Valve clearance hydraulic tappet does all the dirty work for us to adjust the clearance between the valve and the camshaft (pusher, rocker). Nevertheless, with a careless attitude to the engine, the sound of hydraulic lifters can really ruin your mood and throw up problems. Is it possible to ride on knocking pushers, how to get rid of knocking, and what to do to increase the resource, repair or buy hydraulic lifters, we will consider these subtleties right now.
Hydraulic lifters are rattling. Causes and consequences
Clicking, clanging, tapping pushers are only the first signal that something is not right with the engine. The knock of the hydraulic lifters is like a litmus test of the state of the lubrication system, and of the entire engine. Visually, we cannot judge the degree of oil wear or the cleanliness of the oil channels.
The instruments on the panel will also not say anything – the pressure and level are in order, which means everything is fine. A hydraulic compensator of any design is a finely tuned plunger device that will respond to any negative changes in the lubrication system.
Is it possible to drive with faulty hydraulic tappets
[stextbox id=’info’]Highly undesirable. We understand that the sound of lifters indicates incorrect operation of the gas distribution mechanism. And this means that the valve timing is not set up as expected.[/stextbox]
Driving with the sound of hydraulic lifters will give you:
- high fuel consumption;
- severe loss of power;
- possible overheating of the engine;
- if tightened with repairs, the valves or the piston crown will easily burn out.
When a knock appears, it is advisable to diagnose and repair it as soon as possible.
Knocking hydraulic lifters on a cold engine
The sound of hydraulic lifters on a warm and cold engine can indicate various malfunctions and issues. However, there are no such troubles that could not be corrected. Cold hydraulic tappets can clatter for a number of simple reasons:
- The issue is with the hydraulic lifter itself. Tappets are a thin device that has their own resource, and if they have passed more than 50-70 thousand km, it will most likely be necessary to replace the hydraulic lifters. Nevertheless, there is a possibility that the tappets are simply coked. In this case, it can be washed, inspected, and made a conclusion about the condition. Treatment without disassembling the head in this case is impossible.
- Oil problem. If we know that the oil resource is already running out, after the replacement the car has traveled more than 5-7 thousand, the knock of the hydraulic lifters will be caused by oil wear. It loses its characteristics and only begins to harm the engine – it loses viscosity, clogs oil channels, and blocks the oil filter. The lifters also suffer from dirty old oil, so it needs to be changed urgently before we ruin the engine.
- Bypass valve of the hydraulic lifter. After the engine is stopped, the pumped oil must remain in the hydraulic tappet housing. It is held by a ball valve so that at the next start the plunger does not wait for a new portion of oil but immediately gets to work. Therefore, the knock of the hydraulic lifter on a cold one, despite the fact that it does not knock on a hot one, may indicate a clogged or worn hydraulic lifter valve. The solution to the issue is pumping the tappet or replacing it if it fails.
- Clogged, coked oil channels. Both in the head of the block and in the tappets itself. The optimal solution is mechanical cleaning of the channels with the disassembly of the blockhead. Some drivers use all kinds of chemicals, there are oil additives that should restore the efficiency of hydraulics. But miracles do not happen, and with an additive, at best, we will delay the inevitable cleaning of the channels of the lifters or the head itself.
- The type and viscosity of the oil do not correspond to the operating conditions of the engine. It may be too viscous or too liquid. In both cases, the hydraulic lifters will react first.
- A clogged oil filter. It changes along with the oil, so after replacing both, the cold knock may stop.
Knock of hydraulic lifters on a hot engine
- The oil has exhausted its resource. As in the case of knocking on a cold one, we change the oil along with the filter if, after the change, the mileage was 5-7 thousand km.
- Tappet valves are clogged. In this case, there may be no knocking on a cold one, but when the body, plunger and pusher valve are heated and expanded, the oil may not enter the body at a certain warm-up temperature. The way out is cleaning the hydraulic lifters.
- Oil level. If the oil level is below normal, the oil pump will not physically be able to deliver it to the furthest points of the lubrication system. True, this should be signaled by a pressure or level control lamp. In any case, check the oil level and bring it to normal.
- Pressure. The oil pump is not able to develop the required oil pressure. As in the previous case, this threatens to air the compensators. Check oil level and pressure. It is possible that the oil pump is worn out, or the pressure reducing valve of the oil pump is out of order, the intake screen is clogged.
- Mechanical damage to the hydraulic lifter or its installation site. This can only be found after removing the valve cover and carefully inspecting the gas distribution mechanism.
New hydraulic lifter knocking
It happens that after a complete replacement of lifters, a knock will be heard during the first engine starts. This is quite normal since the tappets need to get used. Nevertheless, the knock should disappear after 100-200 km of run.
If new wetsuits keep rattling, it’s not their fault. That is precisely why it is very important to be able to buy hydraulic lifters with a guarantee, from a good manufacturer, and from a reliable seller.
In addition, the knock of new hydraulic lifters just bought, may be caused by their incorrect installation. For example, we made a mistake and did not sink the hydraulic to the end into the well, the oil channel of the blockhead did not coincide with the inlet of the compensator. As a result, the oil did not get into the body, the lifter cannot physically work. As an option, when new tappets knock, clogged oil channels, the oil does not get access to the lifters.
Diagnostics. How to detect a faulty hydraulic lifter, how to check
To diagnose the hydraulic tappet, you do not need to go to the service station and pay extra money. The signs of its malfunction are so obvious that we will determine them ourselves. Before checking the hydraulic lifter, we find a probe or a set of probes with a thickness of 0.01-0.5 mm.
We remove the valve cover and find any open timing valve – the camshaft cam should look up. We insert the probe between the lower part of the cam and the lifters, if the gap is more than 0.1 mm, the tappet does not work, it needs to be pumped, repaired, or replaced.
More precisely, you can check the hydraulic lifter removed from the head. If we manage to push the tappet with our hands, it will fail and squeeze out, there is a malfunction. In this case, we will change the lifter or try to restore it, it all depends on the design of a particular tappet.
Restoration, repair of hydraulic tappet
Not every lifter is repairable, but sometimes replacement can be delayed. This is especially true in cases where it is not possible to buy a suitable type of tappet from the catalog. There are at least three ways to restore the pusher:
- Washing with a special composition. The best composition for flushing hydraulic lifters is Liqui Moly Hydro-Stossel-Additiv. Its price is about $12, it will help flush the channels of the tappet, the oil channels of the blockhead. It is used as a flushing of the lubrication system with both new oil and old oil (preferably): pour 300 ml (for 6 liters of oil) Liqui Moly Hydro-Stossel-Additiv into the engine, after a run of 700-1000 km, drain and change the oil and filter. If the matter is in the coking of channels, it helps in 90% of cases.
- Flushing the lubrication system by the standard method when changing the oil and filter. Not everyone likes flushing compounds, so whether or not to use this method is a matter of opinion.
- Mechanical cleaning works best. Yes, you will have to remove and disassemble, clean and rinse the hydraulic lifters, but we will be 100% sure of the result and will not poison the engine with chemicals.
Keep track of the condition of the hydraulic lifters and your engine will work for more than one hundred thousand mileage without problems.