There is also a note on fixing the common oil leak coming from the valve cover breather hose. The leak is from oil mist settling at the bottom. The top of the hose has a clamp but the bottom doesn't. This oil mist is from the high diesel compression and piston blow by and the running engine. The reason it's piped back into the air intake hose is so that it's burned and not released into the open atmosphere for emissions and cleaner road surfaces and groundwater.
(optional and helpful) spring clamp pliers
regular replacement air filter for 2.0L BHW VW Passat TDI: VW# 058 133 843
cold climate air filter VW# 8d0 133 843
Note - I'm not sure if the cold climate air filter can fit the regular air box. If you find out either way, please take a picture and post it in the myturbodiesel.com forums to let others know. The difference should be a foam pre filter for keeping snow from soaking the paper filter.
Use the phillips screwdriver to remove the 2x screws on top of the air filter
box holding the decorative plastic cover (already removed in the below picture) and the 3x screws
on the air intake snorkel (outlined in green). The 2 hard plastic sections
are separate from the middle accordion-like section. After removing the
screws, just pull it up and apart.
Loosen the large hose clamp and the MAF plug. The MAF clip has a small tab lock - gently pry the tab lock up before pulling the plug up. Sometimes the hook in the tab gets stuck so try pushing the plug down while prying the lock to help release it. Then the plug should come up easier.
I prefer to remove the entire box since it's easier to remove the top and get
a good seal on the new Passat TDI air filter. It also lets you clean the
housing of dirt and leaves. To remove the housing, remove the 10mm bolt
and unclip the wires near the front. The wire/clip location is the white
arrow in the next picture, bumper removed for illustration)
Fixing the oil leak on Passat TDI
The valve cover breather hose tends to leak oil at the bottom. This is indicated with a yellow arrow below. You don't have to remove the front bumper, it's just for illustration.
To fix it, first release the hose
clamp at the top of the valve cover and pull the hose off. Clean off any
oil and put a light smear of gasketmaker around the bottom barbs. Then
reinstall the hose with a hose clamp. This should stop any oil from leaking out and streaking all over the bottom of the car. While you're in there, also make sure the large air tube's
hose clamps are secure.
Below is the air filter box after removal (the large intake hose was attached, this is not required). To split it open, pop open the 4 metal clamps around the edge. The air filter sits inside this box. Clean out any dust on the housing and reinstall. The bottom has 2 pegs which attach into the frame rail. Also note the heat shield placement.
Installation is the reverse of removal.
If you have any questions about replacing the air filter for the engine on your 2004 or 2005 Volkswagen Passat TDI with 2.0 BHW engine or see a broken link or picture, please report it in the mk4 VW Passat TDI forums, thank you!