2010 Audi A3 TDI
I just replaced the fuel filter, VW 3C0 127 177 with a Mann PU-825-X and it leaks. I put in the new O-ring, carefully. I was extra, extra careful as I tightened down the lid to the filter housing. I hand tightened the torx bolts in a star pattern so I wouldn't warp it, but it still leaks. So I put the old fuel filter back in, figuring the filter might be incorrect, but leaks too.
I know that the lid doesn't have a gasket but I am thinking that might take car of the leak, but it is a band-aid fix.
Mine was the single hole type of filter. I was rather paranoid doing this so it wouldn't leak. I tightened the bolts down in a star pattern in an incremental manner so the lid would seat properly.
The O-ring I double checked to make sure it was not twisted and sat properly.
I went back in and put back the original filter and it leaked, so I don't know what gives.
I wonder if it is possible to apply a gasket between the two metals to make a perfect seal against this leak?
I wonder if anyone has done this mod. before?
I hate to haveto go to the ******* for this rather simple DIY. Apparently it is not so simple, at least for me.


Old filter on right, Mann filter on left.
Any ideas?


filter.jpg