Check the motor before buying. How to check a diesel engine when buying a car. Acid deposits on the battery terminals

Buying a used car is a rather responsible procedure, as it involves a large number of legal and technical checks. As for the technique, that is, the analysis of the state of the vehicle, when buying a used car, maximum attention should be paid to the most expensive elements: body, engine, transmission, separate units of the chassis and steering.

If the condition of the body can be assessed visually, and the serviceability of the chassis can be easily checked on a lift and tested on the road, then the issue with the engine is not so easy to solve. As a rule, the seller will not allow the motor to be opened for diagnostics. Similar difficulties arise when it is necessary to check the removed engine at.

In this article, we intend to talk about how to check the condition of the engine when buying a car with gasoline, as well as what methods help to check when buying a car.

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We check the used engine before buying

To begin with, a lot about the state of the engine can be learned by visual inspection the engine itself and the engine compartment. First of all, you should remember that an outwardly clean engine that starts and runs does not mean that the engine is completely serviceable and in good condition.

Experienced craftsmen at the service station are well aware of this, and resellers of cars and not entirely honest sellers are also well aware of this. For this reason, when assessing the condition of a used one, you need to clearly know what to look for.

So, let's figure out how to check the engine when buying. First of all, even if you don't have much experience, you don't have to tell the car dealer about it. Try to refrain from any unnecessary comments, while step by step follow the instructions that we will describe below.

• Before inspecting your engine, start with simple questions about car and engine repair and maintenance. Ask what and when was done on the engine, on what mileage was the last time it was produced or, antifreeze, spark plugs, etc.
• Also inquire about the type and brand of the filled oil (for example, 5W30 or 10W40) and others technical fluids... In parallel, observe the clarity and transparency of the answers and the owner's reaction.

This approach will immediately allow you to identify either a reseller who does not know the history of the car, or a careless owner who did not pay proper and timely attention to the car.

Visual inspection of the motor

Then you can proceed to inspect the engine. If the seller prohibits or deliberately complicates access to individual external elements under the hood, then it is better to immediately refuse to buy such a car. If there are no problems, you can continue.

As we said, the first thing to look out for are traces engine oil... Oil drips or traces of antifreeze will indicate leaks through gaskets, seals, and other seals. In some cases, such problems can then be eliminated without serious financial investment, while in others, oil can be squeezed out as a result of serious engine malfunctions.

It turns out that a worn gasket or an oil seal can leak, which is not so difficult to change. However, in some cases, similar leaks can occur for other reasons. For example, when the engine was overheated, it can then "lead", that is, the geometry of the mating plane is violated. As a result, the problem cannot be solved by replacing the gasket.

We add that even if nothing serious has happened to the engine, a dirty ICE with leaks will indicate that the owner for some reason does not pay due attention to the condition of the vehicle, carelessly operates the car, etc. This suggests that the regulations for passing maintenance, changing oil and consumables could be systematically violated, which is very bad for.

• in order to give a general presentation of the car;
• for concealing oil and technical fluids drips;

Unfortunately, the second case is much more common, since a serviceable motor is rarely washed before being sold. Moreover, sellers separately draw the attention of the buyer to the fact that the motor is dusty and the engine was not specially washed, that is, it is clearly visible that there are no leaks.

Either way, smudge detection is a cause for concern and / or bargaining. A clean motor should also be alarming, which will require more thorough inspection. The best option an engine can be considered, which is covered with a small layer of old dust, while it does not have smudges.

Checking the condition of oil and antifreeze

If you don't know how to check diesel engine when buying or you are interested in checking gasoline unit, then one should start by assessing the state of technical working fluids inside the internal combustion engine. These are engine oil and coolant.

• Let's start with the oil. The first step is to unscrew the oil filler cap. Ideally, the lid itself should be free from obvious oily stains on the outside, the inner surface should also not be dirty, with traces of oil foam, etc. The last statement is also true for the neck walls.
• Then you can get oil dipstick and assess the condition of the oil. If it is fresh, transparent, free of foreign impurities and foam, then it will be difficult to quickly determine anything. Black oil indicates that either the lubricant has not been changed for a long time, or as a result of general contamination of the internal combustion engine and the presence of malfunctions.

