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VW / Audi Intercooler Cleaning
 
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Pelican Technical Article:

VW / Audi Intercooler Cleaning

Peter Bodensteiner

Time:

1.5 hours

Tab:

$10

Talent:

***

Tools:

Screwdrivers/nut drivers, dish soap, brush, bucket, hose

Applicable Models:

Audi A4 (1997, 1999-01)
Audi A4 Sedan (1998)
Audi A4 Quattro (1997, 1999-01)
Audi A4 Quattro Sedan (1998)
Audi TT (2000-04)
Audi TT Quattro (2000-04)
VW Beetle (1999-02)
VW Golf (2000-02)
VW Jetta (2000, 2002)
VW Jetta Sedan (2001)
VW Passat (1998-00)

Parts Required:

New hose clamps if desired

Hot Tip:

Make sure to allow all of the parts to dry before reassembly

Performance Gain:

Improves efficiency of intercooler

Complementary Modification:

Change diverter valve, install crankcase breather catch can, pressure-test boost path.

A unique part of owning a turbocharged car (or, at least, one with an intercooler) is that the intake tract consists of more than an air filter and a tube leading to the throttle body. Rather, you have the turbocharger itself, some hoses and piping leading to the intercooler, the intercooler itself, and then some hoses or piping leading out of the intercooler and to the throttle body.

With more hoses, clamps, and connections to worry about, there is more chance of an air leak occurring. These leaks can be especially troublesome given that the intake tract is pressurized when the turbo is producing boost.

Another issue is created by the crankcase ventilation system that is part of the modern emissions-controlled vehicle. As the engine oil is churned around in the crankcase and produces oily vapors. This, along with any combustion gases that might make it past the piston rings, are routed back into the intake tract, where they can be fed into the engine and burned, rather than vented to the atmosphere as pollution.

The problem is that some of this oily residue ends up settling along the surfaces inside the intake tract. As oil coats the interior of the intercooler, it reduces the intercooler's ability to transfer heat away from the compressed air on its way to the engine. It takes some time for enough oily residue to build up and become an issue, but over time quite a bit of oil can accumulate.

Another problem is oil in the intake tract is a symptom of a faulty turbocharger, one that is leaking oil out of its lubricated center section. However, if you find oil in the intake tract, how do you know if it is from a bad turbo or simply the result of the crankcase ventilation system doing its job? When I pulled the intake tract hoses off of my 100,000+ mile A4, several ounces of oil drained out--do I have a bad turbocharger, or is that amount of oil normal for a car with this mileage?

The short term solution is to disassemble the intake tract and clean it out. This project will familiarize you with the post-turbo intake path, which also will help you if you're chasing down a boost leak. Also, you'll learn where all the hoses and clamps are located should you want or need to replace any of them.

You may be able to do this project without removing the bumper or moving the radiator support panel into the service position, but they are moved for maximum access in the following photos. You will have to remove the undertray from beneath the engine, and it may be helpful to have the front of the car elevated.

Let's start at the end and work our way back.
Figure 1

Let's start at the end and work our way back. First, unscrew the hose clamp on the end of the hose next to the throttle body, on the driver's side of the engine compartment. A flat-blade screwdriver or nut driver will do the trick.

With the clamp loose, twist and pull the end of the hose until it comes off of the throttle body.
Figure 2

With the clamp loose, twist and pull the end of the hose until it comes off of the throttle body.

Looking into the throttle body, you can see the accumulation of oily residue on the throttle butterfly.
Figure 3

Looking into the throttle body, you can see the accumulation of oily residue on the throttle butterfly. Use a rag to clean this off.

With the bumper removed, this is the view looking straight at the intercooler just in front of the driver's side wheel.
Figure 4

With the bumper removed, this is the view looking straight at the intercooler just in front of the driver's side wheel. The large black plastic piece surrounding the intercooler is a duct that directs airflow to the face of the intercooler to maximize its cooling effect on the intake charge. The intercooler is just like a radiator except instead of coolant flowing through it, air flows through the interior passages.

