Why do hydraulic lifters knock on a cold or hot engine. Hydraulic lifters knock: causes and what to do

An article on what measures to take if hydraulic lifters are noisy - causes of knocking, methods for eliminating the problem. At the end of the article - a video on what to do if hydraulic lifters knock.

If the gaps are not adjusted properly, then the valves in the timing will also close incorrectly, as a result of which they will burn out and a knock will appear. In addition, the size of the gaps can also change with severe wear of the timing mechanisms during operation. Since the adjustment of valve thermal clearances is a rather complicated and responsible matter, hydraulic compensators began to be used instead of levers and washers that require complex adjustment.

The hydraulic compensator (hydraulic pusher) is a small mechanism that automatically adjusts the thermal clearances of the timing valves, without any additional settings. This miniature mechanism automatically changes the gaps to the desired size under the influence of a spring and engine oil pressure.

1. Engine oil problems.
2. Hydraulic lifters are mechanically worn or damaged.

"Oil" problem

The correct operation of hydraulic lifters is highly dependent on oil factors such as:

• quality, freshness, and compliance with the recommendations of the engine manufacturer.
• level.
• pressure.

When the oil level in the engine exceeds the norm, it foams in the crankcase and loses its uniformity., followed by a change in indicators: viscosity, thermal conductivity and lubrication. The speed of oil passage through the channels depends on the viscosity, which directly affects the operation of the hydraulic compensators - after all, with a strong thickening of the oil, the channels may become blocked, and the liquid will stop flowing (or begin to flow more slowly) into the compensators.

On the other hand, with a highly diluted oil, the pressure in the oil system may drop, and the oil will also poorly flow into the compensators. And when the oil level in the engine is below normal, the oil pump sucks in air when delivering fluid to the compensators, which also negatively affects their operation and leads to knocking at high engine speeds.

Insufficient oil pressure may be due to a pump failure., as a result of which oil will be pumped into the hydraulic compensator slowly or not delivered there at all. In addition, a decrease in pressure inside the compensator may occur due to oil dilution or clogging of the oil channels of the hydraulic compensator itself.

Wear and mechanical damage

• In the course of heavy operation of the engine, the formation of scoring and dents can occur on the body and the hydraulic compensator plunger. In this case, a characteristic knock will be heard at any speed of rotation of the timing camshaft.
• If faulty check valve, then the hydraulic compensator will knock on a cold engine, immediately after it starts. But the noise will stop as the rpm increases. Also, the knock may disappear on a warm engine, also with an increase in speed.
• If the plunger pair is worn out, then a knock will appear on a warm engine, but it will not be there if the engine is restarted slightly cooled down.

1. Oil change and oil filter with engine flush.
2. Inspection (diagnosis) of hydraulic compensators and their replacement or flushing (flushing compensators is an ambiguous question).

The first stage is the easiest and most affordable: drain the old "working out", fill in the flushing liquid and turn on the engine for 15 minutes. Then drain the "flush", install a new oil filter and fill in new oil.

The second stage is more complex and time consuming.. Here you will need to inspect and check the hydraulic lifters themselves, for which you will have to remove the valve cover.

The most common diagnosis of hydraulic lifters is their punching. To do this, it is necessary to release the compensators from the pressure of the camshaft cams by turning the camshaft accordingly (with the short part of the cam towards the compensator so that the cam does not press on it). It is better to push the expansion joints with a wooden pin so as not to damage their surface.

Serviceable hydraulic lifters are very difficult to push through, and faulty ones are pushed through quite easily. When pushing through all the expansion joints, you can compare which of them are difficult and which are easy. Those expansion joints that are pressed through easily compared to others are best replaced.

Flushing the hydraulic lifters themselves is an ambiguous question, since theoretically the compensators should be automatically flushed when flushing the engine at the oil change stage. Therefore, the removal/disassembly/flushing/assembly/installation of expansion joints can be unnecessary work and a waste of time. Especially when there are 16 hydraulic lifters. In this regard, the removal and disassembly of hydraulic lifters is recommended only for their more thorough inspection, when there are no other options for solving the problem. And at the same time, you can wash.

