I know you changed the thermostat and I am advising you again to change it to a at least 180°F thermostat and to make sure you get 1 that will work correctly with an old Volvo.

I will ONLY use and sell the thermostats I buy from my aftermarket wholesale sources that sell parts for European cars included old Volvos or the ones sold by Volvo.

The brand names are Vernet, Calorstat or Whaler, NONE OF WHICH I HAVE EVER SEEN SOLD AT ANY OF THE MAJOR AUTO PARTS STORE CHAINS LIKE OREILLYS, AUTOZONE OR PEP BOYS.

I have never tried NAPA, but some of the Mom and Pop auto parts stores could order the correct thermostats from the same local aftermarket sources I use.

So after 30 years of owning and then professionally repairing old Volvos, I highly recommend you get the right thermostat.

FYI, the usual problems with the incorrect thermostats are that they sometimes lack the disc at the bottom which is critical to the proper flow once the thermostat opens and the other common problem is the disc is too big and/or doesn't seat properly on the little tube inside the head. The tube needs to blocked off when the engine is warm. When the tube is not blocked off, enough hot water doesn't go through the radiator to be cooled which causes the motor to run hotter.

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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502