1990 240, new to a friend, runs hot - needle ~1/8" below red. I'm used to them running ~1/8" under the mid-point dot. I drove around on a hot day: needle drops a bit coming down hills but otherwise high.

- Pulled thermostat. It's broken*. Replaced. Runs almost as hot but needle goes up slightly as speed increases.

- IME above is often sign of a clogged radiator. Ran flush through it. No change.

- Pulled temp compensator board and jumpered. No change.

- Replaced temp guage. Now runs a hairline below the middle.

No reason I can think of that the temp gauge and thermostat failures are unrelated.

However: the fuel gauge was also off: with tank full, needle was at 3/4; when at E dead bottom, there were 5 gallons in the tank. I replaced the fuel gauge and now it works correctly.

*I've seen more broken Volvo brand thermostats than aftermarket but that might just be because they're original.
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240 drivers / parts cars - JH, Ohio