The top of the intercooler duct is secured to the intercooler at the top with this clip.
Figure 5

The top of the intercooler duct is secured to the intercooler at the top with this clip. Use a screwdriver to lift the flap in the clip and release the top of the duct.

On the bottom, the duct simply sits on these two plastic posts attached to the bottom of the intercooler.
Figure 6

On the bottom, the duct simply sits on these two plastic posts attached to the bottom of the intercooler. Lift the duct up and away.

Here is the intercooler with the duct out of the way.
Figure 7

Here is the intercooler with the duct out of the way. Note the horn and washer fluid reservoir in close proximity.

Loosen the hose clamp between the bottom of the intercooler and the hose that leads back to the hard pipe that is integrated in the radiator support panel.
Figure 8

Loosen the hose clamp between the bottom of the intercooler and the hose that leads back to the hard pipe that is integrated in the radiator support panel.

Here the hose has been removed.
Figure 9

Here the hose has been removed. This is where I found the highest concentration of oil within the intake tract. You can see a little oil dripping out of the hose, but this is just what remained several weeks after the initial quantity of oil was discovered and drained.

ThisPicture shows the entire hose leading from the hard-pipe crossover contained within the radiator support panel to the bottom of the intercooler.
Figure 10

This picture shows the entire hose leading from the hard-pipe crossover contained within the radiator support panel to the bottom of the intercooler.

Let's finish the job of removing the intercooler.
Figure 11

Let's finish the job of removing the intercooler. Loosen the hose clamp connecting the hose to the outlet at the top of the intercooler.

Use a small screwdriver to release the clip holding this wiring connector in place.
Figure 12

Use a small screwdriver to release the clip holding this wiring connector in place. The wiring leads to the charge air pressure sensor.

Here the wiring is disconnected.
Figure 13

Here the wiring is disconnected.

Loosen the hose clamp and remove the top hose from the intercooler.
Figure 14

Loosen the hose clamp and remove the top hose from the intercooler. Note the markings that indicate the proper orientation of the hose to the intercooler outlet; these will be useful during your reinstallation process.

The two prongs extending from the back of the intercooler help mount the intercooler into the metal bracket just behind it.
Figure 15

The two prongs extending from the back of the intercooler help mount the intercooler into the metal bracket just behind it. The round pads on the prongs simply rest in the two holes of the bracket.

The intercooler is now free and can be removed.
Figure 16

The intercooler is now free and can be removed. Note the amount of built-up debris on the face of the intercooler.

This photo shows the hose leading from the turbocharger, in the upper right hand corner of the photo, down to the hard-pipe crossover in the lower left.
Figure 17

This photo shows the hose leading from the turbocharger, in the upper right hand corner of the photo, down to the hard-pipe crossover in the lower left. The silver diverter valve (see the Diverter Valve project) is connected through a T-connection into this intake hose, just before the air enters the hard pipe. All three hose clamps need to be loosened to remove this hose.

After the hose is removed from the turbocharger, it's easy to see the amount of oil that has collected at the compressor outlet, as well as how it has streaked as the compressed air streams out of the turbo.
Figure 18

After the hose is removed from the turbocharger, it's easy to see the amount of oil that has collected at the compressor outlet, as well as how it has streaked as the compressed air streams out of the turbo. You can also see the turbocharger support bracket, center section oil drain tube, and the wastegate actuator on the right of the photo.

Clean the turbo-side hose with dish soap, water, and a brush.
Figure 19

Clean the turbo-side hose with dish soap, water, and a brush. Do the same for the other hoses you've removed.

Before you clean the intercooler, remove the charge air pressure sensor.
Figure 20

Before you clean the intercooler, remove the charge air pressure sensor. It pops out after you remove these two Phillips-head screws.

The sensor has a coating of oil on it
Figure 21

The sensor has a coating of oil on it - clean this up with a rag before you replace it.

Looking into the intercooler outlet, you can see the end of the intercooler core and how the air passes through it.
Figure 22

Looking into the intercooler outlet, you can see the end of the intercooler core and how the air passes through it. A bit of pooled oil is barely visible at the bottom of the duct.

Tape up the opening for the pressure sensor.
Figure 23

Tape up the opening for the pressure sensor.

