.
Also check the bearing, which includes the gearbox input shaft, at the end of the crankshaft. If there is play in the bearing, it must be replaced.
If the engine knocks or the connecting rod bearing turns, then the connecting rod must be replaced.
Also, do not forget about all the consumables - oil, filter, coolant.

Grinding the block and crankshaft

After the issue with spare parts has been resolved, they begin to repair and restore the block and crankshaft of the internal combustion engine. Using a milling and surface grinding machine, the layer of the seat of the cylinder head and the block itself is removed until there are no shells or chips left. It happens that there are several deep shells, due to which you have to remove the layers in several passes. Usually, depending on the degree of damage, layers of 1 mm, 0.5 mm, 0.25 mm, 0.1 mm, 0.05 mm thick are cut off. After this, they begin to grind the surface to a mirror shine.

For crankshaft grinding, there is a special table that shows the thickness and efficiency values after repair compared to a new factory one.

Type of repair	Thickness, mm	Efficiency compared to new
Repair No. 1	0,25	80-90%
Repair No. 2	0,50	70-75%
Repair No. 3	0,75	65-70%
Repair No. 4	1,00	50-55%
Repair No. 5	1,25	40-45%
Repair No. 6	1,50	Less than 30%
Repair No. 7	2,00	Not applicable since 1995

Repair of the block head (cylinder head of the internal combustion engine)

Although it is not difficult to carry out repair work on the cylinder head, for some reason many people try to send it to a service center.

Repair of the block head consists of the following types of work:

We replace the camshaft (all that is in this engine).
We change the suction and exhaust valves.
We change the guide bushings.
We change valve stem seals and seats.
If there are cracks in the cylinder head, then we either change the head and grind it again, or weld these cracks with argon.

Assembly and installation of internal combustion engines

Sequence of engine assembly after major overhaul:

Install the half-shaft bearings and seat the crankshaft.
Install connecting rods and piston group parts.
Correctly install and tighten the yokes (arc-shaped crankshaft mounting).
Install the gaskets correctly, check that the gasket does not cover the channel holes.
Installation of covers covering the motor.
Install the oil pump and water pump.
Install the engine crankshaft pulley. We have already learned how to remove the crankshaft pulley.
Install the cylinder head.
Install the pan, crankcase.
Collect small knots.

If you decide to make a capital with your own hands for the first time, after all the work before assembly, it is better to carry out the assembly with an experienced specialist in this matter. The lifespan of the entire car depends on the quality of the assembly.

Conclusion:

Engine overhauls are very expensive. It is not surprising that in many cases it is easier to buy a used motor from a disassembly unit. However, it is always roulette. No one knows if the “new” engine will need major repairs in a few months.

Well, the best solution is to buy a well-proven reliable car and use it correctly, according to all the rules, without skimping on oils, filters, spark plugs, coolants, without suffering, in order to avoid a situation where engine overhaul exceeds the cost of the car, and a good 10 It becomes easier to scrap a summer car than to repair it.

Run-in after capital

The most enjoyable process in such work is the necessary running-in for the engine with new parts. During break-in, new parts are ground in, so it is not recommended to immediately apply a large load. It is recommended to run-in for up to 2000 km without jerks or sudden starts.

There are several break-in methods:

Running in cold on a stand.
Cold running without a stand. This method is common, especially in the CIS countries. After preparing everything necessary (engine oil and coolant are filled in), without starting the engine, tow the car at speed 3 for 2 hours. This method is not recommended. By the way, a very important reminder: motor oil has a code and symbols for additives; before purchasing it, it is advisable to learn how to decipher the markings of motor oils, after which you can make the right choice yourself.
Hot running. This method involves starting the engine and letting it idle for 3 minutes, then turning off the engine. And they do this several times, only waiting for the engine to cool down. Then, after short starts, start the engine and let it run for 1 hour. During break-in, the engine is inspected for leaks and other indicators. After running in, adjust the valve clearances and set the desired ignition. If contact ignition is installed, it is recommended to install electronic ignition instead of the old one. It reduces fuel consumption and generates high voltage up to 24 kilovolts, while contact ignition can supply no more than 18 kilovolts to the spark plug. Thanks to this, even dirty spark plugs produce a spark.
Natural run-in. It is run in under the following conditions: smooth ride, speed no more than 60 km. After overhaul without installing new liners, running-in is carried out up to 2 thousand km. If new liners were installed, then 4 thousand km.

