Photo 1: This is no longer enough information to order parts.
To say that Volkswagen and Audi Group (sometimes mistakenly
referred to as VAG) is a large part of the automotive scene worldwide is a
gross understatement. From basic transportation to record-setting performance
cars, VAG is a recognized leader in innovation and cutting-edge technology. A
broad spectrum of models has put a huge number (millions) of VAG models on the
road in North America, and these cars will provide many years of potential
repair and service opportunities. Getting to know the various models, repair
techniques and a few shortcuts will help make repairs more routine and
profitable.
Photo 2: Look for a tag like this for engine information; engine codes can be found elsewhere as well.
In this article, I’ll focus on common repairs we see on a
daily basis. The series of cars covered in this article will be the VW Passat
and Audi A4 and A6 line from 1998 to 2004, as well as the Audi TT and
transverse engine VW models. These cars are all very similar in design and
equipment, and most repairs are consistent between models.
Photo 3: Complete information on equipment can be found on the data label near the spare tire well.
Increasing numbers of distinct models, multiple
manufacturing plants and countries of origin, and constantly changing
technology make vehicle identification ever more important (see Photo 1),
especially as it relates to obtaining the proper parts and data needed to
complete repairs.
Most VAG cars will have engine and transmission ID tags that
are easy to access and read (see Photo 2). With many models, having the VIN is
all that’s needed to determine the OEM equipment, but use the vehicle data
plate for more concise information (see Photo 3).
As always, this article should not be considered a
replacement for obtaining the proper, model-specific information for the model
being serviced. Repair information is readily available in print form for all
models and on-line tech assistance is available from many sources. However, be
careful when pulling information from owner forums, as I’ve found a number of
inconsistent recommendations that can be more harmful than helpful.
TRANSMISSION SERVICE
Photo 4: Pan damage deserves a closer look.
Automatic transaxle dipsticks and fill tubes disappeared
from most VAG models in the late 1990s and, on most models, remotely mounted
coolers with accessible lines went away even earlier. On models built after
1998, the procedure to change, add or refill a transaxle requires some
additional steps to successfully complete a service.
Failing to get the fluid level in the transmission correct
will cause shifting problems, codes to set and possible damage. There’s a very
delicate balance between too much and too little fluid, depending on
temperature and the fill status of the torque converter. This process requires
a scan tool or other means of monitoring transmission temperature, a means to
fill the transmission while it’s elevated and running, and careful planning to
complete the steps before the transmission temp climbs too high.
Photo 5: Check fluid level here by removing the plug. If no fluid runs out when cold, the transmission is probably not full.
Each model year and transmission has a specific procedure,
although most are based on the same principle. Failing to properly go through
the refill steps will cause shifting problems and potential damage. In short:
If the transmission has no fault codes, take the time to explain and recommend
a transmission service and refill as a first step. Bear in mind that special
fluid, tools and equipment will be needed, so be prepared before you pull that
plug or give an estimate of costs.
Photo 6: Transmission components are vulnerable; even minor curb damage can cause problems.
On the car used in this example (an Audi TT, based on the
New Beetle/Golf platform), the dent in the pan (see Photo 4) appeared to be
large enough that there could be internal damage. I’ve seen on other cars that
this type of impact has dislodged the filter or damaged the valve body or
solenoids. Though that was not the case here, it was a reasonable assumption
and needed to be investigated.
When the check plug (see Photo 5) was pulled with
the transmission cold, there were about three drops of fluid that came out, but
there should have been more. Even with level checking and drain removed, there
was probably only about a quart of fluid in the pan. I don’t know why, as there
were no significant leaks or evidence of previous service. But since this was a
new car for the customer, there was no service history available.
Photo 7: VAG factory fill bottle.
The pan was pulled and a basic inspection revealed no
internal damage (see Photo 6), discolored, but not burnt, fluid and
a filter that showed very few impurities. A point worth noting here is that the
filter is actually a metal screen that when wet, it looks like a piece of sheet
metal because it’s so fine. We replaced it in this case since it took a week to
get it. Unless it’s seriously contaminated, a thorough cleaning could allow it
to be reused.
Photo 8: Factory filler is designed for all VAG cars.
With the pan and new gasket in place, the level tube was
reinstalled but not the level-check plug. The filling bottle was prepared with
the new fluid, and hung from the hood latch loop (see Photo 7). Although the
factory fill bottle isn’t absolutely necessary, it has paid for itself in
allowing this job to be completed in a much more controllable manner. In this
case, the filler plug is on the differential housing, high on the back of the
transaxle (see Photo 8).
1. To start the procedure, the transmission temperature must
be under 30° C, with the dispenser valve and tube inserted in the fill hole. On
other VAG cars, the hooked end of the dispenser makes more sense as the fill
hole is in the pan and an internal tube prevents easy filling without the
special filler. The valve is turned to the open position and fluid fills the
transmission pan until it starts to drip from the check hole. With the
dispensing valve closed, the car is lowered and a scanner is attached to the
DLC connector under the dash.
2. Following the instructions for your scanner, access the
transmission and look for transmission data. You will need to monitor
transmission temperature during the fill process. A less precise way to do this
would be to use a temp probe or non-contact thermometer, but getting actual
fluid temps this way could be difficult.
3. Route the fill hose and scanner cable to avoid contact
with any moving or hot components. Run the lead from the scanner to a place
where it can be read with the car on a lift, start the car in park and let it
idle. Raise the car in the air and allow the transmission fluid to warm while
monitoring with the scanner.
