Oil contamination in this context refers to the presence of small particles in the oil itself.  This could include dust from a recent oil change or metal particles from previous engine trouble.  Most particle contaminants will be caught when passed through the oil filter.  However, if these small particles reach the turbo it can cause severe damage.

The turbocharger design on Volkswagen TDI engines does not use bearings.  Rather, the turbocharger shaft floats on a small film of oil that coats the inner race of the solid brass bearing.  A particle in that film will function as a piece of sandpaper and grind away the surface of the shaft and bearings.

Shaft! Can You Dig It?

The image above shows the grooved wear indicative of a particle caught between the bearing and the shaft.  The gold color of the left side worn areas comes from material transfer of the brass bearing.  The right side did not experience material transfer.

The outside material of the turbo shaft is often hardened, and therefore more durable than the inner metal.  Once a contaminant wears though the hardened surface failure occurs very quickly.

Groovy!

The same grooved pattern is seen on the inside of the bearing as well.  This wear widens the tolerance between the shaft and the bearing, allowing the turbine wheel to move latterly, this is more commonly referred to as “shaft play”.

Final turbocharger failure occurs when the turbine wheel itself contacts, or collides at high speed, with the housing.  The turbocharger housing will alter its shape when heated, and the grooved wear finally creates enough looseness that the wheel itself is unable to spin without contacting the heated turbocharger housing.

Maintaining proper turbocharger health in your Volkswagen TDI revolves around keeping to the maintenance schedule of 10,000 mile oil and filter changes.  If you live in or drive through dusty environments it may be worth considering switching to a shorter oil change interval.

Cabin filters are often neglected. And neglect can affect quality of the air inside your car and a very dirty filter can restrict airflow, causing you to be warmer or cooler than you’d like.

Here’s how to change the cabin filter.

Where is it?

VW moved the cabin filter from under the rain tray in the engine compartment to behind the glove box in the passenger cabin with the introduction of the 5th generation of the A platform cars. You can get to it by looking up at the glove box base in the passenger footwell.

Replacing the filter

Replacement is easy. All you need is a standard screwdriver.

There’s a piece of carpet in the top of the passenger footwell, between the glove box cover and the firewall. It’s held in place with two screws. Remove the screws and pull the carpet out.

Once you’ve removed the carpet, you’ll see a narrow piece of plastic that holds the filter in place. Slide it towards the passenger side door and it’ll come out.

Pull the old cabin filter out and slide in a new one.

Replace the plastic cover, and screw the carpet back into place.

You’re done!

Special thanks to TDIClub member btcost for both the vehicle and doing the actual work!

TDIs are sensitive to fuel quality. And the fuel filters on A5s, in particular, seem to require following a strict change schedule. Hard starting, loss of power, poor fuel economy—these are all symptoms of a clogging fuel filter.

As A5 TDI owners know, VW has flip-flopped on fuel filters for A5 platform TDIs. In this how-to we’ll help you identify what fuel filter your A5 uses, and step you through the filter change.

Which filter does my A5 use?

A5 chassis cars (2005.5-present Jettas) used three fuel filters. Two of them are, for all intents and purposes, identical, and one is different. Here’s the breakdown:

• 1K0 127 434: Used by early A5 cars, engine code BRM, with the last six digits of the VIN starting in numbers up to 83.
• 1K0 127 434A: Visually the same as the filter above, same applications.
• 1K0 127 434B: Used on late 2006 and 2006.5 A5 cars, engine code BRM, with the last six digits of the VIN starting in numbers higher than 83

Here’s where it gets a bit confusing. VW completed an additional production run in late 2006, probably to provide cars for sale during the 2007 model year, where no TDIs were sold in the US. At some point they re-started the counting on the last six digits of the VIN, so you can have a late 2006 car with a very low VIN (last six starting with 00 or higher). These cars also use the 1K0 127 434B late filter.

When VW introduced the CBEA engine in the 2009 Jetta, they went back to using the early fuel filter. The 1K0 127 434 and 434A filters will fit these cars, same as it does the 2005.5 and early 2006 cars.  HOWEVER, 2010 Golf TDI uses the late style filter.  There is a good thread on TDIClub, What Fuel Filter Do You Have?

If you’re in doubt about which filter your car takes, best bet is to remove the top of the filter canister according to the instructions below and take a look. The pictures in this how-to are of a 2009 CBEA Jetta, so it has the early filter. The tip-off is the 5 circle gasket in the cover, and the hole in the top of the filter.

Service interval

The recommended filter change interval on BRM and CBEA TDIs is 20,000 miles. Many BRM owners experienced symptoms of filter clogging much sooner than the 20K change interval, and have adopted the practice of changing the filter every 10K, when they change the oil. Fuel quality probably has a lot to do with filter life, so you may have a different experience based on where you purchase your fuel. It’s your choice.

