Audi 2.7 TDI engine

Since 2004, Audi motorists have launched a new line of diesel engines, among which is the hero of today’s story Audi 2.7 TDI. Against the background of its predecessors, the motor turned out to be completely new, and it can be found exclusively on cars with four rings on the radiator grille.

The engine was the first for the brand to possess a timing chain, and the drive mechanisms are located on the rear side of the power unit, having four chains at once, one of which works on the oil pump.

Initially, a Common Rail fuel system was used for the diesel. The compressor is located between the cylinders, and there is provision for it to have controlled geometry via inlet-mounted vortex flaps.

The Audi 2.7 TDI engine was in production during 2004-2009, and was used exclusively on A4 and A6 sedans. Its closest relative with a volume of 3.0 liter received a longer life, becoming the basis for other heavy fuel engines for cars of other brands of Volkswagen AG concern, providing a longitudinal arrangement of the unit.

Technical characteristics of Audi BPP 2.7 TDI

General reliability

At once it is necessary to recognize, the engine at German engineers has turned out. High power, good economy, and most importantly reliability. The number of problems was many times less than in six-cylinder gasoline units. The first needs in minor repairs arise only by 200 thousand kilometers of mileage, and major breakdowns due to the fault of the engine itself are almost impossible. Except that there is one nuance – maintenance in the process of operation must be qualitative and timely, and its cost is very, very serious.

Two-mass flywheel

Most often, the diesel 2.7 TDI goes together with “mechanics”, which automatically provides for the presence of a dual-mass flywheel. In the original, its cost exceeds 3 thousand dollars, while the price tag of the analog is on average about 1.3 thousand dollars. On average, its service life is about 200 thousand kilometers, but with regular driving with premature transition to a higher gear, its wear can accelerate.

Intake system

The manifold provides for the possibility of controlling the geometry due to vortex flaps. At no load, they block up to 50% of the air supply. The axes for the flaps are common, and they are controlled by servos.

The mechanism was not the most successful, and on the first engines it took no more than a couple of years before errors appeared, which required replacement under warranty. In the future, the manifold was refined, and more than once, which allowed to partially solve the problem. Among the main problems: wear of rod joints, limiters, bushings on the axles, sticking of carbon deposits on the flaps with subsequent jamming, not the most reliable servo drives.

Axle rods are sold separately, and there are both original samples and analogs available, and in the latter case, in the repair kit are presented and flaps. For servo problems, the most common cause of failure is dust contamination. They will have to be disassembled to clean the microcircuits, and it will be necessary to act very carefully.

The cost of the original manifold is about 700 dollars, and analogs will cost about 250 dollars. Find on sale you can also find servo drives, its cost is about 180 dollars.

In some cases, car owners prefer to simply remove the flaps with the subsequent re-flashing of the electronic block.

Throttle control

The throttle valve in the intake system is characteristic of most diesel engines, it allows you to optimize the operation of the power unit when stopping and the re-entry of exhaust gases into the system. Flap gears are made of plastic, so they wear out rather quickly. They are replaced by analog metal parts, which are much more reliable and durable.

Turbine

The compressor used for the engine is characterized by excellent reliability, regardless of whether the unit is a product of Garrett or BorgWarner. On average, without frequent extreme modes, the turbocharger is able to go 300 thousand kilometers and even more.

EGR valve

EGR system elements of the V-shaped engine are located in the cylinder headland. The valve is controlled through a vacuum actuator. The damper regulates the direct supply of exhaust gases to the EGR or their redirection to the radiator.
On average, the survivability of the system is up to 200 thousand kilometers, sometimes more. After that, cooling leaks may occur, especially dangerous if antifreeze ends up in the turbine, putting it out of action. To exclude such problems, experts recommend removing EGR in advance, putting a plug.

Sometimes cracks appear in the pipelines, after which a characteristic exhaust odor appears in the underhood. The valve itself can sometimes wedge with the issuance of the corresponding error. Today, a significant part of Audi sedans with a 2.7 TDI engine is already deprived of the EGR system in principle, allowing to exclude possible problems with its reliability on cars with significant mileage. Masters have learned how to jam the system reliably, including updating the software.

Heat exchanger

The presence of a heat exchanger is necessary for pre-cooling of engine oil before it enters the filter. At a mileage of about 200 thousand kilometers, the gaskets on it begin to crack with the formation of oil leaks with the addition of antifreeze. The heat exchanger itself is located in the engine camber, but over time the volume of liquid is such that the oil-antifreeze mixture begins to flow down the body of the power unit.