It should be especially alarming that the oil in the engine can foam, that is, it is formed. In this case, it becomes obvious that liquid from the cooling system gets into. Note that in such a case, either immediately bargain with the seller for the cost of a similar contract motor /, or stop further inspection.

As for checking the engine on the cooling system, the task is to determine the breakthrough of gases and their entry into the specified system, as well as to identify the possible appearance of traces of oil in the coolant. For diagnostics, just open the cover expansion tank... If traces of oil are visible, the coolant is bubbling in the reservoir with the engine running, then the problem is obvious.

In some cases, the culprit may be a broken one, while in others, the hidden probabilities should not be ruled out.

Diagnostics of the engine condition by spark plugs

Spark plug testing can identify a variety of potential engine and engine problems.

Pay attention to things like:

• oiling;
• black, red or white carbon deposits;
• traces of unburned fuel;

The above and other signs are a clear indicator of certain problems. It is worth considering, since checking the engine by the color of carbon deposits and the state of the spark plugs is effective method only subject to certain conditions,.

Extraneous sounds and engine vibration

Evaluation of engine operation at the initial stage involves the identification of extraneous sounds, triplet, misfire and ignition of the mixture, as well as other failures in the operation of the internal combustion engine.

• After the engine has been started, you need to listen to its operation, as well as look at the level of shaking and vibrations. If possible, you can use a stethoscope, which will allow you to listen to hidden defects and localize suspicious noises.

Immediately, we note that knocks of different tonality and frequency, as well as uneven operation, indicate the presence of problems. If Gas engine works like a diesel engine, when the gas is pressed, dips occur, the unit shakes strongly, etc., then malfunctions are obvious.

• Both various systems (ignition, power supply) and individual units inside the internal combustion engine can fail. Crankshaft, pistons, hydraulic lifters or valves, connecting rods, etc. can knock. Shaking and vibrations are a consequence and a sign of breakdowns, however, the possibility of problems with the engine mountings should also not be ruled out.

Exhaust color analysis when checking the engine

The color and intensity of the exhaust, as well as the composition of the exhaust gases, in many cases clearly indicates the presence or absence of problems with the engine and its systems.

Let's start with the fact that on a properly warmed up injection motor in the warm season, no smoke is practically visible. There is also no exhaust smell. In the case of the carburetor, you can sometimes observe a slight smoke of a grayish-white color, the smell is clearly present.

So, if the engine runs smoothly, does not smoke, does not knock or vibrate at idle, and also responds quickly and clearly to pressing the gas pedal, then you can make a test drive.

Let's make a reservation right away, a short-term ride will not be enough. It is important to evaluate the operation of the unit in different modes, and also warm up the engine to operating temperatures. For this reason, you should count on a distance of at least 10-15 km.

To solve the problem, it is necessary to offer the car seller a reasonable compensation for the spent fuel and time costs. Next, you need to ask the owner, who will be with you in the car, not to make noise. You will also need to turn off the speaker system in order to be able to listen to all extraneous sounds.

• First of all, take a look at the dashboard, not. Simultaneously evaluate the sound of the motor when accelerating, during, with sharp acceleration, etc. Also, while driving, you can listen to the engine alternately with the driver's and / or passenger's window open and closed.

Pay attention to jerks, vibrations, knocks and whistles while driving. If nothing of the kind is found, then at the end of the trip, immediately open the hood and assess the external state of the heated internal combustion engine. The presence of fresh smudges on a clean engine will indicate problems that the seller wanted to hide, having previously washed the engine compartment

• Check the oil level and condition again, also let the unit cool down a little and look into the expansion tank, assess the condition and type of coolant. Smoke should not come out of the tank, there should be no oil stains on the surface of the antifreeze.
• If the situation allows, you can re-unscrew the candles and re-evaluate their condition. In some cases, it is possible to negotiate with the owner and even produce (if the buyer has a compressor).

As you can see, a superficial inspection and inspection of the engine before buying allows you to reveal a large number of hidden defects with the right approach. If you are not confident in your abilities, then ordering a comprehensive diagnostics would be the right decision. power unit and the whole car at the service station. Experts will conduct, indicate the availability possible problems and they will immediately announce the approximate cost of the repair.

In the future, the information received can be used as a weighty reason for refusing to purchase or reasoned bargaining. Finally, we add that for quick diagnostics of cars with it is useful to have a compact diagnostic. The device allows you to quickly scan the system for errors, as well as evaluate the operation of engine systems in real time.