Many people recommend breaking in only when cold, but some experts recommend breaking in both cold and hot.

Abroad, they say, car service centers have run-in and test benches for internal combustion engines. Using special electronics, this stand shows the service life of a restored engine.

If you decide not to do the overhaul yourself, but to send it to a service center, you will receive a guarantee for the repaired motor. The guarantee is given depending on how you choose, some for 20 thousand km, others for 30 thousand km. mileage

Tips and tricks

As already mentioned, the service life of an internal combustion engine before overhaul depends on many factors. In order to delay major engine repairs, it is necessary to pay special attention to the quality and correct selection of engine oil in relation to a specific type of engine, and promptly change the air, oil and fuel filters. Also, the power unit must be able to operate correctly, avoiding constant peak loads and tight driving. It is equally important to monitor the condition of the engine, quickly eliminate problems that arise, and carry out preventive procedures.

The main reason for rapid engine failure is oil changes, which are not carried out according to regulations. Increasing the replacement interval, taking into account the low quality of fuel and dusty roads in the CIS, leads to the fact that the engine ultimately runs on lubricant that has oxidized and lost its properties. Dust and deposits also enter the unit through clogged filters. As a result, the associated rubbing parts begin to work under conditions of increased wear, the channels of the lubrication system become coked, the power system suffers, etc.
Let us add that clogged filters can not only allow dirt into the engine, but also significantly affect the composition of the fuel-air mixture in modern engines with injectors. In this case, the quality of fuel atomization deteriorates, the power of the internal combustion engine decreases, and local overheating occurs. This also includes driving on low-quality fuel or with an inappropriate octane/cetane number, since detonation can quickly destroy a previously serviceable engine.
In order to avoid burnout or melting of pistons, burnout of valves and other troubles, you need to not only change filters and oil according to the regulations, but also fill in high-quality fuel, and also periodically clean the injector every 30-40 thousand km.
As for the oil itself, its viscosity changes with mileage, and the additive package stops working effectively after 10 thousand kilometers traveled. For this reason, any lubricant (even high-quality synthetics) when driving on domestic fuel should be changed no later than the indicated mark. It is also very important to select the correct engine oil, taking into account the vehicle manufacturer’s tolerances. Another problem is the large number of counterfeits on the modern fuel and lubricants market. Counterfeit motor oil does not contain a package of branded additives, and is also very often the cheapest “mineral oil”, which is bottled into containers for expensive synthetics or semi-synthetics of famous brands. The logical result is that deposits accumulate in the engine and parts wear out very quickly, especially on forced turbo engines. In some cases, rapid blockage of the lubrication system channels occurs, oil starvation occurs, and scoring occurs. A particularly dangerous outcome of driving on low-grade oil can be jamming of the power unit. Note that in such cases, many car enthusiasts rightly think about a contract engine, since the existing one may be in a state where its overhaul is impractical.
Another factor that affects the service life of the engine before overhaul is the proper operation of the internal combustion engine systems and mechanisms, as well as their correct settings. For example, problems with timing phases due to an incorrectly installed belt can lead to dire consequences over time. The appearance of engine tripping as a result of breakdowns of individual elements of the ignition system, incorrect adjustment of the said system (incorrectly set ignition timing), too “cold” or “hot” spark plugs can also be the reasons for the accelerated failure of the entire internal combustion engine. In order to avoid serious consequences, any changes in the operation of the motor should be a reason for its diagnosis in order to quickly eliminate the failure or malfunction that has occurred.
The appearance of extraneous sounds while the engine is running is also an alarming symptom. Knock of valves and hydraulic compensators, camshaft, crankshaft, connecting rod knock, knock of piston pins or pistons themselves, as well as other extraneous sounds are a sign that the car needs to be taken to a service center. Sometimes driving under your own power with a knocking engine is not recommended, and in some cases it is completely prohibited.
The temperature regime in which the power unit is operated also has a huge impact on the life of the motor. Overheating of the entire engine and local overheating can lead to deformation of the cylinder head, burnout of the cylinder head gasket, and failure of various parts and components. Cases where antifreeze gradually enters the engine oil are considered dangerous, diluting the lubricant and deteriorating the properties of the material. For this reason, it is necessary to constantly monitor the condition of the engine cooling system.