The problem can be corrected by changing all the seals. For a set will have to pay about $ 40, and the most labor-intensive will be the process of freeing the block from oil contamination.

Jets

The supplier of piezoelectric nozzles is the famous German company Bosch. They work well, and even on not the most qualitative Russian diesel fuel they are able to serve up to 250 thousand kilometers. But only they are not adapted to repair from the word “not at all”, if a breakdown happens, you should immediately go to buy a new one. First of all, this applies to cases of piezocrystal wear, which cannot be avoided due to natural causes.

The risks of premature wear of nozzles are not excluded. It is expressed in atomizer malfunctions and increased diesel demand in the return. The first malfunction manifests itself in the form of increased smoke during engine operation, and in the second case, the lack of fuel affects the problems with starting the engine. Another sign of the need to pay attention to the state of piezo injectors is the presence of characteristic twitching when the engine is idling. Occasionally, when wearing atomizers of several injectors at once, fuel begins to drip directly into the cylinders, provoking the occurrence of hydrostroke with the ensuing consequences.

The cost of nozzles about 400 dollars, and their purchase in the branded packaging of the brand immediately increases the price, at least twice as expensive. The injectors themselves are easily monitored for condition using standard diagnostic equipment. The most objective results can be obtained by checking the injectors on a diesel stand. If used injectors are purchased, they also need bench testing before installation. Any injectors to be installed, including new, original ones, need to be prescribed. For this purpose, their personal codes are entered into the electronic system using the appropriate software. All old settings will be reset at this point. Ignoring the requirement will lead to the occurrence of detonation in the cylinders after a few hundred kilometers of mileage.

The fuel injection system

The main element of the fuel system of diesel cars is the fuel injector. In this case, it is the model CP1H3 from the company Bosch, which has reliability and good resistance to not the best quality fuel. Its plus is also good ability to repair. Worn fuel injectors with mileage over 300 thousand kilometers at low temperatures can leak fuel. Leaks appear under the plunger cover. On sale there are repair kits of seals that will need to be replaced. Cases of problems with pumping are isolated.

The pump drive works through a toothed belt, which has a service life of up to 250 thousand kilometers. Its rupture does not harm the engine, but due to the lack of fuel supply, the power unit will not be able to start.

Regulating valves

The fuel system of the engine provides for the presence of a pair of control valves. Directly on the fuel injector is located valve N290, which is responsible for fuel dosing, and on the fuel ramp there is a valve N276. There are no claims to the reliability of both, they are able to serve up to 300 thousand kilometers. Wear of the metering valve can cause instability of the rpm at idle, a drop in engine power and errors with insufficient pressure in the system. A broken valve located on the ramp will not allow the engine to start due to insufficient fuel pressure. Problems with the control valve can also be manifested by stopping the engine when the gas pedal is released.

In rare cases, fuel leaks appear under the valve, the fuel will accumulate in the socket, flowing into the return. At the same time, the electronics will show low pressure. In this case, the problem is with the condition of the fuel ramp, it will have to be replaced.

The limiting valve located on the return requires attention. The fuel return pipes are led into it, which are directed further into the fuel tank. For full operation of the fuel return system it is necessary to maintain a stable pressure of 10 bar. If the valve malfunctions and the inability to maintain pressure, problems with engine performance begin, insufficient pressure leads to the activation of emergency mode, under load the power drops sharply, there are difficulties with starting the engine. The valve is not sold separately, it will have to be bought in a set with return pipes, and it will cost about 240 dollars.

The timing chain

The timing drive is located on the rear side of the engine. Checking the condition of the chains is done on diagnostic equipment. In general, they are reliable, capable of passing up to 300 thousand kilometers. The check is carried out by the value of the deviation of the position of the “working surfaces of the cams” from the basic values. Initially, they are 680.4 ° and 610.4 °, respectively. In the presence of deviations within 3-4° there is a human-distinguishable noise, and in the case of increasing deviations up to 6° and above it is necessary to change the chain, its wear approaches critical values.

In some cases noise appears even if there is no significant wear. The cause of the problem is most often the hydraulic tensioners, which begin to jam and the calipers, worn out more than permissible values. The process of changing belts is labor-intensive and can be carried out only in the conditions of a full-fledged workshop, it will be necessary to raise the car on an elevator, after which the motor together with the box is lowered, their disconnection is carried out. Only after that it is possible to start dismantling the old chains. The only plus, the engine is in such a position that it is very convenient to service, so it is advisable to match the replacement of timing chains and other routine work, for example, replacement of gaskets under the valve covers, manifolds and so on.