How can you make sure that it is the connecting rod bearing that is knocking without disassembling the engine?
- Knock in the VAZ 2110 engine, 8 valves - 2 answers
- Is it possible to install the main crankshaft cover from another engine? – 1 answer
- Which is the best crankshaft pulley for VAZ 2110 - 1 answer
I fell for this twice. There is a crackling noise when the engine is running and the oil pressure indicator light is on, but the oil level is normal.
Without disassembling at all, you can only localize the place of the knock. This is what I answered in your previous question (although there you asked about knocking on the Golf, and here the question is on the VAZ, but in principle - by definition of knocking, there is no difference). To check this version with minimal work is to drain the oil from the engine, remove the pan and feel the connecting rods (this can be done by holding the connecting rod yoke); which has the most wear on the liners - it will hang up and down on the crankshaft. If the knock was coming from this particular cylinder, and the connecting rod bearings are not worn out, then disconnect the connecting rod yoke, remove it together with the bearing, and pull the connecting rod up and down (not too much so that the piston remains in place) - if the connecting rod dangles, then there is a problem in a worn piston boss or in a broken pin, or a worn connecting rod head bushing.
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Knock in the VAZ 2110 engine, 8 valves
Which is the best crankshaft pulley for VAZ 2110
Is it possible to install the main crankshaft cover from another engine?
It is well known that a car engine consists of a large number of moving elements that are under mechanical and thermal load. Also, each type of internal combustion engine has a limited resource, that is, parts gradually wear out. As a result of such wear, a knock appears in the engine over time, the engine begins to smoke, draft is affected, oil and fuel consumption increases, etc.
Also, various problems can occur in the engine, which lead to noise and knocking even on “fresh” units. In this case, we are not talking about wear, but about breakdown, which becomes the main cause of extraneous sounds. It also happens that the engine knocks only “cold” or “hot”.
Also, a knocking sound in the engine may appear and disappear in different modes, or the engine knocks regardless of the degree of warming up and the load on the internal combustion engine. Next, we will talk about what can lead to knocking, as well as how to determine what is knocking in the engine.
Why does the engine start knocking?
First of all, you need to understand that both the engine itself and the attachments can knock. For example, the owner may hear noise and knocking from the pump, generator, power steering pump, etc. If we talk about the engine itself, knocking noises can appear as a result of wear or damage to the connecting rod bearings, pistons, in case of problems with the timing belt, etc.
So, if knocking suddenly appears in the engine, the main reasons may be:
- decrease in engine oil level or loss of its properties;
- the engine began to overheat for one reason or another;
- the power unit is worn out, there are problems with the CPG and the crankshaft;
It is also important to consider whether the engine knocks only when it is cold and/or when it is hot. It is also important to determine whether such a knock is intermittent or constant. The fact is that the power unit does not always knock constantly.
Often knocking noises are heard only when cold, but disappear after warming up. Note that in this case, on some internal combustion engines, the knocking of the pistons in the cylinders is heard when cold. The reason is that the cylinder liners are worn out, which leads to the formation of a gap between the piston and the cylinder wall.
However, given that the pistons are aluminum, they expand after warming up. It is not difficult to guess that after expansion the gap becomes smaller and the knocking in the engine disappears when it is hot. Also, on a cold engine, the timing chain may make noise.
Piston
When the piston wears out, a knocking noise may also occur. When listening, it can be found in the middle part of the cylinder. Moreover, the knocking will be observed only at idle speed and slightly higher. At rpms above 2000 it will not occur. This happens for the following reasons. The piston is released evenly. But, in any case, the upper part fits more tightly; it is held in place by compression rings, which expand as needed. When operating at low speeds, the skirt of a worn piston vibrates. After gaining speed, it stabilizes and the knocking disappears.