Undoubtedly, for any motorist, even the smallest breakdown causes stress and resentment, not to mention if the engine has undergone a breakdown. With severe wear of engine components and mechanisms, it appears first of all: weak traction, increased fuel consumption and lubricants , increased smoke in exhaust system and the consequence of which is the coking of the parts.

The choice of solutions in such a situation is not great, or to produce overhaul motor or buy a used engine (contract). Units are counting on the purchase of a completely new power unit, and for this reason, we will not even touch this topic.

Is it possible to check the removed engine

In order to carry out a complete and high-quality diagnostics of the motor, it must of course be installed in the car. But what if there is no such possibility. Do not install every contract engine, just to check its serviceability.

For this case, we, together with engineers and specialists in the operation and repair of cars, have prepared the most basic and effective troubleshooting techniques for removed engine... Many of them have been known to you for a long time, and some will be learned for the first time. But in any case, one should adequately and judiciously understand that in such a situation, it is certainly not possible to check the engine for 100%, but only the risks can be minimized when buying a used engine.

At the very beginning, of course, I would like to focus your attention on appearance contract engine... The seller very often assures by phone that his "product" has wound less than 100 thousand kilometers, and sometimes less than 50. It is immediately worth noting the fact that up to 70-80 thousand kilometers, any new engine rarely has leaks and fogging on block, from under gaskets and oil seals. So if you saw a motor covered in oil, and the seller assures that the mileage is only 60 thousand, do not believe it. (but be careful, the product can be washed and rubbed) Further, for checking, it is recommended to take a small set of wrenches and gloves with you. In those cases, if the seller does not allow you to unscrew something and see, it is probably better to refuse. But here, as they say, everyone has their own head ... Diagnostics will take no more than half an hour, and wasted money cannot be earned in 30 minutes.

What does the soot on the candles talk about?

To check the correct operation of the main engine systems, it is recommended to unscrew all spark plugs from candle wells... Look closely at the color of the electrodes on the candles. On a working engine, they should all be the same color. It is not allowed if one of the electrodes of the candle has a clearly different color. Today, most gas stations add various additives and components to gasoline, which, in turn, burning in the cylinder chambers, can create plaque on candles of absolutely any color. Therefore, it makes no sense to understand this. The main rule here is that there is no black bloom on the candles, with an oily film or even drops. Often the cause of these deposits is incorrect operation. valve stem seals... What is important is that their failure is a sign of either a high mileage or poor quality service. As a rule, their replacement is required when the mileage is 200-250 thousand kilometers.

Inspection of cylinders and manifolds

Look through the spark plug holes into the cylinders, shine a flashlight if necessary. If a timing belt (chain) is installed, turn the engine crankshaft, thereby you can verify the integrity piston group... Screw the spark plugs into the mounting places, and then turn the crankshaft a couple of turns, while a characteristic and rhythmic load should be felt in cycles.

If the timing belt or chain is removed from the engine, it is strictly forbidden to do so !!!

Carefully inspect the holes for the intake and exhaust manifolds. Here you need to look first of all, the operation of the valves of the cylinder head. Check the integrity and functionality of the valve actuators by rotating the crankshaft. If the design of the motor allows you to reach the valve, then check it for play in the guide sleeve. To avoid injury, it is best to do this with a small pliers or hook. A strong backlash in the valve guides (more than 1 mm) appears, as a rule, with a mileage of more than 200 thousand kilometers. You can check only those valves that are in the maximum open position. If you find a large play in the valve guides, it is better to abandon the engine right away.

Unscrew the oil filler cap

For a clearer picture of how the engine worked before it was removed, unscrew the oil filler neck and look at it from the back. A fresh engine with timely and high-quality maintenance, the cover must be clean and there must be no deposits. Traces of black oily soot with clots are the result of operating the machine without timely replacement oils. In the event that there is foam or emulsion on the back of the lid in the color of "coffee with milk", then the coolant gets into the oil and the cylinder head gasket is most likely broken. Also inspect through the opening of the neck, the condition of the timing. Similarly to the lid, there should be no deposits and deposits inside, ideally everything should be shiny and enveloped in yellow or yellow-black oil. Seeing "salted" deposits, it is better to immediately abandon the engine.

