Replacing the BMW N20 timing: diagnostics and recommendations

by | Aug 20, 2022 | Articles

Every owner of the BMW N20 engine knows how important it is to monitor the condition of the timing drive, i.e. the timing chain. It is recommended to change it every 100,000 kilometers along with a tensioner, a sedative, a water pump and stars.

Despite the fact that the time after which the new mechanism should be installed as indicated by the BMW in the operating instructions, one should not fully rely on this regulation. Otherwise, you can miss the point, and then the restoration of the engine will cost a large amount. In our article today, we’ll look at what symptoms indicate that a replacement for the BMW N20 timing is required, as well as how to perform it.

Why you need a timing belt replacement in the BMW N20

First of all, we will consider what a gas distribution mechanism chain is and why its replacement is necessary. The design of this element, necessary to synchronize the operation of pistons, valves and the ignition system, is simple.

The chain is located on the stars of the crankshaft and camshaft, while it simultaneously drives the water pump.

To ensure that the chain is properly tensioned, an automatic tensioner is installed. If the circuit breaks, the inlet and outlet valves will meet with the pistons, which will lead to a major overhaul of the engine. Until repairs are carried out, the vehicle cannot be operated.

The BMW N20 timing belt should be replaced when the chain is stretched. In this case, it is worth considering not only the period specified in the manual, but also the conditions in which the machine is operated.

Reasons to replace the timing chain in the BMW N20

The timing chain of the BMW N20 is located in the motor, which means that it does not experience external influences, it operates almost silently. However, this feature leads to its frequent breakdowns. The fact is that its performance is affected by how much and which engine oil is filled, how often it is changed. If there is insufficient lubrication, you will have to replace the BMW N20 timing belt, because the part will wear out.

Reasons to replace the timing chain in the BMW N20

The BMW N20 timing chain is replaced because it wears out quickly for the following reasons:

  • The tensioner has deteriorated, as a result, the timing chain of the BMW N20 does not stretch well, slips, and the valve timing is disturbed.
  • The chain tensioner is malfunctioning due to low oil pressure. The chain is not tight enough, slips through the teeth.
    Camshaft gears become unusable, as a result the chain slips;
  • A replacement for the BMW N20 timing chain will be necessary if low-quality oil is poured into the engine or it does not fit this engine or rarely changes.
  • The detail is old: the articulated joints of the links wear out over time, the chain becomes stretched.
  • The chain may fail if the machine is operated at full load or the speed rises sharply.
  • Repair and maintenance of the gas distribution mechanism were carried out by an inexperienced master.

Signs that it is time to replace the timing in the BMW N20

The main reason that leads to the frequent replacement of the BMW N20 timing belt is that it is difficult to get to the part. Therefore, it is not easy to detect a malfunction of the mechanism and prevent the timing drive from breaking. Compared to the belt of mounted units, this part is hidden under the covers. In order to inspect it, you will have to disassemble the motor, and not every driver will be able to carry out this procedure.

Timing Replacement in the BMW N20

On the BMW N20 engine, timing should be replaced every 100,000 kilometers. The automaker indicates this period, because the oil temperature is high and the plastic guides deteriorate quickly. To prevent engine damage, the BMW N20 timing chain should be replaced when mileage has not reached 100,000 kilometers. In addition, on the engines of the first BMW N20 series there was a malfunction of the oil pump drive. Gears and chain for a short time became unusable, as if they were not hardened. How to determine if a pump circuit is worn out? A specific rumble at high speeds will appear.

How to determine that a part is worn, defective, or counterfeit when replacing a BMW N20 timing belt:

  • damage and rags on the inner or outer edge are visible;
  • the smooth side is frayed, there are burns on it;
  • the teeth are frayed, clipped;
  • the outer and inner sides of the belt cracked.

If you find one of the above signs, a BMW N20 timing belt replacement cannot be avoided. But besides the symptoms that are visible to the naked eye, such as cracks and tears, there are implicit signs of an imminent breakdown. Next, we describe the most common of them.

