Replacing the Diesel Fuel Filter
 

Inspired by gnat this article discusses how to replace the fuel filter on a diesel Cayenne. Diesel fuel systems operate at very high pressures so that any water or dirt that gets to into the fuel system can be very bad and expensive to repair. To protect the fuel system a fairly substantial fuel filter is provided. The filter traps dirt and allows any water to collect at the bottom of the fuel filter housing. On the Cayenne it is located in the engine compartment on the passenger's side as shown below.
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Porsche requires that every 10K miles the fuel filter housing have any water extracted from the bottom of the fuel filter housing and that the filter be replaced every 20K miles. I just replace the fuel filter every 10K miles since the filter has to be removed to extract any water from the fuel filter housing. The Porsche filter used for the diesel is P/N is 958 110 134 10 or its OEM equivalent MANN PU8007 at half the cost. The filter is shown below.
https://cimg5.ibsrv.net/gimg/rennlis...3e989d05a1.jpg

You will need a T20 torx male bit and an inch pound torque wrench to remove and replace the five fuel filter top screws.

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It is nice to have a tool to remove the plastic cover clips.

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You will also need some type of extractor to remove any water from the bottom of the fuel filter housing. I used an oil extractor from my boat.


The steps to replace the fuel filter are roughly as follows:

1. Open the hood, remove the plastic clips on the passenger side cover along with the cover to expose the fuel filter. Also remove the engine cover at this time to give more access to the fuel filter.
   
2. This will be a somewhat messy and smelly project so wrap the fuel filter housing below the top with rags or paper towels before taking the top of the fuel filter off. Also have a zip lock bag nearby for the old fuel filter.
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3. Using the T20 torx bit carefully remove the five screws from the top of the fuel filter housing. Don't drop them into the bowels of the engine bay. Oddly there is a sixth hole in the lid, just ignore it.
   
4. Fold the top of the fuel filter housing out of the way and carefully pull out the old filter and put it in the zip lock bag for disposal.
   https://cimg8.ibsrv.net/gimg/rennlis...4b5cd53ba1.jpg
   
5. Use the extractor of your choice to suck out any water in the bottom of the fuel filter housing.
6. Drop the new filter element into the housing and carefully re-install the five screws into the cover. Torque the screws to 60 inch pounds.
   
7. Start the engine and let it idle for a few minutes to bleed out the air introduced by the installation of the new filter. Check for leaks.
   
8. Re-install the passenger side cover and the engine cover.
   
9. Go for a test drive with one or two wide open throttle openings to ensure all the air is gone.