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Replacing Crankcase Breather Hoses
 
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Pelican Technical Article:

Replacing Crankcase Breather Hoses

Jared Fenton

Time:

1 hour1 hr

Tab:

$25 to $200

Talent:

*

Tools:

Pliers

Applicable Models:

Porsche 955 Cayenne (2004-10)
Porsche 955 Cayenne GTS (2008-10)
Porsche 955 Cayenne S (2003-10)
Porsche 955 Cayenne Turbo (2003-10)
Porsche 955 Cayenne Turbo S (2006-10)

Parts Required:

New breather hoses.

Hot Tip:

Be gentle removing the hoses.

Performance Gain:

Smoother running engine

Complementary Modification:

Test air-oil separator

One thing I have found on a few Cayennes is an annoying miss or occasional drop in engine speed while idling. This usually ends up being a cracked breather hose leading to the air-oil separator. On our own project car, I noticed that the engine would not idle at all after running perfectly a day or two before. After a quick inspection, I noticed that the line leading from the intake manifold to the air-oil separator had split requiring replacement.

It's not uncommon to have these plastic lines crack after years of heat cycling in the engine compartment. This typically results in very rough running at idle. Additionally, the air-oil separator will not function due to the loss of vacuum. Over time, this can result in problems when trying to get the car to pass an emissions test.

The good news is that the hoses are easy to replace however they can be a bit expensive. Begin by removing the engine covers on the front of the engine. See our article on Removing Engine Covers for more information. You may also find it easier to inspect and remove the hoses with the throttle body removed from the engine. See our article on Throttle Body Cleaning for more information.

Shown here is the common culprit, one of the breather hoses is broken in half (green arrow).
Figure 1

Shown here is the common culprit, one of the breather hoses is broken in half (green arrow). This usually results in a very poor idle and a non-functioning air-oil separator.

Remove the air hose connection from the left valve cover (green arrow) and also open up the plastic clamp holding the air line to the right side valve cover (yellow arrow).
Figure 2

Remove the air hose connection from the left valve cover (green arrow) and also open up the plastic clamp holding the air line to the right side valve cover (yellow arrow).

Now remove the air hose connection from the right valve cover.
Figure 3

Now remove the air hose connection from the right valve cover. Remove the hose connection by pressing the thick, ribbed tabs on either side of the connection (green arrow) and pulling it up and off the port.

Squeeze the tabs (green arrows) on the breather hose leading to the air-oil separator and pull it off.
Figure 4

Squeeze the tabs (green arrows) on the breather hose leading to the air-oil separator and pull it off.

Now remove the air hose connection to the port on the top of the intake manifold (blue arrow).
Figure 5

Now remove the air hose connection to the port on the top of the intake manifold (blue arrow). Also take the time to inspect the rubber (green arrow) and plastic (yellow arrow) hard lines connecting to the intake manifold. Replace them if there are any cracks. At this point, just pop the new hoses into the connections, reattach the throttle body and you're good to go.

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Comments and Suggestions:
V Comments: Hi, I have a 2005 Porsche Cayenne S. I recently changed the starter on the car because it would get stuck and make a screeching sound when I start it. While in process I was told to change the intake manifold gaskets so I did that. The crankcase breather hose cracked when I took them out and had them replaced with temporary rubber hose. When I finally started the car it felt very shaky, it felt as it would turn off any second, I was still able to run it but it was just shaky the whole time so I stopped driving. I figured it had something to do with the crankcase breather hose. So I finally bought the original crankcase breather hose and installed them. However, when I turn on the car it still feels shaky when its still, but when it runs over 50mph, I don't feel it as much. Any thoughts/advise/ideas of what the problem may be? I didn't have that problem before I changed the starter or the manifold gaskets or the crankcase breather hose valve to valve and the hose to the intake
July 26, 2016
  Followup from the Pelican Staff: The main problem being a screech when starting? That could be too tight of fit for the starter gear.- Nick at Pelican Parts  
cross Comments: My 2005 Turbo has a second thin hose that runs to the back of the engine. I'm assuming that I have to take off the manifold to get back there. Is that correct?
April 12, 2015
  Followup from the Pelican Staff: No, the turbo breather hose job can be done without removing the manifold BUT is MUCH MUCH easier if you do remove the manifold. - Casey at Pelican Parts  

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