4. As the fluid temp rises above 30° C, open the dispensing
valve and allow the transmission and torque converter to fill. It will take a
few minutes, so keep track of the fluid temp and watch for the fluid to start
spilling out of the checking plug hole. It will be obvious that by not filling
in this manner, it would be impossible to get enough fluid into the
transmission for proper operation, or result in grossly overfilling and causing
similar problems or leaks due to excess fluid.
5. Once the fluid has reached 40° C (higher in warmer
climates; see the specific repair manual), add or remove fluid until there is
just a small amount of fluid coming from the level check hole. Remove the
filler unit and install the plugs at the check hole and filler hole.
6. Check for leaks and do a road-test. A final check for
codes is a good idea. This service often makes a significant difference in
trans operation, and will most likely save your customer a lot of money and
gain you a new customer for life.
FINDING THE SOURCE OF ENGINE LEAKS
Leak detection and repair can be a constant struggle for any
shop. Tracing the actual source of a minor leak is always a challenge. With
engine compartments getting smaller and crammed with even more equipment, even
a small leak can require removing a number of components to actually determine
the leak’s source.
For example, a leak appeared to be coming from under a
twin-turbo A6, at the rear face of the engine, and it could have possibly been
a head gasket or coolant transfer tube. After removing the intake manifold, the
source was obvious; an auxiliary coolant pump is mounted in the valley between
the heads.
Other common leak points with these engines are oil leaks at
the valve (cam) covers, camshaft tensioner and the valley pan on early models.
All of these leak points require some investigation to determine the actual
source before repair.
BELTS AND CAM SEALS
Photo 9: There are several choices for replacement seals, so choose carefully to get the best repair.
I’ve covered the timing belt replacement procedures on cars
with the 4-cylinder and V6 engines in previous articles. Space restrictions are
a problem with almost all models. The removal of the front bumper cover and
movement of the core support (lock carrier in VAG speak) to the service
position is mandatory on non-transverse models.
On the TT, the procedure is the same as on the New Beetle
and Golf variants. This is one repair where it’s very important to know exactly
which engine series you’re working on. There have been a number of design
changes and different repair procedures, as well as updated parts to consider
when replacing the belts on especially the 4-cylinder DOHC turbo cars.
The basic differences are whether the water pump is
externally mounted and driven by a serpentine belt, or internally driven by the
timing belt. Failures of the water pump impeller are common on all engines. An
inspection of the water pump while the timing belt is off is a good idea, if
you don’t have an automatic replacement policy. I recommend the use of an
aftermarket water pump with the metal impeller, for a more durable repair.
On the models with the external water pump, it’s easier to
remove the thermostat cover than the water pump to inspect for a cracked or
otherwise damaged impeller.
One update that is a little controversial for all of the
engines is the cam seals and the update to a springless (PTFE) design. Talking
to several shops about what they’re using has given me several opinions and
cautions. A close look at the various designs (see Photo 9) available for
replacing the seals reveals several things to take into account when selecting
replacement parts. The brand (OEM or aftermarket) makes a lot of difference in
quality, material and design. The OEM parts are also conditioned on where the
engine or car was built.
My personal recommendation is this: If the repair is a
one-day timing belt, water pump and seal job, do not use the updated PTFE
seals. To properly install the PTFE seals, everything needs to be clean, dry
and the shafts cannot be rotated for at least four hours after installation.
They should only be installed on a shaft that shows no obvious wear pattern
(like a radial groove).
On a cylinder head overhaul (e.g. bent valves due to timing
belt failure), there is plenty of time to take the extra steps to use the new
design seals, and take the precaution to allow them to seat before starting the
engine. I’ve had no failures of the updated seals when installed correctly and
carefully.
If you’re using the original spring-type seals, using the
installation sleeve on the shaft can make the difference between a proper
reseal and a comeback. Look closely again at Photo 9 of the three seals and you
can see why some of the OE seals fail quickly (when the spring rolls off during
installation).
UNDERCAR SERVICE
Photo 10: Cracking of the brake flex lines is very common on these cars.
There are two undercar areas to look for service: the front
brake flex lines and the front suspension.
The front brake flex lines on these cars tend to crack at
the connection point to the caliper (see Photo 10). Although the
manufacturer has recalled some of these cars for this fault, not all are covered.
Even if you’re not doing brake work, this is one inspection that should be done
on every VAG car that comes into your shop. Replacement hoses are readily
available, but again, specific hoses are needed depending on how the car is
equipped.
Like the cautions earlier concerning identification of the
engine and transmission, there are several very different brake systems used
throughout this model run, so be ready to pick parts based on rotor diameter
and caliper design.
The front suspensions on the A4 and A6 cars are a
multiple-link system with up to four ball joints. The ball joints are not
replaceable, but instead need to be replaced with their respective suspension
arm. Most problems are with the upper ball joints where they attach to the
bearing carrier. By grasping the wheel front and rear, and turning (steering
action) slightly, the joints will very obviously show wear and vertical
movement. Do not mistake this movement for the tie rod ends, which are also
prone to failure on the earlier models in this series (many were recalled).
There are upgraded parts for most models, which may need to be replaced in sets
for a proper repair, so check all applicable TSBs.
Adding VAG cars to the list of models serviced by any shop
will ensure maintenance work for a long time to come. Since many tools, parts
and software interchange between VW, Audi and even some Porsche models, the
purchase of specialized equipment is well worth the investment.