Hi doing my coolant pipes and trying to figure out what this single o ring is for? If it's supposed to go in before I put the coupler on the larger single pipe woundnt I need one for each side? It says only one for quantity so I must be mistaken where it goes. My picture is with couple installed with the two factory o rings attached. Just wondering if I'm supposed to put the black one in first then push coupler on but then I should of received one for the other end if I'm right any help this is the ecs kit.

 

It has grooves in it right? I believe the orings go into the grooves if we are talking about the same part.

 

Yeah that piece had grooves and there were o rings on it. I ended up putting it in the thermostat housing side first before I stuck the big pipe in. It felt loose if I didn't put the o ring in first

 

Follow these instructions.
http://bd8ba3c866c8cbc330ab-7b26c6f3..._Upgrade_2.pdf

 

Yeah I'm using there instructions but says nothing about that single o ring and it came with two thermostat housing gaskets.