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Audi A4 Crankcase Ventilation and EGR Hoses and Valve Replacement
 
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Pelican Technical Article:

Audi A4 Crankcase Ventilation and EGR Hoses and Valve Replacement

Steve Vernon

Time:

1-6 hours

Tab:

$1 to $200

Talent:

****

Tools:

Pliers, screwdriver, sharp knife

Applicable Models:

Audi A4 1.8 T (2002-08)

Parts Required:

New hoses and valve

Hot Tip:

Use caution working with old hoses

Performance Gain:

Car runs like normal again

Complementary Modification:

Replace vacuum hoses

The Audi A4, like most modern cars, runs with very strict regulations on pollutants while still trying to get every mile per gallon it can from fuel. The engine is designed to use the vacuum pressure created by the pistons to assist in the fuel injection, turbo and emission systems.

If the vacuum system starts failing, you can have problems ranging from a rough running engine, poor mileage to failing a SMOG test. While this article is not meant as a complete breakdown of the design and implementation of the engine and its vacuum related components, it is more of a guide to point out the hose, valves and fasteners used to keep the system running correctly. When trouble shooting the system, a pressurized test is really the only way to verify minor leaks, but you can check each hose and connection for trouble. With the hoses look for dried, cracked or split hoses. Hoses with bulges are failing and should be replaced. Hoses that are cracked or drying out should also be replaced. A hose should be soft to the touch and easily compress when squeezed and then spring back out to its original shape.

There are a series of hoses and a valve making up the vacuum and emission systems on the vehicle.
Figure 1

There are a series of hoses and a valve making up the vacuum and emission systems on the vehicle. The main areas to check are above the intake air cleaner (red arrow), to the right side of the rear of the engine cover (yellow arrow), and to the rear of the intake manifold (green arrow) and the intake manifold itself.

The area to the rear of the intake air box contains the EVAP valve (red arrow) and lines (yellow arrow).
Figure 2

The area to the rear of the intake air box contains the EVAP valve (red arrow) and lines (yellow arrow). If the EVAP valve is throwing an error code, it is best to just replace it. The lines should be checked for condition and replaced as needed. The hose clamps used from the factory need a special tool to reuse. Most people just pry the clamp off with a screwdriver and replace the clamp with a standard hose clamp.

In front of and below the intake air box is the secondary air pump (red arrow).
Figure 3

In front of and below the intake air box is the secondary air pump (red arrow). There are two plastic lines that will split when cracked.

The secondary air pumps intake line connects to the air box (red arrow).
Figure 4

The secondary air pumps intake line connects to the air box (red arrow). The output line connects to the combi-valve (yellow arrow).

At the rear of the engine you will find the combi-valve (red arrow) and s series of hoses and valves for the EGR system (yellow arrow).
Figure 5

At the rear of the engine you will find the combi-valve (red arrow) and s series of hoses and valves for the EGR system (yellow arrow). The lines should be checked for condition and replaced as needed. The hose clamps used from the factory need a special tool to reuse. Most people just pry the clamp off with a screwdriver and replace the clamp with a standard hose clamp.

The intake manifold has a series of vacuum and EGR hoses attached to it.
Figure 6

The intake manifold has a series of vacuum and EGR hoses attached to it. On the rear is a line that connects to the EGR system. Like most of the hoses, it came from the factory with a clamp that is very difficult to reuse (red arrow). If you are ordering new hoses you should also be getting new clamps to be on the safe side.

There is a vacuum line on the right side of the manifold (red arrow).
Figure 7

There is a vacuum line on the right side of the manifold (red arrow). This hose has been worked on before and already had the clamp replaced.

While the gasket that seals the crankcase ventilation valve is not as critical as a fuel seal, it is always a good idea to replace it (red arrow).
Figure 8

While the gasket that seals the crankcase ventilation valve is not as critical as a fuel seal, it is always a good idea to replace it (red arrow). These gaskets get old and dry up and leak over time.

With the intake manifold removed you can see the crankcase breather hose (red arrow) and the turbocharger recirculating valve (yellow arrow) and the secondary air injector solenoid (green arrow).
Figure 9

With the intake manifold removed you can see the crankcase breather hose (red arrow) and the turbocharger recirculating valve (yellow arrow) and the secondary air injector solenoid (green arrow). The lines should be checked for condition and replaced as needed. The hose clamps used from the factory need a special tool to reuse. Most people just pry the clamp off with a screwdriver and replace the clamp with a standard hose clamp. These hoses and valves are all mounted below the intake manifold and cannot be serviced without first removing the manifold.

While the clamp that seals the crankcase ventilation valve is not as critical as a fuel seal, it is always a good idea to replace it (red arrow).
Figure 10

While the clamp that seals the crankcase ventilation valve is not as critical as a fuel seal, it is always a good idea to replace it (red arrow). This hose gets old and dry ups and leaks over time.

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Comments and Suggestions:
Matthew Comments: Hi I'd like to order the hose for the EGR system, but I can't find it on your website
March 30, 2016
  Followup from the Pelican Staff: You didn't mention what vehicle you have. For an instant response, give our parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need. - Nick at Pelican Parts  

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