Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

Which Thermostat? [Editor/Bob] While you've got a choice, the Volvo specifications are:
Thermostat: begins to open at:
B 200/204/230F/FD 198º F (92º C)
B 230FTurbo/234 189º F (87º C)
B 6244/6254/6304 195º F (90º C) (changed from 87 for replacement
thermostats)
D24/24T/24TIC 189º F (87º C)
How to Replace. [Top from Mike G.] Even with limited mechanical ability, you should be able to
change a thermostat on the 4 cylinder Volvo (assuming the problem is a stuck thermostat). To
remove you can simply undo the two nuts holding the thermostat cover on top of engine at front,
the one with the big top hose from radiator connected to it. You will lose a little coolant, so have
some new 50/50 ready to go. Remove thermostat with its rubber o-ring, note orientation, so that
you don't put the new one in backwards or upside down (yes it matters; see the photo below).
Put new o-ring on the lip of the new thermostat, put assembly in hole, put cover back on,
tightened nuts snugly but don't tighten with all your might as the studs are in aluminum: tighten
just enough to seal the o-ring. Fill with coolant, start car, check for leaks, check coolant level
after all warmed up. I usually boil the new one before installation to note that 1. it actually opens,
and 2. that it opens at about the correct temperature. Good luck. PS Don't buy a cheap
thermostat at a cheapo supply place; go to a good aftermarket supplier or theVolvo dealer as
they are cheap.
Installation and Troubleshooting Tips. Thermostats must be installed with the small venting
nipple oriented upward. If incorrectly installed, an air pocket will form in the thermostat housing
causing a reduction
of cooling abilities.
When you replace
coolant, loosen the
thermostat housing
when refilling and
bleed air from the
system until the
coolant appears at Thermostat and O-Ring
the thermostat, just
to make sure you
have no air bubbles.
For pitting on the
housing or the head
adjacent to the
thermostat, seal it