Changing the filter

The filter sits in a large canister behind the passenger side headlight in the engine compartment. Start by removing the bolts on the filter canister cover (T27 bolts).

Carefully pry the top off the canister and move it aside, and set it on some towels to prevent fuel spilling.

Here you can see the 5 hole gasket that indicates an early A5 or CBEA fuel filter.

Pull the filter out of the canister. It will probably appear black. This is caused by some chemical change in ULSD when heated.

Once the top is off the filter canister, we recommend removing and draining the canister itself, as the action of removing the filter may dislodge debris that will remain in the canister unless you drain it. Contrary to some printed information, there is no drain on the bottom of the canister.

There are two 13mm bolts holding the canister in the car. Remove those and you can pull the canister out of the car.

Drain the fuel out of the canister for disposal.

With the canister out of the car, remove the 5 hole gasket and replace it with a new one, provided with the replacement filter

Place the new filter in the canister

There’s a large sealing ring on the canister top. Remove and replace the seal with the one provided with the filter.

Once you’ve put the new filter in the canister, bolted the canister back in place, and replaced the seals, you can replace the canister top. It will only go on one way: there’s a pin in the top and a hole in the canister to align the top.

Fit the top back on the canister and tighten the bolts. Note the bolts are quite soft and should not be overtightened. The seal will work: Don’t make them too tight.

One benefit of the A5 over the earlier cars is the in-tank lift pump will fill the canister. Cycle the key twice to make sure the canister fills, and start the car. It’s probably a good idea to keep the revs up around 2000 for 10 seconds or so to make sure the car doesn’t stall as it clears any accumulated air out of the fuel lines.

You’re done!

Remember to be sensitive to any loss in power or hard starting that may indicate a clogged filter. If you have persistent filter issues at a shorter than 10K change interval you may want to change fuel sources.

Special thanks to TDIClub member btcost for the car and the actual work!

VW TDIs are turbocharged engines with precise air metering. This means that the intake air has to be clean to protect the turbo and Mass Airflow Sensor. It also helps to keep moisture out of the air system where possible. And the airbox on a TDI should seal well to protect both against dirt and innacurate Mass Airflow readings.

Even though most folks agree that the manufacturer’s recommended 10,000 mile oil change interval is the way to go, there’s lots of debate regarding how often to replace the air and fuel filters in TDIs, especially CBEAs. Some people change air filters as often as every 10,000 miles, but most feel every 20,000 miles is a good interval. Whatever change interval you choose, the filter change is quick and easy. Here’s how to do it.

What will you need?

Air filter, part number 1K0 129 620 or 620A. The difference between these two filters is the number ending in the letter A includes a pre-filter. CBEA engines have a two part airbox that can draw air from inside the engine compartment if the snorkel to the outside is blocked. The prefilter helps keep moisture out of the engine when the airbox is accessing air from the engine compartment.

Many people decide to save a few dollars and forgo the prefilter. Whether or not you use one is up to you. However, we believe that all CBEA TDIs in North America were delivered with pre-filters. It’s your choice.

All you’ll need is a Phillips head screwdriver for this swap. Easy.

Changing the filter

There are a total of six screws on the top of the air filter box, four on the filter and two on the MAF connector. Remove the four airbox screws

Then remove the two screws on the MAF connector.

You can see all six screws in this top down view

Once the screws are out, lift the cover and remove the filter. Here you can see the old (20K) and new filters side-by-side.

If you look at the dirty filter you can see the line made by the partition in the airbox.

Put the new filter in place. It should fit snugly. Press the cover into place and replace the screws. You’re done!

A final note

Folks sometimes like to open their airbox to take a look at their filter to see if it’s time for replacement. This isn’t a good idea. Manufacturers maintain that the gasket on the filter is designed to seal—once. Technically, if you open the box you should replace the filter as it won’t seal as well the second time.

Anyone who’s done any research on VW TDIs know VW has some very specific oil requirements for these engines. And the requirements change with each new generation TDI. The ‘09 and later TDIs with common rail engines (Engine Code CBEA) require oil that meets VW’s 507.00 specification. Castrol has joint ventured with VW to create an oil for this purpose, and Total, Lubro-Moly, and some other refiners also have an oil that will work in this engine.

Many owners worry about the dealer or repair shop putting the correct oil in their TDI. The best way to be sure is to do it yourself! This how-to shows how easy it is to do on your own.

In this how-to we’ve changed the oil using the traditional method of removing the drain plug and draining the oil from the pan. Many owners prefer to use an extractor to pull the oil out of the pan through the dipstick tube. The CBEA can make this a little more challenging than earlier TDIs because of baffles in the pan. So we’re showing the old-fashioned way.

