DIY repair of automatic transmission Audi a6 c6

In detail: do-it-yourself repair of an automatic transmission Audi a6 c6 from a real master for the site my.housecope.com.

The device of an automatic transmission and its principle of operation are not known to everyone. But this unit, like other components of a car, tends to break down, and then the need for automatic transmission repair appears before the car owner. We will talk further about troubleshooting and repairing automatic transmissions in Audi A6 and Audi C5 cars.

An automatic transmission is an automatic transmission designed to provide automated gear selection based on driving conditions. This type of checkpoint has long been trying to adapt to the automotive markets of the former CIS countries. Recently, "automatic machines" have become more and more popular, today they are installed even on domestic cars.

In principle, the functioning and scheme of an automatic transmission is not much different from the "mechanics" with constant-clutch gears. In mechanical units, these gears are in constant mesh during vehicle operation. When changing speed, the corresponding gear is automatically locked on the driven pulley.

In the “automatic machine”, the gear pairs of gears are replaced by planetary gears, and the hydraulic and electronic control units of the unit are responsible for the choice of speed. Unlike "mechanics", when driving a car with automatic transmission, you will practically not feel jerks when switching speeds, since they are drowned out by the torque converter. It should also be noted that the automatic transmission uses an oil pump and an oil cooler. Indeed, during operation, the temperature of the unit can be very high, like a motor, or even higher. Therefore, "machines" are equipped with additional cooling systems.

Video (click to play).

When driving an Audi, gear shifting is carried out thanks to moving clutches. This occurs as a result of the disconnection and connection of the automatic transmission elements, namely the input and output pulleys and planetary components.

Disassembled automatic transmission

The work of the unit clutch consists in the constant compression of the annular pulleys themselves by the piston located in the drum. The oil goes through the hoses located in the drum, pulleys and on the body of the unit to the cylinder. Direct transmission of torque occurs during an increase in engine speed after a gear change. Control over these and many other processes in the operation of the unit is carried out by the control unit.

Audi A6 and C5 cars with automatic transmission, like other cars, are prone to breakdowns. Domestic roads do their own thing and over time, malfunctions appear in each unit. Below are the most common automatic transmission breakdowns in Audi A5 and C5 cars:

More complete information about breakdowns in the operation of the unit can be obtained with a complete computer diagnostics of the automatic transmission.

For self-repair of the automatic transmission Audi A6 or C5, you will need:

spanners;
flat and Phillips screwdrivers;
pliers.

CVTs are gaining more and more popularity among the varieties of gearboxes. So the carmaker Audi did not stand aside and installed variator gearboxes on the new A6 C6 models.

Each of the above listed elements can fail at any time. In today's article, we will analyze with you the main malfunctions of the Audi A6 variator, their causes of failure and methods of self-repair.

Earlier I already told you about how to replace the fuel filter Audi A6 with your own hands, so anyone interested can read this article by clicking on the link.

Most of the malfunctions in a CVT gearbox arise from improper operation, which I would refer to:

Violation of the frequency of replacement of the working fluid
Violation of the frequency of filter replacement
Using poor quality fluid
Aggressive driving style

In addition, there are other malfunctions that are determined using computer diagnostics. Each malfunction has its own diagnostic code. The codes determine:

malfunctions of input sensors (working fluid temperature sensor, speed sensors of the driving and driven pulleys, pressure sensors in the main line, pressure in the driving and driven pulleys);
malfunctions of the electronic control unit;
malfunctions of actuators (stepper motor, solenoid valves of pressure in the main line and pressure in the driven pulley, valves for locking the torque converter and control of the planetary gearbox).

The most common cause of variator malfunction begins with wear on the bearings of the cones, while a characteristic hum becomes audible. Bearing noise occurs due to the ingress of wear products on their working surfaces, as a result of which they become unusable. Special oil filters retain metal suspension for the time being.

The next reason that can cause problems with the variator is jerking and jerking of the vehicle, which occurs due to the seizure of the oil pump pressure relief valve. The same harmful wear products interfere with the normal operation of this unit, disrupting the stable pressure in the system.

Timely contacting a specialized workshop will help to avoid higher repair costs. Minor damage to tapered pulleys is removed by grinding, while the belt will most likely have to be replaced.

