Leaking Diesel Fuel from bottom of fuel filter housing

MY1STVW

Well-known member
Joined
Jun 15, 2004
Location
Lee's Summit, MO
TDI
Passat TDI Wagon 2004
Does anyone know why I'm leaking diesel fuel from the bottom of my fuel filter. I remove my belly pan and noticed fuel on the pan. Removed the top engine cover and felt the bottom of the fuel filter and it was wet. Is this the drain port on the bottom leaking??
 

DickSilver

Veteran Member
Joined
Jun 6, 2004
Location
Kentucky
TDI
2004 B5.5V, 1996 B4V
The drain port loosens by unscrewing it, so try tightening. It has normal right-hand threads, but it is the devil to get at when the filter is in the car. Don't get murderous while twisting it: it is just nylon or some other plastic.

If it still drips, buy a new filter & install. There is a how-to thread if you need it.
 

MY1STVW

Well-known member
Joined
Jun 15, 2004
Location
Lee's Summit, MO
TDI
Passat TDI Wagon 2004
Okay I found the leak with your help DickSilver. The center dimple in the white plastic cap on the bottom of the fuel filter housing is cracked. I tighten the white plastic cap just a bit with my fingers and had someone key on the ignition to energize the fuel pump and found the leak in the cap itself. Does this white cap come with a new filter or do I have to order a new cap?
 

owr084

Top Post Dawg
Joined
Oct 20, 2004
Location
Northern Virginia (NoVA)
TDI
Passat GLS, 2005, Stonehenge Gray
The "white cap" is the drain valve to remove water from the filter. To be honest, I have never needed to use it. A new filter has a new drain valve.
 

Honeydew

Top Post Dawg
Joined
Nov 28, 2006
Location
Florida
TDI
13 Passat DSG
This past weekend a local member told me about his recent experience with the same issue. He surmised he had previously tightened the drain to much because he took the drain off and found the sealing o-ring split. Since the filter was relatively new he replaced the o-ring which fixed the leaking drain.
 

auntulna

Veteran Member
Joined
Mar 13, 2005
Location
Springfield, MO
TDI
05 GLS Passat wagon, mit panzer plate
This just happened to me too, last week. Dripping from the bottom even though the valve was tight. It was a Mehl, replaced it with a Hengst. Go Hengst!
 

DickSilver

Veteran Member
Joined
Jun 6, 2004
Location
Kentucky
TDI
2004 B5.5V, 1996 B4V
I would be just as happy if there was an optional filter with NO drain valve. There is almost no water in our fuel anymore anyway. Changing the fuel filter every 40K (20K seems anal-retentive to me) has always been good enough; never opened any drain valve.
 

Alchemy

Veteran Member
Joined
Jan 22, 2000
Location
N/A
TDI
None thanks to dieselgate
Dirt is the issue.

I have had three instances where a dirty fuel filter has caused a stumbling problem, once it was so bad the car went into limp mode. Each time, changing the filter made the issue go away (Confirmed on the old filters each time that there was no water in the filter). I drive 25k miles per year and replace the filter every November before the cold weather hits and I always keep one on the shelf in case.


I would be just as happy if there was an optional filter with NO drain valve. There is almost no water in our fuel anymore anyway. Changing the fuel filter every 40K (20K seems anal-retentive to me) has always been good enough; never opened any drain valve.
 
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