Water in Fuel- "Gas" Cap?

[rs899]

I have been running my Jetta for about 15K miles and last week it started sputtering.  Looked at the fuel filter and I was a bit sickened by what I saw.  The top surface was rusty ( I have a Mk1 filter in a MK 1 flange there) and the banjo bolts were rusty as well.  There was quite a bit of cloudy goo in the bottom.  I changed it- seems to run better - duh!  I think I will have to pay attention to that nifty water trap on the Mk1 filter and perhaps drain the tank when it gets low.

I am wondering how the water got in there, and the main suspect is that water seeped in through the tank filler cap.  The surround has a tiny hole in the bottom that was probably blocked ( not lately, but when I salvaged the car it had been sitting for 2 years).  The cap is one of those clutched deals that really doesn't let you crank on it to get a solid seal .

Question is, is there a good reason for the clutch on the filler cap?  I would like to epoxy it or whatever so that I can tighten it securely. 

[wdkingery]

I love to booger things up too!
But it was likely designed to only need to tighter up that much.. I doubt its yer problem.

[R.O.R-2.0]

I love to booger things up too!
But it was likely designed to only need to tighter up that much.. I doubt its yer problem.

water comes in the fuel you buy, and it condensates in the fuel tank when your tank is not completely full..

the fuel cap is NOT where the water is coming from. promise..

[rs899]

^^ I really don't think it is happening anymore on this car, but when I salvaged it the port back there was plugged up with leaves and compost and it is likely water drained into the tank.  I had some fuel problems early on and I think my recent issues were caused by running the tank lower than I had previously.

On the pickup, the cap is a very solid metal affair that positively seals.  Never had a problem with that ( though I often forget to drain the bottom of its filter as well.)

[BigVWman]

I had one that had the vent tube that follows the filler neck in the wheelwell rubbed through from a tire rub at some point allowing water to get in while driving in the rain, couldn't hurt to check!