Checking the play in the crankshaft

This procedure can only be done with the timing belt (chain) removed or weakened. Grasp the crankshaft with your hand, it is more convenient to do this from the timing side. Stagger the shaft in 2 planes. Only a slight horizontal clearance is considered normal. In the event that there is vertical play, it is better to refuse this engine, since this is a direct sign of bearing wear. crankshaft, which directly appears with runs of 250 thousand kilometers.

No one has ever sold a car because it drives very well or is very cheap to maintain. You should always keep this in mind when looking at used cars, no matter how closely you look at it from afar. However, used does not always mean bad, in fact, even very old cars can last a lot if they are well looked after. Before you even get to your wallet, you will definitely want to think it over and make sure that you never make a purchase that you will soon regret. The first and foremost thing you should pay attention to is the engine.

Steps

Part 1

Check the vehicle for spots, drops and dirt underneath. Before you quickly look at the car through the window, get up on one knee and check the bottom of the car for spots, drops or dirt. If they are there, try to figure out their age, are they old oil marks or fresh stains? Is there dirt in there that is still dripping?

Determine which particular liquid has formed a puddle. Puddles can also be due to oil leakage from the tube brake system cooling systems, transmission systems, power steering, or even windshield cleaning fluid. If you find a wet spot, you may want to poke your finger at it.

• The reddish liquid is probably transmission fluid transmission boxes. Black liquid is usually just an indicator of old oil. Caramel is the color of fresh oil, or old power steering oil or old brake fluid... A green or orange liquid is probably a refrigerant.
• Be aware of clear puddles, which could be just water from rain, the engine was washed, or the air conditioner was running recently. Once you taste the stain with your fingertip, you can tell if it's oil or water. If the stain looks like both, take a look around and pay more attention to the next steps.

1. Check the chassis. Sellers often attach a flexible hose to the car they want to sell, and some even try to clean the engine compartment, but usually inspect the underside of the car for puddles or no puddles; how clean the parts are. You may be able to ignore simple dirt, and even be prepared to see a certain amount of road dirt and oil stains (This is a car, after all), however you will want to inspect the car for liquid stains that have recently formed and have not been removed.

   • Trace wet spots, dark spots and oil residue by reversing Special attention on the sump and on any seams or gaskets you may notice. It is better to have the remnants of dirt, which appeared as a result of the elimination of problems in the car, than soon have to repair the car, because it has never been repaired.
   • However, new, wet dirt or oil can indicate some problems, so take what you see into account. Do not hesitate and point out imperfections (perhaps use a paper towel) to clearly see how dirty, wet, slippery or hardened the dirt can be.

2. Determine if oil leakage is a real problem for you. If you do see drops or traces of wet dirt or grease, try to figure out where they come from. The leak is already sufficient reason to look at another car in the lot, but it's up to you to decide whether this is a sufficient problem that will prevent you from purchasing a car.

   • Some people will willingly add oil to replenish the level in the sump and can drive safely for many years without serious consequences or inconvenience. Some leaks are minor, so the oil can last for many months, while in some cars this problem is exacerbated, which can soon lead to serious breakdowns.
   • If nothing is clearly flowing, dripping, and hardening due to dirt, you can calm yourself down. Many possible engine problems can only be dealt with if there is no visible fluid leakage.

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When buying a used car, the most important factors are the condition of the engine, transmission and bodywork. The fact that the interior of the car is clean wheel disks beautiful, does not say anything if the engine has hidden problems, or was poorly maintained by the previous owner. Engine repairs are very expensive. Of course, it is difficult to assess the mechanical condition of an engine during a quick test drive, so we strongly recommend asking a qualified mechanic to inspect the vehicle before purchasing. To help you be more informed, here are some tips on how to determine the condition of your engine before buying a used car.

Check the entries in the car's service book.

The service book may be missing, and you should not completely trust him. But the entries in service book provide some evidence that the vehicle has undergone regular maintenance. Pay attention to the oil change records. You will know that oil changes were made on a regular basis or not, which is fraught with engine wear. As a rule, the manufacturer indicates the engine oil change interval in kilometers (or in miles). There are also restrictions in the time period - 3 months -6 months - 1 year. The car can stand and not go on the road, and the oil in the engine will still lose its properties - that is why the manufacturers have introduced a time limit. Depending on the manufacturer, the recommended oil change interval ranges from 7,000 to 15,000 km. We determine the operating conditions, and they are difficult for us, which means we need to change it 2 times more often. We count at 10,000 km. No more so that the engine does not break down.

