Just posting as a 1986 SVO owner, I kinda went thru all this on my 2.3T some 5 years or so back....from what I gather from your post, could be several things, first off, I've never been big on
radiator flushing,swapping coolant every couple years should eliminate the need for flushing because you think you've went to the point of needing a flushing.....remember
radiators are about $125. or used to be....second off, If you have never changed the coolant sender, change it, it's not so much the mileage on it as is the years might be getting to it.....last but not least, your controller mounted inside under the steering column may be starting to act out, I've seen this more often on cars that live down south in the humid soup......and that inside controller is getting harder and harder to find, if you don't have a extra one and plan on keeping that T.C. for a while better get looking for one...............Long story short, a couple years ago on my '86 SVO with 26k on it, I replaced the
radiator, the thermostat(192), the coolant
sending unit, and the controller inside(think I got that from
NAPA) BUT now she works like new, Ive been very happy.......hope this SVO owner has been helpful in some manner.......OH, I've owned my SVO since 1989......................