What will you need?

Pretty simple:

• An oil filter, VW Part Number 071115562C. These filters are made by Mann (VW OE), Mahle, and other makers
• Five liters of 507.00 oil
• A new drain plug or crush washer for your existing drain plug

Some VW drain plugs have captive washers. Most folks recommend replacing them when changing the oil. Many owners have re-used them with no ill effects. It’s up to you.

You’ll also need the following tools:

• Torx wrenches (T25 & T27) to remove the lower engine cover
• A 19mm wrench (box, socket, or open ended—3/4″ will also work)
• An oil drain plan
• Water pump pliers or an oil filter wrench to remove the top of the filter canister
• A small screwdriver or pick to remove the O-rings from the filter canister cover
• Some paper towels to protect some areas of the engine compartment and clean up
• A way to get the nose of the car in the air: ramps, jack stands, or, best yet, a lift. Please do not use a jack to support the car, it’s not safe.
• Rubber gloves are really helpful, too, and plan on getting oil on your clothes. It seems impossible to avoid, at least for some of us.

Preparation

The oil should be warm and have circulated through the engine just before changing. Best way is to drive the car a few miles (5 would be plenty) to warm up the oil and make sure the impurities are in suspension. Don’t drive too much or the oil will be unpleasantly hot.

Draining the oil

Get the front of the car high enough in the air so you can reach under it and remove the lower engine cover. Once the cover is off and out of the way, put a drain pan under the oil pan. Use the 19mm wrench to remove the drain plug. Remember the head of the bolt is pointing away from the front of the car when you decide which way to turn it.

Remember the oil will flow rearward, make sure it isn’t going to miss the pan.

Once the drain plug is out, let the oil drain and turn your attention to the filter.

Removing the filter

Many VWs now have paper filter cartridges that live in a canister on the left side (towards the radiator) of the engine. This system makes changing the filter significantly easier and neater than removing a spin-on filter.

The canister has a black top, and what looks like a very large nut on top of it. It’s probably bigger than the sockets you have (about 35mm). If you have one that will fit, use it to loosen the top. If not, you can use a pair of water pump pliers to loosen the top.

Remove the filter canister top. There’s a wrapped line in front of the canister that’s covered in heat insulation. You may want to protect that from drips by covering it with a paper towel.

Once the top is off, pull the filter out of the canister. You may want to have a plastic bag available to put the filter in as soon as it comes out to reduce dripping

Sometimes the spindle on the filter will break off in the canister, as it did in the center of the picture below. If it does, you’ll have to remove it with a pair of pliers. Some people also like to use an extractor to remove the last bits of oil from the filter canister.

Once the canister is clear of the old filter, including the spindle, you can put the new filter in place. It’s pretty easy to get right side up as the spindle points down.

Open the o-ring that came with the filter and replace the one on the canister top. Put the top back on. Tightening torque is very little, about 8 ft/lbs. You really don’t need to make it more than barely hand tight. The gasket will do its job.

Putting it back together

Replace the drain plug. Torque spec is not a lot, about 12 ft/lbs. Remember the pan is aluminum and you don’t want to damage it.

Be sure you’re using the right oil

Put 4 liters in the car, check the dipstick. A5s have what we think is one of the world’s most confusing dipsticks, so you may want to consult your owner’s manual to be sure of the correct level

Once the car’s buttoned up and at least 4 liter of oil is in it, start it up. Check for leaks. Shut it off and check the oil. If the nose of the car is in the air, don’t fine tune the oil level until the car is level.

If you’re satisfied that you’re leak-free, replace the lower engine cover and put the car on a level surface. Let it sit for a few minutes and then check the oil. Add oil as needed. You should have about ½ liter left when you’re done.

Congratulations!

Many of us changed our own oil when we were in our teens, but have gotten away from it as work, family, and other demands (or lack of a place to do it) got in the way. It’s one of the simplest things you can do for your TDI. And it’s rewarding to know that you’ve done it right with the right spec oil.

Changing Injection Quantity (IQ) is easy. Here’s how to do it.

Cable/Software/Port Setup

This how-to assumes that you’ve got your VAG-COM, downloaded the software, and made sure your car can connect to your computer. If you haven’t done this yet, www.ross-tech.com has detailed instructions.

Checking and Changing IQ

You car has to be running to get an accurate injection quantity reading. And it has to be up to operating temperature. So it’s best to drive the car for 20 minutes or so, some of it at highway speeds, to make sure you’ll get a good reading. You should not run your A/C during this test, as it will affect readings.

The screen prints in this article are from a 1997 VW Jetta TDI. If you have a different TDI some of the data displayed may be slightly different, so keep that in mind as you proceed.