Also, the removal of compensators is advisable if they can be considered obvious mechanical damage and deformation.

• For more reliable and durable operation of hydraulic lifters, it is recommended to change the oil a little ahead of time. For example, if according to the maintenance regulations it is necessary to change the oil after 15 thousand kilometers, then it is better to change it 2 to 3 thousand kilometers earlier.
• For normal operation of new expansion joints, it is not recommended to remove the factory preservative grease from them during installation.
• If you need to replace one or more faulty compensators, then it is better, if possible, to change everything at once, since if one breaks down, the rest will soon “crumble”.
• After replacing faulty (or old) hydraulic lifters with new ones, before starting the engine for the first time, it is recommended to rotate the crankshaft by the ratchet 5-6 times so that the plunger pairs of the new hydraulic lifters take the correct working position.

Conclusion

As practice shows, The most common cause of noisy operation of hydraulic lifters is the use of bad oil - or Low quality, or an old (used), or engine not recommended by the manufacturer.

Therefore, in most cases, the problem of noisy operation of expansion joints is solved already at the first stage, by changing the oil and filter, as well as flushing the motor, during which the expansion joints should also be washed. And the knock of “hydraulics” due to their wear or damage happens much less frequently.

Video on what to do if hydraulic lifters knock:

The most common malfunction of modern engines is the knock of hydraulic lifters. There are many reasons, most of them related to the quality of the oil. What to do with this malfunction and how to deal with it will tell this material.

What is a hydraulic lifter and how does a hydraulic lifter work?

The hydraulic compensator is a simple device for automatically adjusting valve clearance, eliminating the need to disassemble the engine during its operation. maintenance. The hydraulic compensator, colloquially "hydric" is a miniature hydraulic cylinder that changes its length when injected into the engine oil.

The volume of oil compensates for the gap between the valve stem and the camshaft lobe. Oil enters the hydraulic compensator cavity through a valve with a very small hole, and exits through the natural gaps of the valve pair. How well the "hydric" works depends on the flow of oil and on the condition of the plunger pair, the absence of wear or jamming.

How to understand that it is the hydraulic compensator that is knocking

A faulty hydraulic compensator makes a sharp knock, chirp, with a frequency half that of the engine speed.

A hydraulic compensator is considered faulty if it knocks for more than a couple of minutes after starting the engine or knocks after the engine is fully warmed up. The knock is heard from above the engine and may not be heard from inside the car.

Why is the hydraulic lifter knocking

Causes of the knock of the hydraulic compensator "on the cold" (when the engine is cold):

1. Too thick oil, on a cold engine, does not enter the hydraulic compensator cavity well. It takes time for the cavity to fill with oil.
2. Clogged oil line or hydraulic compensator valve. Contaminants appear when the quality is low or when the engine oil is changed for a long time, and can also be wear products of some engine parts.
3. Worn or jammed hydraulic compensator plunger. It happens from natural wear or from the ingress of abrasive contaminants into engine oil.

Causes of the knock of the hydraulic compensator “on hot” (on a warm engine):

1. Jamming of the plunger pair of the hydraulic compensator due to normal wear and tear or contamination. Seizures on the plunger block its movement and the hydraulic compensator completely loses its efficiency. The gap is not selected and the hydraulic compensator knocks.
2. Warm oil viscosity too low, oil flows out through the gaps of the plunger pair faster than it is supplied by the pump. Poor quality oil or too thin for this engine the oil is highly liquefied when warmed up and easily flows out through technological gaps.

3. Enhanced level oil in the engine, oil foaming due to agitation by the crankshaft or due to water entering the engine. The engine oil level should be checked and only high quality engine oils should be used.

The easiest way to eliminate the sound of hydraulic lifters

The easiest and most effective way, which helps in most cases, is to add a special additive to the oil Liqui moly. The additive flushes the oil channels, removes contaminants and restores the oil supply to the hydraulic lifters. In addition, the additive slightly thickens the oil, thereby compensating for their natural wear. The additive is added to warmed up engine oil, the full effect comes after about 500 km of run.