The rather rare malfunctions that precede the breakdown of the variator include the failure of the torque converter, as well as failures in the electronics caused by breakdowns of some elements of the control unit. However, this kind of malfunction occurs quite rarely and is not a regularity, but rather a factor of bad luck.

As I already noticed earlier, the most common variator failure is considered to be worn out bearings for cones. A sign of this problem is a prolonged hum, which manifests itself already when driving 50 thousand km. To change all bearings and their parts, the motorist will have to pay over 34,000 rubles. Such a malfunction most often occurs in Audi A6 C5 cars.

Loud noise of bearings, and then their slow destruction occur for the following reasons. First, the destruction of the working surfaces is facilitated by the ingress of various foreign metal bodies, such as wear products, on them.

The installed oil filter and magnet collecting metal powder cannot block access to the working surfaces of the variator for heavy foreign bodies. In this case, the bearing life will extend the reduction of the engine oil change time to 25 thousand km.

But that doesn't always help. There are cases when some CVTs work quietly for 100 thousand km, while others, under the same operating conditions, buzz even when driving 50 thousand km. High bearing noise is often caused by poor quality bearings, low accuracy and low load ratings.

When it comes to shortening oil change intervals, not all manufacturers share the same point of view. For example. During the warranty period (100 thousand km), Renault advises only to carry out periodic checks of the oil level and condition. At the Audi concern, the oil change must be done once every 75 thousand km.

Read also: DIY uaz 31512 gearbox repair

Doubt is a harmful thing, because haunts. therefore, due to the dust on the magnets, the box was thrown off again and disassembled to check everything. All clutches and steel are intact, there is no wear. So all the dust flew from the torque converter. We did not send it for repairs, because he was already there recently (the previous owner was renovating), and its general characteristics are positive:
- the reactor is blocked in the opposite direction,
- the turbine does not emit extraneous noise during rotation,
- the car runs normally at idle speed,
- the blocking works fine.
It was decided to rinse it with kerosene (while rotating the turbine with a K3 package), then blow it with air and spill it several times with oil to drive out the remaining kerosene. yeah. a lot of dirt. spilled several times - dirt comes out. while they poured kerosene and left - let it soak

Now about the box:
- Washers in place, no wear and tear.
- Bushings without wear.
- Pump surfaces without wear.
- Wear-free rubber edges of pistons and retainers.
The only doubt is caused by the o-rings of the pump hub and the K3 hub. somewhere I came across a review from Vlad-M that they sometimes flow (those from repair kits) and he only puts the cast-iron original. Therefore, my friend and I have plans to “slam” everything on the oil pump hub in order to check for the presence / absence of leaks

I could not find tolerances for K1. measured 1.7 mm from the pack to the stopper. a bit too much in my opinion. I also noticed that the stoppers in K1 and K2 are of the same diameter, but the thickness is different. difference 0.2 mm. Rearranged the stopper from K2 to K1. now K1 clearance is 1.5 mm, and K2 is 1.3 mm.

Prompted: ———————-
The gap in the package is 0.25 mm per clutch. It is not necessary to be small.
If the locking and pressure plates in K1, K2, K3 are not worn out, then the gap adjustment is not required. But B1 and B2 are regulated by the documentation.
The axial beating of all drums is also regulated.
Yes, the rings come across soft. But in your case, they have not yet been erased. ———————-

I found a little time - I added a photo as a whole in the report, and in particular on the tightness test:

Leak test:
It is necessary to inspect all surfaces to which the o-rings are adjacent. There should be no wear.
Oil pump hub, inside view:

Contact surface K1:

We also look at K2 - there is no wear.
We collect all this stuff on the hub of the oil pump and blow it under a pressure of about 6-8 atmospheres. We look, listen, if there are leaks, if the pressure holds. Small spills into adjacent channels are acceptable. For example, when we blow into K3, a small part of the air seeps into channel K1 and goes out:

SEPARATE BIG THANKS Vlad-M for correct hints

If you did not find information on your car, look at the cars built on the platform of your car.
With a high degree of probability, the information on repair and maintenance will be suitable for your car as well.

All documentation in English is marked (eng.), In German - (ger.)
For everyone who has a Volkswagen, hands and the desire to do something with them.
For all who has Volkswagen, hands and desire to do something by them.