You’ll first see this screen:

This is where VAG-COM launches. Click on the button named Select under the the words “Select Control Module.” Next you’ll see this screen:

All the engine control modules are listed, even if your car doesn’t have some of them, such as ABS. Click on 01-Engine to proceed and you’ll see something like the following screen:

The engine data will take a moment to populate. Newer cars populate faster than older ones (slower ECUs). Once the screen is populated, you can click on Login-11 to first login:

Type the numbers 12233 into the box to the right of the words Enter Code and click on Do It! This will take you back to the Engine screen:

This time click on the button Adaptation – 10. Next the screen below will appear:

However, you’ll see channel 00. Click the Up button to Channel 01 and you’ll see Adaptation numbers.

At the top of the screen you’ll see RPM and Injection Quantity. The IQ will most likely be a number between 1.0 and 3.0.

Next, look at the numbers on the left side of the screen. Below the Channel window you’ll see two boxes, one titled Stored Value and the other titled New Value. The default stored value is 32768. If your IQ has been previously adjusted you may see a different number. There’s a limit on the number range for IQ, it varies by ECU, but is approximately between 32645 and 32786.

The IQ measurement numbers are slightly counter-intuitive. A higher Injection Quantity (such as 3.0), will flow less fuel than a lower quantity (such as 2.0). And a lower new value (such as 32725 instead of the default 32768) will flow less fuel than a higher new value.

Why change Injection Quantity?

If your car:

• Smokes more than you want
• Shudders at slow down or idle

You may want to reduce fueling (increase the IQ number)

If your car is low on power, you may want to increase the IQ number.

Changing IQ

Here’s how to do it. On the adaptation screen, shown below:

Click into the New Value box and type in a new number. If the stored value is 32768 and you want to reduce fueling, try a lower number such as 32750 or 32725. Click on Test at the bottom of the screen. The IQ number will change (and your engine tone will change, too). Look at the new Injection Quantity at the top of the screen and see if it’s what you want. You can further adjust the IQ by typing in a new number and clicking on Test, or by using the up and down buttons to the right of the New Value box.

Once you’re satisfied with the IQ and want to test drive the car to gauge results, click on Save at the bottom of the screen:

You’ll be asked, Are You SURE?

Click on Yes to save the new setting. If you want, you can drive the car with the computer hooked up to determine if you’ve achieved the result you were after (more power, less shudder), and further adjust the IQ if needed.

Once you’re satisfied, click on Done, Go Back at the bottom of the screen, Back on the engine screen, and Exit on the main screen to exit VAG-COM.

Done!

One of the most basic VAG-COM uses is checking timing after a timing belt change. We’ll walk through that process here. In addition, adjusting your timing to be slightly (or more) advanced can improve cold starting, accelerator response, and fuel economy. So there are a lot of good reasons to have your timing set properly.

Here’s how to check.

Cable/Software/Port Setup

This how-to assumes that you’ve got your VAG-COM, downloaded the software, and made sure your car can connect to your computer. If you haven’t done this yet, www.ross-tech.com has detailed instructions.

Checking Timing

You car has to be running to check the timing. And it has to be up to operating temperature. VAG-COM also measures fuel temperature, and will provide slightly different readings if the fuel is cold. So it’s best to drive the car for 20 minutes or so, some of it at highway speeds, to make sure you’ll get a good reading.

The screen prints in this article are from a 1997 VW Jetta TDI. If you have a different TDI some of the data displayed may be slightly different, so keep that in mind as you proceed.

You’ll first see this screen:

This is where VAG-COM launches. Click on the button named Select under the the words “Select Control Module.” Next you’ll see this screen:

All the engine control modules are listed, even if your car doesn’t have some of them, such as ABS. Click on 01-Engine to proceed and you’ll see something like the following screen:

The engine data will take a moment to populate. Newer cars populate faster than older ones (slower ECUs). Once the screen is populated, you can click on Basic Settings-04 to see the timing data, shown below:

When this screen appears you won’t see the blocks with timing data as shown above. Hit the Enter key on your laptop for this data to display, or click the Up button under the Group label to Group one, and then click back Down to Group 000 to display the timing.

The data you’re after is in Block 2. In the sample screen it shows a timing setting of 64. Although the measurements vary by vehicle, this timing is advanced but within spec for most TDIs. If you want to see a graph click on the TDI-Timing button on the lower right of the screen and you’ll see the following:

This screen shows several pieces of data.