When such a problem occurs, a major engine overhaul is inevitable. Of course, you can only replace the pistons. But, for greater reliability, you should replace the crankshaft liners and grind it. Otherwise, there is a risk of the crankshaft jamming in the future.
connecting rod
. Sometimes the connecting rod can be the cause of the knocking noise. More precisely, its bushing. In fact (in this case) there will be a knock at any speed. But, it will only be heard well at idle or when braking the engine. In other cases, it can only be heard by listening to the unit. The repair is almost the same as in the case of pistons. And you shouldn’t delay the repairs. The consequence of a bushing breakage is usually a “fist of friendship”. That is, the connecting rod punches a hole in the cylinder block.
Other reasons
. Sometimes, knocking can occur for other reasons. A knocking sound at idle may indicate wear on the camshaft bearings. The sound is quite dull. It can come from the front or rear of the engine. Often a camshaft knocking sound is mistaken for a problem with the pump bearing. This is due to the close location of these parts. If the pump malfunctions, the engine begins to overheat.
Conclusion
. The engine is the heart of the car. Therefore, any problems with it should be resolved as quickly as possible. A knocking sound in the engine at idle speed is in most cases a sign of a malfunction. Timely identification of the source of noise will allow you to eliminate the breakdown as quickly as possible and with a minimum of costs. Neglecting this symptom can lead to more serious problems.
Knock in the cylinder head
Usually, when it comes to knocking in the cylinder head area, valves or hydraulic compensators are most often knocking. Also, valve knocking can be heard on engines with hydraulic valves, and not only in units that have mechanical valve drives.
One way or another, the knocking of hydraulic compensators must be eliminated with an additive, flushing or replacement, and the valves must be adjusted. If these procedures do not help, then there is a high probability of wear on the camshaft cams.
There may also be a gap between the pusher and the seat, the end of the valve is worn, the adjusting washers have become unusable, etc. Even in the timing belt, noises and knocks are often produced by the chain; in belt-driven mechanisms, tension rollers often fail.
It should be remembered that the valve bushings and seats wear out in the head, and the camshaft bed gradually develops. The knocks on the cylinder head themselves can vary in tone from ringing high-frequency to low and rumbling.
It is important to understand that driving with knocks and noises in the gas distribution mechanism is unacceptable for a number of reasons. For example, increased gaps worsen the tightness of the combustion chamber, the engine loses power, and rapid wear of timing parts is noted.
If the gaps are too large, the shims may fly out, causing the camshaft, etc. to become unusable. When the hydraulic compensators knock, the camshaft cams wear out greatly.
Knock in the engine block
The appearance of a knock in the BC, especially if the knock is localized in the lower part of the engine, often indicates problems with the crankshaft. Such knocks indicate a serious breakdown; the engine must be stopped operating. Otherwise, the crankshaft may become unusable.
If the connecting rod bearings are knocking, further driving will lead to the connecting rod cap being torn off, and then the cylinder block will be broken. In this case, it may be necessary to replace the entire engine with a contract one.
The knock of the connecting rod journals is metallic and sharp, especially if you press the gas. Also in such a situation, the oil pressure drops and the oil pressure light on the instrument panel lights up. A decrease in pressure leads to the fact that the engine can seize after just a few minutes of operation under load.
The crankshaft journals may also knock. This kind of knock is lower, vibration goes through the engine. The reason is that as a result of wear on the main journals, a gap appears between the crankshaft journals and the supports in the block. This type of knocking noise may also appear due to low pressure in the lubrication system, which leads to scoring on the shaft journals.
Note that if the problem is in the main journals of the shaft, you can get to the repair site under your own power, which cannot be said about knocking connecting rod bearings. However, even in this case, no serious loads can be placed on the internal combustion engine, and the engine itself must be repaired immediately.
Now let's move on to the CPG. If the piston group begins to knock, this indicates an increase in the gap between the piston and the cylinder, as well as the occurrence of defects both on the liner and on the piston itself.