We look at the records of the replacement of timing belts. If the timing belt or timing chain has not changed, replacing will cost you a lot of money, depending on the complexity of the engine. By postponing belt replacement, you may have to repair the engine if the belt breaks.

When inspecting a used car, inspect the engine carefully. It's good to have a flashlight with you. Make sure the engine is off, the transmission is in neutral or Park, and parking brake switched on. What you need to watch is leaks, a smell of burning oil or antifreeze, signs of poor repair, or a lack of regular Maintenance and "racing" modifications. The sealant coming out from under the gaskets, missing nuts and bolts should alert you. Just because everything looks clean and shiny does not mean everything is in order. Car dealers clean, wash, and run a marafet before showing them to customers.

Let's take a look at a few examples:

Signs of poor service

Acid deposits on the battery terminals

If the battery looks like the photo, it is unlikely that this vehicle has been regularly serviced.

The smell of oil under the hood

Brilliant engine compartment This engine looks clean and shiny, but you smell a strong smell of burning oil. This is a sign of possible future problems, think twice before buying such a car.

Leaks

Leaking coolant

This car is operating normally, but close inspection reveals a coolant leak from the radiator. At a minimum, this car requires a radiator replacement, but sometimes, a cracked radiator can be a sign of more serious problems. The best thing is not to buy a car with such a problem.

Check for oil leaks. They may not be visible from above, advice - look under the car using a flashlight. Check the underside of the engine and transmission. Everything should be dry. There may be a little dampness, which is not so critical, but there should be no leaks.

Low oil level

Check the oil level. The oil looks dirty and the level is low. This means that either this engine is consuming oil, or the oil change was carried out a long time ago. The engine will wear out faster when the oil level is low. Typically the oil level should be close to the "Full" mark.

Normal oil level

The engine oil in this car looks clean and the level is normal. It looks like the oil change was done recently.

This test has a lot to say about the engine. If you are unsure of your knowledge, ask a mechanic you know to help you. With the engine off, remove the oil filler cap and look underneath.

Check under oil filler plug

For example, in the photo on the left, you can see that there is a lot of black carbon deposits under the lid. Visible parts internal engine and the cork itself looks very dirty. This is usually a sign of poor service. Everything looks clean in the right photo.

Increase in engine power.

Be careful if your used car has been tuned. Done right, the changes can greatly improve the vehicle. However, poorly "chip-tuned" an engine can lead to many problems. Especially if parts were changed (camshafts, crankshaft, connecting rods, etc.). If the car was subjected to "chip-tuning", most likely the engine was running at full load.

Starting a cold engine can reveal many hidden problems. The best way to reveal hidden problems, this is cold start. The first thing that this will show is the condition of the battery, because if the battery is bad, then you may have to buy a new one. After starting the vehicle, all warning lights are on. dashboard should go out. For example, the indicator " Check Engine". This means that the engine computer has detected some kind of malfunction. This may be a minor problem, but the fix will probably cost a lot of money. There is no other way to know how serious the problem is until computer and instrumental diagnostics have been carried out.

Exhaust smoke

Blue smoke from the exhaust pipe of a car Here is another example: start the car and notice blue-gray smoke from the exhaust pipe. The exhaust smells like burnt oil. Blue smoke means the engine is burning oil. Better to refuse such a purchase.

Test Drive During a test drive, listen to the engine, watch for vibrations, check how the engine pulls. When starting, the engine should run smoothly, without shaking or hesitation. If you feel that the engine is noisy, there are dips during acceleration, it does not accelerate smoothly, then there are problems. Speed idle move must be stable. Travel as long as possible; sometimes problems cannot be detected on short trips. It is best to try the car in all modes: acceleration, braking, pulling away, at high speed. Monitor the engine temperature on the dashboard. After the engine has warmed up, the temperature gauge should remain somewhere around the middle of the scale. Even if all appears to be okay, we strongly recommend that you get your used car properly inspected by an independent mechanic before purchasing.

