Diagnosing shank stank

[Froyd]

I cannot get rid of a strange metallic smell/taste in the first 3-4oz of any beer that comes out of my taps. Here is what I've done to solve/diagnose the problem:

- Replaced my old Perlick 650ss (known to cause sulfur smells in high acidity beer) with 2019 versions of teh same (supposed to have the smell issues cured)
- Replaced my elbow shank with a version that claimed to be 303ss and 304ss on the elbow part
- inspected my liquid line tubing and found it to be spotless
- I religiously keep my beer line clean with BLC circulated via pump every time I finish a keg
- Sometimes StarSan goes through my beer line if I'm purging a keg that had some left at the bottom

Yesterday, I took a magnet and put it on the shank. Most of the shank was non-magnetic, but the bent tube attracted the magnet. Does the magnetism indicate that the bent tube could not be 304ss or does that grade of stainless have some magnetic property?

Do I need a new shank?

I'm tired of throwing away beer every time I grab a pint!

 

[Cavpilot2000]

Pull off all the offending metal parts and give them a good wash in hot PBW.
I had metallic flavors from my kegerator when I first installed it using stainless faucets and ball lock QDs. TUrns out there was residue from the manufacturing process. All new SS should be cleaned in hot PBW (BLC and sanitizer is not enough) to remove manufacturing residue like cutting oil.

 

[RPh_Guy]

What type of lines are you using? I'm thinking it's just oxidized from sitting in an oxygen-permeable line.

 

[Froyd]

I don't think that's likely because the beer acquires the off taste within 30-45 mins of sitting in the line. My beer line is does not have an o2 barrier, but it's clear food-grade vinyl with fairly thick (1/8"?) walls. I'd be surprised if beer oxidized that quickly in that kind of tubing.

 

[Froyd]

Will try that. The faucets were cleaned with oxiclean free when bough, same with the shank, but after that it's been BLC CIP with the occasional faucet disassembly and brush scrub.

Any thoughts about the shank attracting magnets? could the flavor be due to stainless steel that's not high grade?

 

[RPh_Guy]

You're right, it shouldn't oxidize in a half hour.

If you're worried about the stainless, the obvious thing to do is passivate it (after cleaning).
4% citric acid at >140°F for 2 hours would provide maximal efficacy.