How else can you eliminate the knock of hydraulic lifters

1. Replacement of hydraulic lifters Pros: Guaranteed result. Cons: Expensive and time consuming. It should be borne in mind that for some foreign cars, you first need to order parts, wait until they arrive, and sign up for repairs in the service. On most engines, when replacing hydraulic lifters, there will be additional costs for disposable parts, such as gaskets or sealant.
2. Thorough flushing of the oil system with special flushes, for example: Liqui Moly. Pros: Relatively inexpensive. Cons: Results are not guaranteed.

3. Perhaps, in advanced cases, it will be necessary replacing the oil pump or cleaning the oil lines engine with its partial or complete disassembly.

What will happen if you do not eliminate the knock of hydraulic lifters

If you do not deal with the elimination of the knock of hydraulic lifters, then you can drive for quite some time without any problems, but, over time, the engine will run louder, vibrate, power will drop and fuel consumption will increase, and then it will happen wear of the entire valve mechanism especially the engine camshaft. Its replacement is a very expensive undertaking.

Outcome

If the knock of hydraulic lifters repeatedly occurs, then it makes no sense to wait for the situation to worsen. Adding an additive will solve the problem and prevent the development of wear for a long time.

VIDEO

;

For the long-term operation of the car, it is important not only to visually inspect the mechanisms, but also to listen to the sounds that it makes. For example, by ear, you can diagnose a case when hydraulic lifters knock. To facilitate the operation of the car and eliminate the need to regularly adjust the valve clearance, manufacturers have developed and began to use hydraulic lifters in series. However, their use not only makes life easier for the car owner, but can cause concern about what to do if there are extraneous sounds from the engine compartment.

Article author: mudriy_lev
Specialization: repair of autogenerators and servo drives in the car.
Place of work: service center. Experience: 2 years.
Education: higher - electrical engineer, secondary special - mechanical assembly work mechanic.

The most common reason why hydraulic lifters knock is oil. The car owner needs to pay attention to the following factors that can cause the knock of hydraulic lifters:

• oil must comply with the manufacturer's recommendations
• oil change should be on time
• The oil filter is changed at the same time as the oil is changed.
• oil must be suitable for climatic conditions

The most important thing when choosing an oil is that its viscosity matches the manufacturer's recommendations. Hydraulic lifters will knock if:

• oil is too viscous
• oil is too thin

In the case of too viscous oil, hydraulic lifters usually knock on a cold one, since insufficient oil is supplied through the channels. In the process of heating the oil, it becomes more liquid and is able to freely fill the entire system. Therefore, a knock on a hot one usually goes away.

If the oil is too thin, then on some vehicles there is a situation that the oil pump is not able to create optimal pressure in the system. As a result, oil starvation occurs, and the knock of hydraulic lifters, which is more clearly audible on a warm engine. In the event of a breakdown of the oil pump, a similar situation occurs.

The same situation can arise if the oil does not meet climatic conditions.

To eliminate the knock of hydraulic lifters in this case, it is necessary to change the oil. If the oil is changed in garage conditions, then it is necessary to check the full compliance of the oil with the requirements of the automaker.

Oil during maintenance is changed for a reason

In the case of prolonged operation of the car without changing the oil, the following situations may occur that cause the knock of hydraulic lifters:

• canal pollution
• oil loss of its qualities

In the first case, the knock will appear when the engine is cold. The oil supply channels are clogged and therefore it is impossible to create the required pressure in the hydraulic compensators. In the process of warming up the oil, deposits exfoliate and oil flows throughout the system. After cooling, all the dirt will sit on the walls and re-clog the channels. This will cause knocking every time the engine warms up again.

If the oil has lost its qualities due to old age, it may begin to foam. Such oil is not able to create the necessary pressure and its prolonged presence in the engine will lead to significant damage.

If the oil is old, it must be replaced. Do not immediately fill in expensive oil. It contains high-quality detergent additives that can remove dirt from the walls. This will lead to even more clogging of the channels of the oil system. Therefore, before pouring good oil, after prolonged operation with old oil, it is necessary to flush the system with a special agent.

Knock of hydraulic lifters due to engine overheating

Engine overheating can cause oil to lose its qualities. After the engine boils, it is imperative to eliminate the cause of its overheating and change the oil.