Fill up the intercooler with soapy water and let it sit for just a bit so that the soap can go to work on the oil.
Figure 24

Fill up the intercooler with soapy water and let it sit for just a bit so that the soap can go to work on the oil. Cover the inlet and outlet of the intercooler with your hands (use latex gloves or similar) and tilt the intercooler back and forth to move the soapy water around. Rinse and repeat until you're getting clean soapy water out of the intercooler, and then flush it a few times with just water until the soap has been rinsed out. I have read about people using gasoline to clean out an intercooler, but to my mind soap and water works nearly as well and isn't nearly as toxic or hazardous to deal with.

Spray the faces of the intercooler with water to clean them out and remove any debris that has built up.
Figure 25

Spray the faces of the intercooler with water to clean them out and remove any debris that has built up. When you've cleaned the intercooler and hoses entirely, set them in a safe place to dry completely before reinstalling everything. Make sure you drain as much water out of each component as you can before air drying.

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Comments and Suggestions:
daniel Comments: I did notice some oil when removing the tubing from the intercooler and this helps alot how to clean it with out risking damge. On the throttle body is it really necessary to use the throttle body cleaner? I had but an A4 1.8 and the previous owner wasn't that much on point with the small things. Had caked in oil in some pipings. But got it cleaned.
Can it be done easily like Mikey said from top to bottom out.? Also this is not related to this but a good pic or diagram would help for setting up a recirculating oil can or catch can. Thanks
October 26, 2016
  Followup from the Pelican Staff: Wipe the throttle housing down by hand only. No cleaner harsher than soapy water. If using soapy water, remove to clean. - Nick at Pelican Parts  
Mikey Comments: Is it possible to leave the intercooler inplace on the vehicle and clean it while still attached. Pouring in 91% alcohol at the top of the intercooler, let it drain out from the bottom with the help of a blower, and re-attach the hoses except the one to the intake and use the turbo to heat dry it?
October 26, 2016
  Followup from the Pelican Staff: It won't drain correctly. - Nick at Pelican Parts  
Mack Comments: Good day guys. Hope you can help on my Audi A4 B6 1.8T. My cat was clogged and I have gutted it. Car's responsive and faster. But immediately after fitting, my car started having excessive non-stop white smoke. Its not letting away and its not vapour. Additionally, also this smoking started, the turbo seems to be seeping oil when engine runs- leaks where Manifold and turbo connects. It seems to be spraying out. Never happened before. Lastly, I have noticed something strange - the breather pipe leading to the turbo and PCV seems to have water mixed with oil in it. That's the hose leading to the air intake towards the turbo? Could the intercooler be clogged with oil/sludge - causing white smoke?
May 4, 2016
  Followup from the Pelican Staff: White smoke is likely coolant. I would pressure test the cooling system. If the system will not hold pressure and there are no external leaks the head gasket may be faulty.
- Nick at Pelican Parts
 
Ricky Comments: So can it aslo work for an audi a4 2003 1.8t sedan, for some reason i cant see on the description. Thanks
March 18, 2016
  Followup from the Pelican Staff: I don't see it in the vehicle list. But the procedure may be similar.

Applicable Models:



Audi A4 (1997, 1999-01)
Audi A4 Sedan (1998)
Audi A4 Quattro (1997, 1999-01)
Audi A4 Quattro Sedan (1998)
Audi TT (2000-04)
Audi TT Quattro (2000-04)
VW Beetle (1999-02)
VW Golf (2000-02)
VW Jetta (2000, 2002)
VW Jetta Sedan (2001)
VW Passat (1998-00)
- Nick at Pelican Parts
 
ben Comments: Hi , I mistakenly poured excessive oil to the car due to a clogged oil pump strainer that kept sending -low oil pressure fault signal on the cluster. The car has lost power, the intercooler was cleaned,lambda sensors replaced oil replaced,but still no power.Any ideas of what next to do? Kind regards
April 10, 2015
  Followup from the Pelican Staff: The cat may be plugged. Check exhaust back pressure. - Nick at Pelican Parts  
Chrissy S3 Comments: Hey, i've got an Audi S3 1999 APY. Can i use this process ? is the engine build up the same ?