• The Red, Blue, and Green lines show the limits of timing within spec, from most retarded (red), to normal (blue) to advanced (green). The yellow line shows how the timing is set on your car. In this example it’s advanced, but within specifications.
• You’ll see fuel temp in the lower left of the screen. It shows 95F here. If the fuel is too cold you’ll see a warning message at the bottom of the graph.
• Also at the bottom of the graph you’ll see Result. In this case it says Timing within spec slightly advanced.
• However, on the right side of the graph you’ll see a drop down box where you can select the engine that most closely matches your car. And in this case you can see a 1.7l R4 SDI selected, not the 1Z/AHU that an A3 Jetta has. So the graph is calibrated for an engine different than the one in the sample car. You should choose a graph that most closely matches your engine (which we failed to do here) to get the most accurate data on your car’s timing

What do I do with the data?

As previously mentioned, timing settings can affect starting, power, and fuel economy. And timing that is way off can potentially damage your engine.

If you don’t see any data on the graph, or if your timing number is over 150, your timing may not have been set properly when your car was serviced. Your timing belt may be off at tooth, or even two.

The ECU will do its best to correct timing issues when the engine is running over 1600 RPM. Since the timing measurement is taken at idle, you won’t see any ECU correction in the screens above. And the ECU cannot compensate for retarded timing in during a cold start.

Correcting Timing

In rotary pump cars, timing should be set mechanically, not in VAG-COM. Tuners will fine-tune timing in VAG-COM, but it’s generally accepted that the best way to set timing is by changing pump position (1Z and AHU) and the pump cam (ALH). Timing can be fine-tuned in VAG-COM in Pumpe Deuse TDIs, which will be the subject of a future article.

505.00, 505.01, 507.00 – What do these mean?  10,000 mile oil change interval?  Really?  5W-40, 5W-30, 0W-30, which is better?

Driving a VW TDI means questioning and sometimes tossing out some long-held beliefs about oil and oil change intervals (OCI).  Pulling into your local quick-lube store and letting them put whatever’s in the drum below the floor into your car can be disastrous to your TDI.  We’re going to try to make it simple and help you choose the oil your TDI requires.

Why is Correct Oil so Important?

If you drive a TDI you already know it’s a remarkable engine.  Few, if any other engines offer a comparable combination of power, economy, and longevity.  However, several aspects of the TDI’s design make it hard on oil.

First, the TDI’s high compression puts its piston rings very close to the point of combustion.  Engineers soon learned that conventional oils could leave deposits, or coke, on the piston rings, which would jeopardize their function, increasing oil consumption.

Second, Oil is the life blood of a turbocharger.  If oil cokes or gathers residue then it can clog the turbo oil feed line, starving the turbo of oil and ending its life.  Not a good thing.

Third, newer TDIs (‘04 and later) have injection systems that are generate very high fuel injection pressures but are also hard on camshafts.  These cars require oil that can keep cam lobes lubricated in that high pressure environment.

Fourth, TDIs emissions systems have become much more sophisticated in recent years, requiring oils to be refined without components that can harm those systems.

Finally, all manufacturers are after maximum fuel economy and the longest possible oil change intervals in all their cars, and keeping oil in cars longer while providing the best possible fuel economy figures put additional demands on oils.

Oil Standards and Specifications

VW has established and tests oils to standards it has set for its engines.  There are several other industry standards for engine oils, but for simplicity we’ve stuck with VW’s standards here along with oil viscosity measures that are commonly used in the US.

Will oils that do not meet or include VW standards work in your TDI?  Probably.  Oils that meet other standards such as ACEA or API may be fine for your VW.  In fact, some owners purposely use oil that does not meet VW’s specifications because they believe it’s better for their TDIs than the ones VW certifies.   Just keep in mind that VW may ask for proof that your car has used only oil meeting their standards in the event of a warranty claim.

Synthetic versus Non-Synthetic

This distinction is not as simple as you may think.  Although all the oils that meet the standards in the chart above are considered synthetics, many of them may start with mineral oil base stocks, or esters.  You’ll see terms like “synthetic technology,” or “pure synthetic,” on labels.  But once again, if it meets the standard, it’s OK.  And in the world of TDIs, if it meets the standard it is going to be synthetic oil.

Diesel Versus Gasoline

There’s a simple point here: Diesel engine oils have different requirements because, in part, of the need to keep soot in suspension in the oil between changes.  You’ll notice that the oil in your TDI turns black very quickly after a change.  That doesn’t mean it’s dirty, it is keeping the soot the engine generates in suspension.  The presence of that soot is an oil design consideration.  There are many oils that meet both gasoline and diesel standards, but beware of oils that are designed only for gasoline engines, even if they are synthetic.

Match the Rating to Your Engine

The table below lists the TDIs sold in North America and years they were sold, the oil they require, and some (not all) of the oil brands that offer oils that meet the standard.