As you know, a bad head does not give rest to his hands. A couple of months ago, oil began to drip from the engine-box junction. Moreover, the oil is clearly not from the engine, but transmission oil - both in color and smell. It dripped decently - after a week of parking in the garage, the dripping oil covered the bottom of the substituted basin:

For some reason, I was firmly convinced that this oil is from the automatic transmission box (and where else?) And most likely flows through the shaft oil seal and it is necessary to remove the box to replace the oil seal. Looking ahead, I will say that after removing it, it was found that the oil was flowing not from the box, but from the differential, which is located on the right side of the box and has its own oil (about 1 liter).

But since I took it off, I decided to write a small report on this topic. The box has the factory VAG code CRF, although in fact its real name is ZF 4HP-18. You can verify this by looking at the nameplate of the box.

All photos in the report are clickable, an enlarged image opens.

1) Removing the exhaust system

At first glance, everything is simple, but there is one ambush. If the glushak has not been removed for a long time and there are native studs, then when unscrewing the nuts, the studs will break off 100%, and then it will be very difficult to unscrew them without removing the head. To avoid this, there is probably only one way - to warm them up with gas welding. How to do this without damaging anything around - think for yourself, and when I was repairing the engine, I replaced the studs with M8 bolts with copper-plated nuts. [read more in “build AAH”]. Therefore, when removing the exhaust system, I did not have any difficulties - unscrew it from the exhaust manifold, from the box, and remove all the rubber bands on which the muffler and the entire system are suspended.

2) disconnect the axle shafts and cardan

- unscrew the protection (screen from the outlet) of the left CV joint - 3 bolts with an internal hexagon

- unscrew the axle shafts grenades. be sure to mark how they stood in order to screw in the same position:

the semiaxes are unscrewed with such an asterisk insert with a small step, size by 10:

- unscrew the cardan. be sure to mark as the cardan is bolted to the gearbox flange

after the operations, the car looked like this from below:

- turn off the battery
- unscrew the front protective casing of the poly V-belt

- with a 17 key, squeeze the tension roller to the right and remove the belt. We mark the direction of rotation in order to put it back in the same way

- unscrew the two mounting bolts of the generator. The lower one (key for 13) unscrewed without any problems at all, but with the upper bolt (for 16) there was a problem. The fact is that a nut is screwed on the back of the bolt and it, stsuko, scrolls along with the bolt. Therefore, hold the nut and unscrew the bolt with the other hand. Crawling to this nut with ordinary spanners is daunting, and possible only from below. You can make it easier if you remove the exhaust manifold tin screen, but I was too lazy and fucked for an hour with this nut. In general, it is not very convenient.
- unscrew the wires going to the back of the generator.

- the next problem is to take out the generator into the light of day. It can only be removed downward, and even then, for this I had to unscrew the front engine support, the cooling pipe, and pull off the hose going to the thermostat from this tube (the coolant is naturally already drained beforehand). It was also necessary to loosen the fastening of the aluminum tank of the air conditioning system (hell knows what it's called) and move it as far as possible to the face of the car. This was the only way to get the generator out of the car.

- in order not to climb there in the near future, I decided to sort out the generator, especially since it had already begun to whistle and creak. You can read about generator repair here.

The starter is bolted with two 16 bolts - one on the top, from the box side, and the second from the bottom, from the engine side. In the picture of the automatic transmission fasteners, these are bolts N1 (upper) and N9 (lower). The sequence of actions is as follows:

- be sure to disconnect the battery if you haven't disconnected it yet
- we first unscrew and lower the front part of the subframe, for which we unscrew two hefty bolts with a knob and a 16 head (in the photo the bolts have already been unscrewed):

- remove the air pipe from the DMRV sensor to the throttle valve
- unscrew and remove the air resonator installed on the throttle valve. before that, disconnect the plastic crankcase ventilation pipes going to both block heads. The pipes, stsuko, are very fragile!

- one bolt is unscrewed from below, screwed into the box from the side of the engine and starter. In the next photo, this is the leftmost N9 bolt:

- Access to the second bolt is carried out from under the hood, it is screwed from the side of the box into the starter. The upper bolt was unscrewed with a knob reinforced with a meter-long pipe. Not very convenient - the hood gets in the way, but I decided not to remove the hood. 🙂
- we take out the starter, the wires can not be unscrewed - just put the generator next to it on the floor, the length of the wires allows it.

