It is common that when starting the car you hear a strange noise coming from the engine. This sound may stop after a few seconds, but sometimes it lasts longer. Even in the worst situations it never goes away. If any of these apply to you, one of the most common causes is hydraulic tappets. Also called dumpers.
When starting the car, the noise produced by the tappets is usually a knocking caused by lack of lubrication. Something very frequent when the engine is cold, and that gets worse if it has been left standing for several weeks (days in some models). The lubricant has mostly drained to the sump and the oil pump still hasn't sent it all the way to the top of the engine.
Regardless of the model you have, the noise generated by the hydraulic tappets it is not normal if it lasts more than a few seconds. Once the engine warms up a bit and the tappets fill with oil, the noise should go away, and if it doesn't, there are a number of issues that could be causing the problem.
Why do hydraulic tappets sound?
There is a large number of reasons why the hydraulic tappets of an engine can make noise. we are going to describe you the most common ordered by the ease with which they are checked. Because it will not be the same to review the engine oil, than send it to a workshop to repair, or even get down to work yourself, if you are a mechanics enthusiast.
Lack of oil or excess oil
The first thing to do is check the oil level to leave it at the optimal level. Only then can we rule out that it is an excess or lack of oil in the engine, which can alter the operation of the lubrication system in such a way that it generates noise. The steps to follow are:
- Put the car in a horizontal position to prevent false oil measurement. A slope, even a slight one, will cause the oil to accumulate on one side, causing it not to mark the correct height on the dipstick.
- Wait until the engine is cold. This will have passed the necessary time for the lubricant to slide down to the crankcase. Otherwise it will appear that the engine has less oil than it actually does.
- Pull out the dipstick from the engine, clean it with a piece of paper or cloth and put it back. Be careful not to leave lint, pieces of paper or fabric that can get into the motor. Any impurities you introduce can be detrimental to the engine.
- Pull the dipstick back out and see how far the oil has stained.. It should be between the two minimum and maximum marks that the manufacturer has engraved on it. If the oil is very new, and you cannot see well how far it goes, stain the cloth or paper with it. It will be much easier to see on a white background.
- If the oil level is by debajo del minimo, top up a little by pouring it through the oil plug.
- Nap above the maximum You will have to remove some oil until it is between the appropriate levels. What you can do through the crankcase screw, with a suction pump or taking it to the workshop.
- If you want to know more about measuring oil and how to add or remove it from the engine, see the article on how to check the oil level. In it we tell you how to do it correctly, in addition to explaining other methods that exist when the engine does not have an oil dipstick.
very used oil
Another reason why hydraulic tappets can generate this noise is that the oil is already in bad condition. Lubricants have a number of maximum kilometers or with a time frame in which they maintain their properties. If these limits are exceeded, their degradation will be such that they will not be able to fulfill their task and the tappets will sound.
To this we must add that the rest of the pieces the motor they will also not have adequate lubrication. This will cause the consequent premature wear of many moving parts and the drastic reduction of the useful life of the engine. Take a look at the article 130.000 kilometers without changing the oil, to find out what happens to a maintenance-free engine.
wrong oil
In this case, the factor that can most affect the tappets is the density of the oil is not correct. In other words, if, for example, your engine is a 1.9 TDI and according to the manufacturer your model should have 15W40 oil, you should not put any other. The lubrication will not be adequate and the engine will be seriously damaged. For example, if the oil is too fluid, the oil will drain into the crankcase too soon and too much, leaving the top unprotected, which is where the hydraulic tappets are.
To this should be added many other problems that should not go unnoticed. The most common and visible is that the engine burns too much oil. Something that happens because more of it is filtered to the combustion chambers through piston rings. Which is noticeable because the color of the smoke coming out of the exhaust pipe has a slightly bluish color.
Si the oil is too thick, you will also have lubrication problems because will not arrive Correctly to all parts the motor. Probably including hydraulic tappets. Again, other problems would also have to be perceived in the engine, which would greatly shorten its useful life. If you are not sure which oil to use, visit our article on Motor oil.
Too little or too much oil pressure
Again we are facing a cause related to engine lubrication. Oil pressure is an unknown factor for many neophytes in car mechanics. Above all, because few cars include an indicator that shows what level you are at at all times. Only some models with a sporty approach, designed so that a lot is demanded of them, have it in their instrumentation.
If the oil pressure is inadequate, there can be two cases with different causes:
- little pressure: occurs when the oil is very worn, has a very low density or the oil pump It's damaged. If, as we have indicated before, you have already verified that the oil is in good condition and is the correct type, it is most likely the pump.
- a lot of pressure: this is usually due to the fact that the spring of the pump that regulates the pressure is obstructed or in poor condition. It would have to be cleaned or replaced. An operation for which it is advisable to take the car to the workshop, unless you have advanced mechanical knowledge and the appropriate tools.
Stuck rocker arm or hydraulic tappet
Lastly, tappets can stick if left varnish residue between the piston and the body of the tappet. In this case, we can solve this problem by adding an oil additive to the engine. They can also be clogged ducts of the tappet itself because many impurities have reached them.
Damaged hydraulic tappet
Lastly, the engine lifters may have worn. damaged causing noise to be heard. If so, the less you use the engine, the better, because it can lead to major breakdowns if you continue to drive with it. The most common is that the camshaft gradually wear off. If you can, call a tow truck and have the car taken to the shop. This will minimize damage to your engine.
Additives to reduce friction and eliminate tappet noise
There are several additives added to engine oil that their developers claim to eliminate or minimize noise from hydraulic tappets or tappets. For example, those of liquid moli, although there are more brands that make similar products. Their function is to further reduce the friction that may be caused in the engine, so they can be effective for the noise of the tappets if the problem is not the deterioration of the part.
Anyway, we recommend that before any additive, you make sure that the lubrication system of your engine is property. That is, oil in good condition and of the correct type, oil pump 100% operational and the rest of the indications in this article. Otherwise you would be wasting money.
If we see that the noise persists, The most advisable thing would be to take the car to the workshop to carry out the relevant checks. Apart from the lack of lubrication, there are other reasons why the tappets of our car can fail and produce noise.
For instance, if there is dirt in the check valve, can be produced internal leaks in the hydraulic tappet. It can also happen that there is abnormal wear between the plunger and the tappet itself, producing excessive leakage that causes noise in the tappet. A mechanic can fix these problems.
Images 3, 5 and 7 – Nenad Stojkovic, Adrian Sampson, Mark Morgan