The brands listed here are not exhaustive, there are others.  And there are yet more oil brands that claim to be “designed for engines with 505.00 (or 505.01) oil requirements”, or words to that effect.  Just keep in mind that if the VW standard isn’t printed on the label, the oil probably hasn’t been certified by VW.  It’s your choice whether or not to use that oil.

What about 506.00?

VW has a 506.00 standard for oils that were considered good to use in cars that require 505.01 oils (PDs), and was also specified for the V-10 Touareg.  This was a 0W30 weight oil that helped improve fuel economy.  However, 506.00 oil was very expensive and did not match the lubrication or protective standards set by 505.01, and has been phased out.  The Lubro Moly Top Tech 4200, a higher 507.00 specification oil, is also specifically approved for vehicles requiring 506.00 and 506.01.

What about Weight?

Europe and America use multiple viscosity ratings for oils.  And there are a couple of trends in the oil industry when it comes to viscosity:

• Oil viscosity numbers are getting lower
• Lighter weight oils work better than they used to at high temperatures

Emissions and fuel economy requirements have, in many cases, driven manufacturers to use lighter weight oils.  Since EPA measures include a cold start, light weight oil helps cars perform better in that test.  Also, engine tolerances are much tighter than in past years.  Thinner oil (especially when cold) can help provide lubrication during those first few critical seconds after a cold start.  And today’s synthetics provide much better protection when hot than mineral-based oils did, even if their viscosity rating is lower.  For example, 5W30 weight oil is considered fine for all driving conditions in PD and Common Rail TDIs, even in the desert in summer.

505.00 oils (for rotary pump TDIS) have the widest viscosity ratings of VW oils, and include 0W30 and 0W40.  Although 5W40 oil is most popular in this category, many owners in cold climates like using 0W30 or 0W40 in winter.

And both 5W30 and 5W40 oils are available for oils meeting the 505.01 standard (PDs).  Both are fine for use in all climates, although some owners prefer 5W40 over 5W30.

10,000 miles?  Really?

All TDIs have a 10,000 mile oil change interval (OCI) after break-in.  After generations of 3,000 mile OCIs many owners have difficulty accepting the 10,000 mile interval as safe.  But 10,000 miles has proven to be a more than reasonable interval.  Many owners run their oil longer.  TDIs are proving to last many hundreds of thousands of miles without major wear using a 10,000 OCI with the correct oil, and many feel it’s wasteful to change it more often.

Soot build up is the primary reason for oil breakdown in diesels.  As oil advances further technologically the different specifications have been increasingly tolerant of high soot levels in the oil.  This results in many european vehicles with flexible service intervals to go 30,000 miles or more between oil changes.

Summary

Simple enough.  If your car:

• Has a rotary injection pump, use oil that meets VW’s 505.00 standard
• Is a PD, use oil that meets VW’s 505.01 standard
• Is a Common Rail, use oil that meets VW’s 507.00 standard

Diesel on!

How often should I do this?

VW and the Bentley manual recommend every two years regardless of mileage. My local VW dealer would do it with the 40,000 mile service. When I just did this, it had been 2 years or 46,000 miles since the last time it was done.

How much brake fluid is needed?

1 liter may be sufficient, but I suggest getting more to be on the safe side, especially with a manual. I used 1.1 to 1.2 liters.

Items needed:

• Motive Power Bleeder
• Brake Fluid
• 11mm wrench
• Jack
• Jack Stands
• Lug nut wrench
• Empty bottle or other container for fluid
• Turkey baster
• 10mm socket with extension (airbox removal)
• Clamp removal pliers (airbox removal)

What kind of brake fluid is needed?

Any brake fluid that meets DOT4 spec is sufficient.  There are blue versions and amber versions.  Some people like to switch between the two to make it easier to see when you have new fluid coming out, but this is not necessary.  Some people do not recommend using the blue with a manual transmission car, as it can cause the clutch to squeak.  I personally used an amber fluid, when there was amber already in the system, and had no problem identifying when new fluid comes out, as the old fluid will be darker.

What kind of variances are there?

Automatic transmissions will not have a clutch valve to bleed.  If you have a 6 speed manual there may be differences in bleeding the clutch.  MkIV’s up to 2001.5 use the pattern (bleed rear passenger side first, clutch last) I describe, beyond that use the reverse of the pattern (clutch first, rear passenger side last).

1. Open the hood and remove the airbox (not necessary, but it makes the job easier, especially with a manual).  There are two 10mm sockets holding it down, one is by the strut tower, and the other one is between the airbox and the battery box, this requires an extension.  Then unplug the MAF, and squeeze the spring clamp with pliers and remove the hose from the airbox.  You may want to stuff a rag in the hose to prevent debris from getting in there, but this is not necessary if you are careful.

