Planning on replacing the heater core in my '96 850. I'm looking at some illustrations and I have some questions.

When you remove the heater core, do the pipes that go from the heater core to the firewall "coupling" fitting remain in that fitting?

Does the movement of the heater core, during removal, cause the sealing at the pipe/coupling interface to fail?

Unless you are a glutton for punishment, do NOT remove the piping from the firewall. Just drain the antifreeze from the engine and catch what is left over in a small can when you unplug the lines to the heater core. Having a towel and plastic handy to keep antifreeze from getting on the carpet is a good idea. Of course, you will want to inspect the firewall coupling for leakage.

When the new heater core is re-installed, use new O rings and new antifreeze. The Volvo stuff is expensive from the dealer but you only need one gallon, mixed with distilled water from the grocery store.

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)