O-Ring on Coolant Tank? 91 Jetta 1.6 NA

[rs899]

My Jetta project car is pretty much running now, and I decided to address all the coolant issues last weekend and give her a quick citric acid flush last weekend.  I bought new flanges for the head ( they were both cracked by the PO) and a new coolant tank and cap from AZAutohaus since the originals were dirty looking.  This is the newer round style with the level sensor.

Neither the tank nor cap came with an O-ring to seal it.  Is this normal on this design?  I don't think I have seen any in boneyards that had the o-ring either...?

Rick

[fatmobile]

That needs an o-ring.

[Op-Ivy]

There should be an o-ring at the top of the threads on the cap.

[rs899]

At the top of the threads is where I would have expected it, but closer examination of the replacement cap I have indicates that there is an o-ring on the OD of the internal pressure plug that seals against the ID of the tube that goes into the tank.  Some websites have it listed for sale separately as a 28.5mm o-ring and that looks about right.