2. Break the lugnuts on the wheels loose in preparation for their removal, but do not remove them yet.  It is possible to do this without removing the wheels, but it makes it easier.

3. Jack up the rear passenger side, put in a jack stand to keep the car up.  Remove the rear passenger side wheel.

4. Go back under the hood and remove the sensor on the fluid reservoir.  Remove the cap by unscrewing it.  Leave the screen in the reservoir.

5. Take a turkey baster and an empty container and suck out as much fluid as you can and put it in your container.  Refill the reservoir with your choice of brake fluid, up to the max fill line.

6. Attach the end of the Motive Power Bleeder to the reservoir, but don’t put any fluid in the bleeder.

7. Pressurize the bleeder to 10 psi.

8. Go to your rear passenger brake caliper, locate the bleed valve.  Remove the black cover from the valve.  Attach one end of your drip tube to the bleed valve, and put the other end in your container for holding the fluid.

9. Using an 11mm wrench, open the bleed valve slowly until you have a stead flow of fluid out of the tube.

10. Watch the resevoir and the power bleeder, when either gets low, close the bleed valve.  I suggest stopping when the bleeder has gotten to 8.5 or 9 psi to get a feel for how much fluid it is using.  Don’t let the fluid get too low, otherwise you will get air in the system, which is not good.

11. Unscrew the cap to the power bleeder to relieve pressure, then uscrew the end on the resevoir.  Refil the resevoir and repeat the above process until you see new fluid coming out of the bleed valve.

12. Replace the rear passenger side tire, then remove that side from the jack stand and slowly un-jack it.  Repeat the above process for the rear drivers side, then the front passenger side, then the front drivers side, and finally the clutch if you have a manual.

13. The bleeder valve for the clutch is harder to get to, you will need to leave the front drivers side on a jack stand and get under the car to attach the drip tube to the bleeder valve and let it run to your container.  It helps to have the airbox out to see where the bleeder valve is.

14. Bleed this like you did for the other ones.  Replace the front drivers side wheel if you haven’t done so already, and remove the car from the last jack stand.

15. Refil the resevoir up to the max fill level, and replace the cap and sensor.  Replace the airbox.  Take the car for a quick test drive to ensure proper performance.

16. You’re done!

Choosing between a stock or bigger turbo

Deciding whether to replace your turbo with another one just like it or to upgrade can be a complex decision. Or, it might be easy, because there may not be a larger turbo available that will easily fit your TDI. If there are upgrades available for our car, you should consider:

• A bigger turbo may not provide more power unless you make other upgrades (chip tuning, more fuel, better breathing)
• Bigger turbos may require supporting hardware for an easy install that can add to the replacement cost
• With larger turbos many expensive modifications may be required to take full advantage of the turbo’s potential

For example, a VNT-17 on an A4 TDI is a solid, well known upgrade. But it requires a $200 hose or a $100 adapter to fit stock intercooler piping. And bigger injectors (about $300), a chip tune ($300-700+), downpipe ($300-400), and improved intake (costs vary) are required to take full advantage of the power it supplies. And of course you’ll need a clutch. So you can see that choosing a bigger turbo is just the tip of the iceberg.

Many people consider a bigger turbo in hopes of improved reliability. And there are situations, even in stock cars (such as high altitudes) where a bigger turbo may last longer than the OE turbo, so this is a valid consideration.

Limited selection for some TDIs

For some TDIs there are very few options. For others, there are many. Let’s deal with the ones where choice is limited first.

• A5 Jetta, engine code BRM: Your option right now is a stock replacement turbo from VW, or a custom fabrication of manifold and turbo. No plug-and-play turbos that fit this car are in the US aftermarket—yet. With the A5 VW switched the turbo configuration to a top mount (the turbo sits on top of the manifold, not hanging below it as in earlier cars), so turbos from other TDIs won’t fit.
• B5.5 Passat, engine code BHW: This TDI has a separate turbo and manifold. Although there are probably many turbos that can be made to fit, the VNT-17, or Garrett 1749VA, is the only true plug-and-play option that’s readily available. Fortunately this is a great turbo, makes good power, and fails infrequently.



• A3/B4 TDIs, engine codes 1Z and AHU. These early TDIs had wastegate turbos in the US, not the variable vane turbos that are on all later VW TDIs. These two engines are nearly identical, but the 1Z has a Garrett turbo, the AHU has a Borg-Warner. The turbos are interchangeable. Like the B5.5 Passat, these turbos are separate from the manifold. There are other options for these cars including hybrid turbos with larger internals (plug-and-play), and switching to a VNT-15 or larger variable vane turbo (not plug-and-play).