Thanks.
January 11, 2015
  Followup from the Pelican Staff: I don't believe so. This article applies to:

- Nick at Pelican Parts
 
rch Comments: Nick
We have a 2000 Jetta in which we are experiencing periodic problems that cause the CPE check light to come on and then the motor goes into trouble mode reducing travel speed to 35-40 m/h. Back in June of this year we were experiencing the same problem so I replaced the diverter value and the problem was solved. Now it is back. I"m planing on cleaning the intercooler, ducts,and sensor on the intercooler and diverter valve. In hopes that this will solve the problem. Is there any other sensors or other things that may cause this problem. Thanks, for the great article on intercooler cleaning.
rch
December 15, 2014
  Followup from the Pelican Staff: Assuming its a TDI? Check if the vacuum pump is supplying good vacuum and all the ducting is sealed. What fault code is is setting? - Nick at Pelican Parts  
djl680 Comments: I have a 2001 passat 1.8t and my lower intercooler pipe is leaking oil out constantly over the past week does this mean I have bad turbo?
December 5, 2014
  Followup from the Pelican Staff: Is the engine low on oil? If you are using oil and it is leaking out of the intercooler pipe, then likely. - Nick at Pelican Parts  
Sam Comments: I found that one of my pcv hoses was cracked and my intercooler is full of oil. I cleaned my intercooler and replaced the damaged pcv lines. Does my damaged pcv system can cause hood amount of oil in the intercooler? What trouble cause cause an intercooler full of oil? Someone told me that my turbo was pushing the oil with air at high boost in my engine. Is that possible? I have a 2003 jetta 1.8t
November 13, 2014
  Followup from the Pelican Staff: Some oil in the intercooler is normal. I would drive it a bit, and check it again. If it is a small puddle in the elbow of the pipes, don't sweat it. - Nick at Pelican Parts  
traylerpark Comments: l just bought 2001 with 1.8t,told it had new turbo,and coils,it runs like crap,it was only suppose to have rad leak,l changed rad,also waterpump because engine had been froze over winter,where do l start,it runs but go on highway it overheats in about 4 miles of running,need help
April 13, 2014
  Followup from the Pelican Staff: If it overheats, you may have a faulty head gasket. I would pressure test the cooling system, if the system does not hold pressure and there are no external leaks, the head gasket may be faulty. - Nick at Pelican Parts  
driver Comments: help????? hey nick have a big problem with my 99 passat wagon 1.8t have an issue with turbo leaking oil, exhaust issues, loss of power, so I changed the turbo with catalytic converter and downpipe, also cleaned the intercooler with all the hoses with soap and water like you explained and also cleaned the throttle body took it out and cleaned it real good. car turns on but it sounds still rough. like I have an exhaust leak in the front and still have no power. she chokes when I throttle up when I punch it takes a few seconds before it picks up. any ideas ???? had it all apart but forgot to check exhaust manifold
April 11, 2014
  Followup from the Pelican Staff: Have you checked for fault codes? It sounds like you have an engine misfire. I would try to isolate the weak cylinder, then check spark, fuel and compression. - Nick at Pelican Parts  
Adrian Comments: So having oil in my intercooler piping is completely normal, right? But how do I know if I don't have a bad Turbo or a leaking gasket inside the Turbo?

Thanks.
February 24, 2014
  Followup from the Pelican Staff: Some oil is normal, there can be too much which is a sign of a failure. If there is excessive oil, it is likely the seal in the turbo. - Nick at Pelican Parts  
Bobby Comments: What do you think about using acetone or rubbing alcohol to clean the intercooler?
August 20, 2013
  Followup from the Pelican Staff: No, do not use anything like that. When you use caustic cleaners, there will be residue that could get into the engine afterward and create an issue.

If you want to clean it, use dish detergent and warn water. Start at the inlet and clean in the direction of air flow. You can tap or chake it to move dirt around. When done, flush with clean weater. Then dry using low pressure compressed air. Make sure it is dry before reinstalling it. - Nick at Pelican Parts
 

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