The use of overheated oil not only causes the knock of hydraulic lifters, but also leads to increased wear of all internal combustion engine elements.

An oil change should only be carried out together with an oil filter, which can also cause knocking.

If the filter is clogged, then the oil is difficult to pass through it. This leads to a decrease in pressure in the system. In this case, the knock of hydraulic lifters from the engine compartment will be heard both on cold and hot.

A comprehensive oil and filter change can correct this situation.

Strong mechanical wear

In the event that a car with high mileage and hydraulic lifters have not changed for a long time, a knock on their part may be due to excessive wear.

A visual inspection will allow you to understand how to identify a knocking hydraulic lifter. In the event of wear on the impact surface, the knocking hydraulic compensator will be immediately visible from the dents from the camshaft. If outwardly all the hydraulic lifters look normal, it is necessary to press them one by one with a piece of wood or a screwdriver. The effort should be the same. In this way, it is possible to identify both a stuck and a hydraulic compensator that does not hold pressure.

When knocking is normal

After changing the oil, the hydraulic lifters are empty. After the engine starts to work, oil will begin to flow into them. But until normal pressure is created, knocking from the hydraulic lifters is considered the norm. During subsequent warm-ups of the engine, extraneous sounds should be absent.

The case when hydraulic lifters knock on cold or hot is not a critical breakdown, as this allows you to continue to operate the car, but in order to prevent damage to the timing elements, it is advisable not to delay the elimination of this breakdown.

Why hydraulic lifters knock, the reasons for knocking on a cold and hot engine, we will talk about all this in this article, as well as the principle of operation of hydraulic lifters. The advent of hydraulic lifters was a breakthrough in engine building, because it made it possible to create motors that do not require maintenance every 10 thousand kilometers. After all, now the gaps between the camshaft (camshaft) cams and the valve lifters were automatically adjusted, and taking into account the engine temperature.

How hydraulic lifters work

The engine's oil system supplies oil to the hydraulic lifters, causing the latter to increase in height until they reach the camshaft. Regardless of valve wear, oil effectively presses the top of the valve against the cam.

This is due to the presence of a hydraulic chamber and a plunger with a valve and a spring in the hydraulic compensator. Entering the hydraulic compensator through a small hole, oil fills the chamber, due to which the upper part rises relative to the lower until it touches the engine camshaft. Then the cam presses on the hydraulic compensator and the oil pushes through the lower part, opening the corresponding valve.

When the cam stops pressing on the upper part of the hydraulic compensator, the valve in its composition opens, pouring oil into the oil intake channel, and the engine valve closes. Then the liquid entering through the oil system fills the cavity again and presses the upper part of the hydraulic compensator against the camshaft. All this makes it possible to compensate for the effect of thermal expansion, which is the main reason for the knocking of conventional valves “on the cold”.

Why is the engine hydraulic compensator knocking

The hydraulic compensator begins to knock due to the fact that a gap appears between its cover and the camshaft cam. When the cam, descending, touches the surface of the hydraulic compensator, this does not happen smoothly, but abruptly, with a blow, which becomes a source of knocking. The reasons for this phenomenon are different. Here is a list of the most common causes:

• severe contamination of the oil filter;
• unsuitable (too viscous or vice versa, too thin) oil;
• oil produced or spoiled by products of combustion and friction;
• clogging of the oil channel of the cylinder head;
• clogging of plungers or valves with dirt from the oil; stuck valve ball.

When the oil filter is heavily contaminated, the pressure in the oil system drops. This leads to insufficient filling of the hydraulic compensator with oil and the appearance of a gap between its cover and the camshaft. After all, the speed of filling the hydraulic compensator with oil directly depends on the speed of rotation of the crankshaft. The higher the engine speed, the greater the oil pressure and the faster the filling of the hydraulic compensator chamber. The appearance of knocking at certain speeds may indicate a mismatch in the oil to the engine. If it is too viscous, then it will not have time to fill the hydraulic compensator chamber before the cam approaches, but if the viscosity is not enough, then the oil pressure will be less than necessary and the chamber will not have time to fill up again.

