While working on a 1994 turbo 850, we have come across a problem installing the top heater core hose. There are two plastic washers (retainers) and the rubber o-ring. What is the sequence of installation for these parts and are there any tricks in installing the hose?

On my hoses I found 2 rubber washers, 2 plastic washers, the yellow or green retainer and 1 spacer. I replaced the hoses and they came with all new parts that were definitely different from the originals, as well as a sketch showing the order. This was from europartsdirect.

Per the sketch, after removing the hose you need to reach in with a blunt pick or something to ensure you have removed all the old washers, spacers, etc. that may be retained in the bulkhead (firewall) fitting.

If you are reinstalling the original hose and did not keep track of the order of parts, why not remove the other hose, note down the arrangement, and duplicate that for the top hose?

With the order of parts in my sketch I just pushed the hoses in till they clicked (only moderately firm). There was no leak afterward. I think if the parts aren't in the right order you will most likely have a loose hose or one which will not click in at all.

If I still have the sketch I will repost with the order on it.