  • Big belt age
    When to replace the BMW N20 timing does depend on the mileage of the car. If the car skated tens of thousands of kilometers, it is necessary to replace the part. But you need to consider how old the belt is. After all, after 5 years, it becomes inelastic, cracks appear, and it does not matter how much you travel by car.
    If you rarely operate a car, you must regularly check the condition of the timing chain.
    After purchasing a used BMW N20, be sure to check the timing chain. Perhaps the former owner of the car installed low-quality parts, the life of which has long come to an end.
  • Uncertain engine starting and power loss
    When the timing chain of the BMW N20 wears out or its tension is insufficient, it is necessary to replace the element, because it starts to skip one or more teeth. As a result, the ignition starts to work incorrectly, ignition of the fuel-air mixture does not occur on time. How to determine what the problem is? The engine starts uncertainly, there are failures in traction, the motor vibrates. The machine will be operated in suboptimal mode. The ride will become uncomfortable, in addition, expensive repairs may be required.
  • Exhaust pipe smoke
    Due to the fact that the replacement of the BMW N20 timing belt was not completed on time, the catalytic converter may melt and collapse. The reason is that the fuel does not completely burn out in the engine. Due to the fact that the ignition is knocked down, fuel enters through the valves into the exhaust system. As a result, the temperature in it rises and the cells sinter. To determine this malfunction, you should listen to the operation of the exhaust system. You will hear clapping sounds, exhaust fumes may be black. All this suggests that the mixture is re-enriched and does not completely burn out. To fix the breakdown, replace the BMW N20 timing belt.
  • Ticking sound from the motor
    If the timing replacement for the BMW N20 was not completed in a timely manner, the chain stretches.
    All this leads to the appearance of extraneous sounds: when the engine is started, you can hear ticking, shuffling, clicking, and the sound will come from under the casing of the system. Extraneous sounds appear from time to time depending on the engine speed. With their increase, the sound amplifies. Of course, such symptoms can occur for other reasons. For example, due to the fact that the bearing of the water pump wedges. Postponing repairs is not recommended. In order to detect and eliminate the breakdown, you will have to dismantle the timing belt cover of the BMW N20.
  • Leakage from the timing case
    The next sign that the BMW N20 is to be replaced is oil drips and antifreeze leaks in the drive area. Grease begins to ooze from under the crankshaft oil seal that has become unusable, antifreeze from unpressurized joints or from under the pump pulley. In both situations, it is necessary to replace the BMW N20 timing belt, because the chain will wear out faster, and may begin to skip on the stars.
  • The engine does not start, the starter spins idle
    Do not bring the timing to the point where it will be too late to replace. After all, if you do not carry out this procedure in a timely manner, the chain will break. You will immediately understand if this happens. During scrolling, the starter will work fine, even better than always. However, there will be no fuel pickup idle, it will not ignite in the cylinders. This suggests that there is no compression due to the fact that there was a bend of valves that met with the pistons.There are two ways out of this situation: throw out the engine and install another one or restore the damaged motor in the service center. No matter what decision you make, in any case you have to spend a large amount.

How to control the condition of the timing chain

To replace the BMW N20 timing chain in time and keep the engine, follow these tips:

  • If the warranty period after buying a car has not yet expired, you don’t have to worry about the condition of the timing chain. However, the automaker provides a small guarantee on the gaskets. For example, the camshaft oil seal will leak, the lubricant will fall onto the chain, which will become unusable because of this. As a result, the owner of a car under warranty will have to make expensive repairs.
  • Do not forget that the factory timing chain on the BMW N20 will last longer than the parts installed after. The fact is that the chain goes along the teeth of the stars, the wear of which is small. If you change the second or third chain, it is necessary to carefully monitor the state of the teeth of the star – whether they have come off.
  • As soon as you replace the BMW N20 timing belt, you should conduct a visual inspection of the mechanism after 2-3 trips. Only in this way will you be able to understand that the part is not fake, and the running-in is normal, the tension is sufficient. It is worth listening to the sound of the chain.
  • If the car was driving through a deep puddle, stream or mud, the chain should be inspected. In this case, clay can penetrate under the protective casing, because it still allows water to pass through.

How is the timing chain replaced in the BMW N20

The timing replacement technology on the BMW N20 is exactly the same as on the first N-series engines. This work is quite simple, but special tools will be needed, without them, replacing the timing motor of the BMW N20 will not work.

The sequence for replacing the BMW N20 timing chain is as follows:

  • First of all, drain the engine oil;
  • then dismantle the motor pan, remove the gasket, then install a new one in its place. Remove also the valve cover, there will also be a gasket in it, we also replace it;
  • then disassemble the timing system;
  • wash and clean the motor of soot;
  • Mount the new timing chain on the BMW N20;
  • reassemble in the reverse order; do not forget about the new gaskets for the pan and valve cover.

