These are the rings that fit inbetween the heat exchanger and the head and must be replaced every time the heat exchanger is removed. please make sure that the old rings are carefully removed by pinching them out rather than using a chisel that could damage the sealing surface. never stack the rings! one per cylinder! 1.7 rings have a slightly smaller interior diameter than the 2.0 variety. Four required.
Known as: sealing ring
This is the copper sealing ring between the heat exchanger and the head for all of the above captioned models. make sure you carefully remove the old seals first and do not use a chisel! seat the heat exchanger and torque the nuts in a "z" pattern. you may also want to replace the exhaust nuts. replace the studs only as necessary.
Known as: sealing ring