First, thanks to all who offered their help. My problem was my 88 245A idled rougher at operating temp than when first started and took a long time to get to operating temp. At first I attributed it to a faulty temp guage. Or a faulty electronic temp sensor. I started with the simpliest fix suggested, the thermostat. Sure enough, the thermostat was in two pieces. Apparently the pressure of the spring expanding and contracting fractured the bracket. It was not the orignal but it did say "Volvo Wahler". The new part from a local parts store just said "Wahler". Cost $10.00. Took 20 minutes to remove and install. Very quick and easy to replace. Engine gets to operating temp quickly and idles well. I learned that there are 4 different temp ranges offered, all listed in Celsius. I opted for the OE range for my climate.