I'm putting a new thermostat in my 84 944. The Vertex and Performance catalogs show the thermostat going in first, then the O-ring, then the metal spacer, finally the retaining ring. The Haynes manual seems to have the O-ring going in first, then the thermostat, finally the retaining ring. No mention of the metal spacer. Obviously, I only want to do this once, because that retaining ring is a son-of-a-gun. Thanks.

 

There is another seal inside the housing that the thermostat pushes against, might want to check it for wear. The O-ring will slip on the outer edge of the thermostat (it has a groove in the middle of it), then:

thermostat with the o-ring installed
shim if needed
snap ring.

 

Thanks for the response. The inner seal is okay, it's a new pump. The old thermostat had the rubber seal that wraps around the edge, but the new one came with an old fashioned O-ring that has to go on either side of the thermostat, hence my question.

 

It should go inside the thermostat ie. O-Ring, thermostat, shim, snap ring.