It should also be noted that the cause of knocking can also be the piston pin and its connection with the connecting rod. For example, if the pin is pulled out of the piston, then it can hit the cylinder wall. The reason is insufficient pressing of the pin or the stopper on the piston has flown out (depending on the type of fit of the piston pin on a particular internal combustion engine, which can be “hot” and “floating”).
Knocking in the engine when hot
While the engine is cold and the oil is not warmed up, the gaps in the parts do not manifest themselves in any way. The knocking noise becomes more pronounced as the oil thins. There may be several reasons:
- increased gap between the crankshaft journal and the main bearings;
- in connecting rod bearings when a sufficiently large gap is formed between the crankshaft journal and the support;
- when cracks appear in the piston skirt or the piston pin itself.
It is possible to diagnose which of the above options leads to knocking only by disassembling the engine. Here you will need the help of a real specialist. Disassembling an engine is one thing, but repairing the breakdown and putting it back together is a completely different task. If you don’t have special skills, you shouldn’t risk doing repairs yourself.
How to determine what is knocking in the engine
We also recommend reading the article on how to accurately determine what is knocking in the engine. From this article you will learn about the various available methods for diagnosing and identifying knocks and noises in the internal combustion engine.
In this case, diagnosing the problem is easier than in the case of the engine. To check, you need to remove the belt from one or another unit, and then evaluate the noise level by starting the internal combustion engine. Also, after removing the belt, you should rotate the shafts and pulleys to accurately determine the source of the knocking or noise.
What's the result?
As you can see, there are quite a lot of reasons for knocking in the engine. In this case, knocking in the engine may appear and disappear (depending on the heating and the degree of load on the internal combustion engine).
To accurately determine the breakdown, in some cases the engine must be disassembled and troubleshooting carried out. This procedure allows you to assess the condition of the parts of the cylinder head, crankshaft, timing gear, etc. for the development and increase of gaps, scuffs, cracks and other defects.
An engine repair specialist determines the possibility of restoration (repair) or decides to completely replace worn and damaged elements. For example, in many cases the crankshaft is ground, the cylinder block is lined/bored, while pistons, piston rings, connecting rods and other parts are usually replaced. As for the timing, the camshaft also needs to be ground or replaced, and the valves are often replaced with new ones.
Finally, we note that engine repair, both partial and major, is an expensive and complex procedure. For this reason, you should use only high-quality spare parts and entrust such work only to proven and qualified specialists.
Experienced drivers know that the most dangerous knock in the engine is associated with the connecting rod. If its liners wear out or another breakdown occurs, then it will not be possible to deal with it promptly. Filling with oil with a high viscosity index, using late ignition, or using new linings will no longer help here. All these measures can only temporarily get rid of the knocking, but they will not eliminate the root cause.
Diagnostics
Knocks in the engine can be caused by a variety of reasons. Experienced mechanics know a large number of different examples of the appearance of noise, even funny ones. For example, when the knocking of the crankshaft was mistaken for the tapping of the unscrewed protection of the pan. In order not to be frightened by such trifles, let's look at how to find the cause of the knocking.
First, determine when the sound occurs. First of all, listen at what stage the noise appears. Usually there are 3 scenarios:
- Knocks at idle;
- The sound is heard all the time the engine is running;
- Increasing knocking or noise at high speeds.
This will determine the direction of the search.
Knocks at low speeds are usually associated with a malfunction of the lubrication system or incorrect valve settings. A constant knocking noise occurs when there are problems with the crankshaft and when the crank mechanism is worn out. An increasing sound occurs when there are problems with the timing belt, as well as in case of wear of the bearings included in the engine structure. To clarify the source of the problem, you need to listen to the engine while running. Conclusion
. As a rule, the worst thing for a car enthusiast is engine problems. Therefore, people are interested in knowing where the knocking in the engine comes from when the speed increases. Often, this is a harbinger of a fairly serious breakdown. Therefore, it is best to identify and eliminate the problem as soon as possible when this symptom appears.