Read 1925 once

When buying a used car, the iron "heart" is the second most important unit after the body. Therefore, when buying a used car, you definitely need to know how to check the health of the engine.

Visual inspection

Before checking the engine, inspect the documents, the body, the interior. Let the motor stand for 10 minutes. (if the owner has already started it) to assess the oil level. Move away from a vehicle that has a level below the minimum mark.

Look into the oil filler neck. Have good motor with mileage, the oil should be slightly darker than the new one, and the cylinder head parts should be without thick resinous, varnish deposits and carbon deposits. The oil of even a serviceable diesel internal combustion engine darkens after 1 thousand km. Inspect the joints between the cylinder head and the BC. Ideally, the joint should be free of oil traces. To eliminate the "fogging" of the cylinder head cover or pallet, in most cases, you can replace the gasket. Inspect the car from the pit to make sure that the problem is in the gasket and not in the crankshaft oil seal. The amount of subsequent investments depends on how to check the engine.

With the permission of the owner

If the owner of the car allows you to assess the condition of the turbine, remove the air pipe going to the cold part. There should be no oil. In the opposite case, the turbine "throws" oil, which will require investment in a new "snail" or restoration of the old one. Of course, there will be such a car. Check the condition of the impeller by shaking it by hand. Only slight axial play should be observed.

It is also advisable to unscrew the candles to make sure there is no oil deposit ( clear sign CPG wear). The general state of the engine's vitality is best determined by measuring the compression and checking the combustion chambers for leaks.

Launch

An uncertain start of the power unit may indicate the following malfunctions:

As you can see, the list has items that will require a significant investment to be eliminated.

Even when talking with the seller, condition the fact that you want to look at cold start motor. Since starting the engine after a long idle time is the most indicative for determining the state. This is especially true if you buy a diesel engine.

It is best to buy a Diesel cycle motor in winter. If, after a long downtime, the car starts up "off the bat", be sure that with fuel equipment, glow plugs and compression are all good. At the very least, you can be sure that there is no surprise waiting for you the next morning.

After warming up the engine to working temperature, switch off and start the vehicle several times in a row. Be sure to do this if you buy diesel car... Since the engine, powered by diesel fuel, can start well when cold and very bad when hot. This will indicate problems with the plunger pair. We focus specifically on the diesel internal combustion engine, since it is much easier to solve the problem with a hot start of a gasoline car.

Motor operation

The serviceability of the engine is largely determined by the absence of the following symptoms:

• increased vibrations;
• , metallic ringing sounds.

You should definitely look beyond. A particular danger is gray smoke, since it indicates oil burnout. At best, get off with replacing the valve stem seals; at worst, overhaul of the motor is inevitable. If you run a cold, used diesel engine, a small amount of gray smoke is acceptable. After a few minutes of work, it should disappear. On idle there should be no black smoke. If the car has been removed particulate filter, then the appearance of thin smoke is permissible at hard pressing on gas to the floor.

With the engine running, carefully open the oil filler neck. If you see smoke, the valves are not sealed. Traffic fumes break into the cylinder head cavity, also pull out the dipstick at idle. The presence of smoke will indicate a poor state of the CPG or a clogged crankcase ventilation.

After the engine reaches operating temperature, open the expansion tank cap. Only be very careful, as there is a chance to burn yourself with hot antifreeze. Ask the owner to raise the engine speed several times to 4-5 thousand. Air should not come out of the pipes. The opposite will indicate a breakdown cylinder head gaskets or a crack in the block. Also, there should be no oily deposits inside the coolant reservoir.

Test Drive

The condition of the engine directly affects the dynamic performance of the vehicle. Try to ride in all engine modes (low, medium, high rpm). When you press the gas sharply, there should be an appropriate response. If the revolutions are floating, or the engine "dulls", if desired, it will accelerate sharply - financial investments will be required.

Diagnostics

The best way to check the condition of the "heart" of the car is to conduct computer diagnostics... You can diagnose yourself using the OBD-II adapter and the corresponding software... Unfortunately, the universal kit rarely gives useful information, therefore, it is better to contact specialists with specialized equipment. Especially when it comes to choosing an expensive modern car.

Since it is very difficult to check the engine when buying a premium car yourself, contact dealership... There you can measure the compression, as well as inspect the cylinders with an endoscope for scoring.