If the oil is not replaced on time, and taking into account the actual state of the engine, and not the regulations from the service book, then the content of soot, metal dust and chips increases in it. All these substances, getting inside the hydraulic compensator chamber, impair the operation of the plunger and valve, due to which the chamber either does not fill up or loses oil through a leaky valve. Another reason leading to the appearance of a knock of hydraulic lifters is a clogged oil channel. This is especially true for worn engines, because they have several times less mileage before changing the oil than new engines. This is caused both by a large volume of gases escaping from the combustion chamber into the crankcase, and scuffing on rubbing surfaces that fill the oil with metal dust and shavings.

How to determine the cause of a knock

It is quite difficult to independently establish the cause of the knock.

• First, it is necessary to determine which of the hydraulic lifters is knocking;
• Secondly, check its work on a special stand.

If the stand shows that the problem is not in it, then it will be necessary to look for the cause in the engine. Moreover, for many modern machines the knock of hydraulic lifters when cold is normal. After all, cold oil has a huge viscosity and does not have time to fill the hydraulic compensator chamber, but after 30–50 seconds, when the oil warms up a little, the knock disappears. If the knock does not disappear after a minute, then it is necessary to look for its cause. For most cars, knocking on cold for 5-15 seconds is par for the course. After all, the oil from the chambers of the hydraulic compensators has leaked out, and the new cold oil hardly passes through the channels and jets.

If it is not possible to contact the workshop, and it is necessary to establish the cause of the knock of the hydraulic lifters, then first of all check the color and smell of the oil. If it is very dark or black, with bubbles, white foam or smells of burning, it is necessary not only to change it, but also to flush the engine 2-3 times with a special flushing oil. If there is white foam in the oil, check the engine for coolant leaks. After all, white foam (emulsion) is formed by water, antifreeze and antifreeze that have fallen into the oil. Remember that during flushing, you can not only load the engine, but even increase the speed. After flushing and installing a new oil filter, fill in the oil that is indicated in the instructions for the car and start the engine. Even if the oil is of a normal color and does not smell like burning, find a canister from it and compare the data indicated on the sticker with those described in the machine's service manual.

If the knock disappears, then the problem was in the oil or a dirty oil system. If the knock does not disappear, remove all hydraulic lifters and lay them in order so as not to be confused during the installation process. Disassemble and wash each compensator, check the operation of jets and valves, then install on the engine. If this does not help, then measure the oil pressure on a cold and hot engine and compare with the recommended values ​​\u200b\u200bfor your engine. If you do not have information about correct pressure oils, you do not know where to get them, or how to measure the oil pressure, then do not aggravate the situation with inept intervention and head to a car service.

Almost all automotive engines undergo a valve adjustment procedure. The procedure for adjusting valves is to set the gaps between the valve and the pusher. On engines where the valve clearance is manually adjusted, this must be done at regular intervals. This requires a certain skill, so the engineers came up with automatic gap adjustment. But this technology also has problems - this is the knock of hydraulic lifters, which will be discussed today.

Hydraulic compensator - is a device that allows you to automatically set the gap between the valve and the engine pusher. It is a metal cylinder in which there is a spring and a check valve.

The principle of operation is to change the length of the hydraulic compensator cylinder for the entire length of the gap in the timing. This device works from a reverse spring and oil pressure.

The hydraulic compensator is a non-tricky cylindrical device that consists of plungers, a reverse-acting valve and a spring.

The huge advantage of hydraulic lifters is that they automatically adjust valve clearances and save the car owner from this procedure. But besides the advantages, there are also disadvantages of this technology. The main one is a knock on a cold or hot in case of a malfunction.

How do hydraulic lifters sound?

The sound of hydraulic lifters resembles a clatter, very similar to the clatter of an loose chain. It comes from the cylinder head. From her top. The knock of the expansion joints can manifest itself in cold or hot, or it can always be present, depending on the wear of the expansion joints.

As we know, the operation of hydraulic lifters is directly related to oil. When the engine is cold, the oil simply has not yet entered the hydraulic lifters, so the engine may clatter characteristically for some time. But after a short time, if there are no other prerequisites, the knock will disappear.