Note! It is also necessary to replace the bolts, the front crankshaft oil seal, the timing gear star.

Common mistakes made while replacing the timing chain in the BMW N20

To prevent the chain from stretching, slipping gears through the teeth, and breaking, the BMW N20 timing chain must be replaced in accordance with the manufacturer’s recommendations.

When replacing the BMW N20 timing chain, follow these guidelines to avoid mistakes:

  • Do not measure the circuit when the motor is running;
  • its length should be measured by scrolling the crankshaft with your hands;
  • while measuring the length, the crankshaft can only be turned in the direction of travel;
  • chain length should be determined using a special tool;
  • crankshaft can be turned only after the chain tensioner is installed;
  • To remove and mount the chains, you need to use special equipment;
  • during removal and installation of the circuit, loose elements may get into the motor so that this does not happen, cover the cylinder head with a clean rag;
  • when installing the chain, tighten the bolts with a certain moment;
  • The replacement of the BMW N20 timing chain is accompanied by the installation of new camshaft sprockets, tensioner rails, and caliper. Be sure to read the repair instructions;
  • After replacing the BMW N20 timing chain, add new oil to the engine.

The opinion of car owners on replacing the timing chain in the BMW N20

  1. Plastic ages in 5 years
    “The replacement of the BMW N20 timing chain is required due to the fact that the plastic guides become unusable after 5 years. No matter what the mileage will be during this time – 200,000 km or 50,000 km, the condition of the part will be deplorable. ”
  2. Color Change – Problem Indicator
    “The replacement of the timing of the BMW N20 was done by hand, the mileage was 140,000 km. There was a whistle of the oil pump circuit. I did not find any debris in the pallet, the chain was in working order, the tensioner was a new sample. For this reason, I decided that the chains were changed by the previous owner of the car, but the dampers were brown. Completed the replacement of both chains, as well as plastic dampers, tensioners, sprockets on the crankshaft. There are no extraneous sounds. ”
  3. Better to wait and change everything
    “I believe that replacing the BMW N20 timing belt should only be done when there are signs of malfunction. For example, extraneous sounds, buzzing. I’m afraid to get into the motor, because the master may be inexperienced. I will wait, when a howl appears, then I will do a replacement right away. I think that you just don’t need to change the chains, because after assembly the howl can remain, and you will have to disassemble the motor again to change the oil pump and shafts. ”
  4. The quieter you go, the further you’ll get
    “A specialist in a car service said that if you drive aggressively, constantly squeeze gas, then replacing the BMW N20 timing belt will be required after 40 00 kilometers, because the chain will be stretched and the damper will crumble, the oil pump will become unusable. And if you operate the car carefully, then after 130,000 km, replacement will not be needed. ”
  5. Change on time so as not to fall
    “Departed for three years, dashed off 120,000 kilometers. He replaced the BMW N20 timing belt, then it turned out that all the parts were in working order, the chain was extended by 0.1 cm, the oil pump chain was generally ideal, the tensioner spring sagged by 0.3 cm, this is not a problem either. The plastic did not crumble, but was sullen and darkened. Why did the replacement? He studied the forums and was afraid to ride the old chain. Filled with new engine oil every 8,000-9,000 km, warranty Castrol, after 80,000 km I started using Motul, I’m not standing in traffic jams. After replacing the timing, the BMW N20 skated 1,000 km, there are no problems with the car. ”


Drawing from extensive expertise in the used car parts industry, Craig Sandeman has established himself as a trusted authority in automotive repair. He possesses a deep knowledge of the challenges encountered by individuals seeking reliable car parts, making him a highly sought-after expert in this field.


Potential issues, causes, and solutions have been identified in the above article based on the experiences of car owners and repairers, as well as web materials such as forum blogs and technical support bulletins. This data is supplied exclusively for the purpose of reference. Only appropriately qualified persons should perform repairs and/or changes on your vehicles.

While it’s important to keep in mind, it’s also important to note that the amount of times anything is mentioned here should not be seen as a sign of its reliability or frequency. Various owners, driving in different ways, and caring for their vehicles in distinct ways will cause two identical vehicles to perform differently.

As previously said, this material is supplied primarily for reference reasons; nonetheless, we hope that by doing so, we will be able to supply you with essential knowledge that will allow you to make informed decisions whenever you encounter any of the aforementioned setbacks.


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