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.
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.
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.
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.
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.
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.
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.
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
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).
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.