This symptom is very clearly observed on domestic classic motors that are installed in the Niva of the last years of production. At one time, happy owners of these engines wrote a collective letter to the VAZ company and demanded a revocable company.

Causes of knocking hydraulic lifters

The main reasons for the knocking of hydraulics include two malfunctions:

1. mechanical parts of the hydraulic compensator
2. engine feed oil to hydraulic compensator

TO mechanical failures can be attributed:

1. Development and wear of the plunger spring. Most often it is natural wear, occurs due to the fact that the camshaft cams leave a working on the surface.
2. Clogged hydraulic lifter. Namely, the clogging of the valve that is responsible for the oil supply. As a result of this malfunction, the hydraulic compensator begins to stick.
3. Airing. Occurs when there is insufficient oil supply to the mechanism.
4. Soot and contamination of the main elements of the hydraulic compensator. Occurs when using low-quality oil or additives.

Malfunctions in the oil supply to the hydraulic compensator can be caused by:

• Oil filter failure.
• Low oil pressure
• Incorrect oil viscosity or wrong oil
• Overheating of the motor, as a result of which the oil loses its properties.

As mentioned earlier, the knock of hydraulic lifters is possible both on hot and cold.

When the engine is well warmed up, and there is a distinct knock of hydraulics, which means that there are problems with the oil. Perhaps the oil has already lost its properties and needs to be replaced. Or oil is filled in that does not fit according to the regulations for your motor. Also, the possibility of a clogged oil filter is not ruled out.

Changing the oil and oil filter can help in this case. If the knock on the hot remains, it is worth diagnosing other elements of the engine. Perhaps the problem is with them.

As for knocking on a cold one, then there is no need to worry, almost always this knock is not critical.

What to do if hydraulic lifters knock?

First of all, you need to determine which hydraulic compensator is knocking. For motorists, it is usually not difficult to determine which hydraulic compensator is out of order. Yes, you can do it yourself. It's simple.

To do this, remove the valve cover. You will also need a device called a phonendoscope.

A phonendoscope is a device with a long wire at the end and headphones.

If this device is not at hand, you can try using a stethoscope. I think you already understood the essence, you need to listen to where it knocks the most, so you can determine which hydraulic compensator is junk.

If a faulty hydraulic compensator is found, you can try to eliminate the knock by cleaning. To do this, it must be disassembled and washed in diesel fuel or kerosene. In some cases, this helps eliminate knocking. If not, then you will have to change. Their cost is not so great and it is better to do it as soon as possible, because otherwise the consequences can be sad.

How to check hydraulic lifters

Checking the hydraulic lifters yourself is quite simple. The device is not complex in its structure.

In order to find out the serviceability, you need to try to press on the inside of the hydraulic compensator (which is adjacent to the valve). If it easily misses, then the hydraulic compensator is faulty, if not, then everything is in order with it.

Is it possible to drive with knocking compensators?

As mentioned earlier, this malfunction cannot be started. Killed hydraulic lifters have a very negative impact on the entire drive of the gas distribution mechanism. Repair is worth it, not very cheap. Also, the knock of hydraulics leads to faster wear of all elements of the cylinder head.

Cons of hydraulic lifters

In addition to all the positive qualities of this wonderful technology, it has several significant disadvantages.

• Almost always there is a knock of hydraulic lifters on a cold engine.
• Hydraulic lifters do not work well at high speeds.

Changed hydraulic lifters and they still knock

The knock of new hydraulic compensators after replacement may not always be associated with their malfunction or marriage. As mentioned above, the operation of these devices depends on oil. If the new expansion joints are not filled with oil, they will tap for a while until they are full.

Outcome

Undoubtedly, the technology of using hydraulic lifters is very convenient. It is used by many different manufacturers in engines for both the budget and premium segments. But some still use manual valve adjustment technology, such as Honda. This is due to the fact that their motors are highly revving, and as we said earlier hydraulic compensators, there is also little space in the gas distribution mechanism, since in most cases proprietary Vtec technology is used there and there is very little space for hydraulic compensators.