A4 chassis TDIs, lots of options

On 1999.5-2006 A4 platform Golf, Jetta, and New Beetle, there are many turbo options. We’ll limit our discussion here to variable vane turbos with integrated exhaust manifolds. More than a few TDI owners have built their own manifolds, and there are also A4 TDIs out there with wastegate turbos. However, most daily drivers prefer the responsiveness of a variable vane turbo, and don’t want to go to the expense of building a manifold.

Stock Replacements

The ALH engined A4s (rotary pump) came with Garrett’s VNT-15 turbo. A version of this turbo started its life in the A3, but was first sold with an integrated manifold for the ALH engine. It’s very responsive, quite durable (especially if synthetic oil is used throughout its life) and makes great power. The dyno below shows what a VNT-15 can do with a chip and other supporting modifications. And when this dyno was run the turbo had 150K on it.

IBW dyno

The VNT-15 has benefited from running upgrades to vanes, internal metals, and other improvements during its life. It is less prone to carbon clogging (a common cause of failure on gently driven TDIs) than it was in the past. And many owners are out there with over 200K on their original turbos, so they do last.

When the Pumpe Deuse A4 chassis TDIs (engine code BEW) were brought to the US in 2004, VW switched from the Garrett VNT-15 to the Borg-Warner KP-39. This turbo is physically smaller than the VNT-15, but works exceptionally well in both stock and chip-tuned TDIs. 150 HP/240 lb/ft. is possible with this turbo and the right tune. The KP-39 does seem more prone to boost spikes than the VNT-15, especially in modified cars. And they also seem more stressed at high altitudes. Finally, some owners (again, in modified cars) have experienced boost creep at high speeds, eventually sending the car into limp mode. But these problems are neither that common nor catastrophic.

KP-39s just became available in the aftermarket. Because there was such a long delay before they were released, Garrett has made a version of their VNT-17 (1749VB) as a stock replacement for the KP-39

This turbo can be run in a stock BEW, but it also allows more airflow and can handle more boost than the KP-39. 165 HP/270 ft/lbs are possible with this turbo and the right tune and supporting hardware.

Want more?

For several years the VNT-17 was the upgrade turbo of choice for may ALH owners seeking more power. 180+ HP and 350+ ft/lbs are not uncommon.

Installing this turbo is fairly simple. The only major difference between it and a VNT-15 is the compressor (cold side) exit. The VNT-17 has a clip fitting that requires a VW hose or an adapter.

Unfortunately the hose runs about $200, but it allows the VNT-17 to plug right into most A4s. 1999.5 A4s will also need a new lower intercooler pipe, or charge tube, to accommodate the clip fitting at the intercooler end of the hose.

As mentioned above, the VNT-17 is also available as a stock replacement on the BEW, and is plug-and-play on that car. The turbo for the BEW includes a “smart” actuator that provides boost feedback information to the ECU.

Still want more?

If you’ve made other mods to your TDI including air handling (intake and exhaust) intercooling, fueling (bigger nozzles or higher pressure injection pump), and tuning and want more than the turbos listed above can provide, there are more options.

And although the VNT-17 is a popular upgrade on ALH engined TDIs, some drivers have found it less responsive (more lag) than the stock turbo. One way to reduce the lag and increase airflow is to use a larger compressor from a bigger turbo. This is how the 1752, or VNT-17/22, came into existence.

It is a VNT-17 with a compressor housing from a VNT-20. Because the larger compressor is spooling up a smaller exhaust wheel, it is more responsive than the VNT-17. Because it is made of components from two different turbos, it’s called a hybrid. And although its ability to make more maximum power than a VNT-17 is questionable, it does provide maximum torque sooner (lower revs) than the VNT-17 does in most setups. Here’s a dyno of the 17/22 in an ALH with many other mods.

Suppliers have also achieved this result by modifying stock VNT-15 housings to accommodate 17/22 or 18/52 internals. These turbos are available for both ALH and BEW engines, the only difference usually being the actuator. The BEW will usually require intercooler piping modifications for the hybrid intercooler pipe connections to fit properly, depending on the housing used for the compressor.

What to choose?

In summary, bigger turbos can mean more power. But sometimes they can jeopardize driveability with increased lag. Or they cause your car to smoke as they spool up, or cause you to need a new clutch to handle the increased power.

Best way to choose a turbo is to first identify your goal for increased power. Keep in mind that many tuners can improve HP and torque by 30% with a chip alone. Maybe that’s enough and you can stick with a stock replacement. But if you want more, happy shopping.

Related Products

Garrett VNT-15 Turbo (A4-ALH)
Garrett VNT-17/22 Hybrid Turbo (A4-BEW)
Garrett VNT-17/22 Hybrid Turbo (A4-ALH)