A link on the topic about removing the alternator and starter on the audi-club forum.

5) unscrew the torque converter from the flywheel

The torque converter (in common parlance "donut") transmits torque from the engine to the automatic transmission. The bagel sits on the box shaft and is attached to the flywheel with three 15 bolts, which can only be unscrewed through the window of the removed starter. Before disconnecting the box from the engine, it is imperative to unscrew the bagel so that it remains on the box shaft when removed. The position of the bolt in the starter window is shown in the photo with arrows:

- we first mark the flywheel and the donut with paint in one place, so that later we can fasten it “as it was”. the bagel is marked through a special window on the box on the right side, access from under the hood
- for this operation, I needed an assistant who kept the crankshaft from rotating behind the pulley (with a 12-point head 24), while I unscrewed the bolts. The bolts sit very tightly, and you can't put a good knob in there, so it's better to unscrew it with a jerk, and you must hold the crankshaft very well.

6) unscrew the bolts of the automatic transmission to the engine

The box is attached to the engine with 10 bolts, most of which are "16", except for the N8 bolt (see figure), which is "13". Some of the bolts (upper) are screwed from the side of the box into the engine, and the lower 4, on the contrary, from the side of the engine into the box. Moreover, bolts N1 and N9 simultaneously attach the starter.

bolts 6, 6, 8 and 9 are accessible only from the bottom of the machine (part has already been unscrewed):

It is very inconvenient to unscrew the N7 bolt from under the hood - you can't get in there with a pipe or a knob, since the left steering rod gets in the way, so I unscrewed it from the bottom, from the pit, with a spanner wrench. The rest of the bolts are easily accessible from above, from under the hood and can be easily unscrewed with a crank with a meter (or maybe half a meter) pipe put on it.

7) unscrew the box from the pillows

Before performing this operation, drain the oil, I got about 4 liters. The drain plug with an internal hexagon rusted specifically and it was possible to break it only by hammering an asterisk into the torn hexagon.

We put something under the box, for example, wooden boards, so that after unscrewing it from the supports, it does not crash down on your head. We unscrew one bolt with an internal hexagon on each pillow. On the left, everything can be unscrewed without problems, but on the right, access is very inconvenient - it is impossible to crawl with a ratchet, a knob, or a key. I used a hexagonal insert and twisted it with a 10 "spanner wrench.

After that, the rear part of the box is lowered onto the stands, the front part needs a little help, gently squeeze it from the engine with a pry bar.

To completely remove or move the box, you still need to disconnect the gear shift rod. But while the left support of the box is screwed on, it is very difficult to crawl there, so we unscrew the left support and with a key or head “10 ″ unscrew the nut securing the switch rod.

By lowering and moving the box from the engine, you can remove the donut from the box shaft:

This completes the removal of the box.It turned out that I took it off in vain, as the oil flowed through the internal differential seal - there is separate oil from the automatic transmission, but I gained invaluable experience in removing the box. Finally, a couple more photos.

Here it is, the disgusting oil seal, because of which so much work has been done:

Oil seal number 0734 319 339 is not in any catalog. It is also unclear from ETKE what number this oil seal has. Through the automatic transmission, we managed to find out the new number of this oil seal according to the ZF catalog - 0750-111-193

Along the way, I will solve the following problems:

- the oil seal of the “torsen” shank leaks (where the universal joint is screwed on)
- the seal is leaking on the electrical connector of the box control
- the torso is covered in oil, which means that the oil inside is already two times less than it should be
- the left cushion of the box is torn
- it is necessary to change the oil in the automatic transmission. mileage since the last replacement has already amounted to almost 70 thousand.
- the oil drained from the box is clean, without signs of any shavings or impurities. this makes me happy.
- all the time of operation, I was haunted by strong vibration on the body, when I started off with the wheels turned out, or made a turn at low speed. The time has come to cure this business - at the conference, Automotive News read the GMA advice to pour SAF XJ75W140 oil into the torso - synthetics specifically for the differentials of all-wheel drive cars. It seems like someone tried it, they say it helps.