just went to dig out my old thermostat from the shed, removed in a big service as was warming up but not reaching mid gauge anymore and if off throttle would actually go cooler again.
anyway was original thermostat since new and is marked behr Italy.
I cant see any sign of temperature of thermostat opening but 88c sounds right to me, 80c seems too cold.
if they ever made 80c ones I bet they were updated to 88c for efficiency or emissions etc.
just tested it in the sink with warm(from tap water) sealed 100% no drips
heated up body and filled with kettle water, opened and drained out.
refilled warm tap water and is again sealed 100%.
can see what looks like might be jiggle pin but could be stuck as sat in shed 12 months.
will see if I can check what temp it opens reliably but tested on car logged ,it opened too early.
and here compared to after new stat
this is old stat / new stat same commute similar weather conditions
ive got to be honest I wasn't expecting a perfect seal in the stat, mine just opened early?
tested in an old pan, started to let water seep past at 78-80c was pretty much well open 82-84 and total distance I saw was approx. 9-10mm travel open to shut(may be more as would get hotter than 100c when pressurised)
the description above was very accurate in how it works, the plate at the far end to blank the heater outlet is also sprung and the distance looked at least 10mm so guessing its gotta get above 100c to travel far enough to blank that port( plate has holes so just restricted not blanked)
probably a safety feature to save cabin heater matrix getting too hot.
also what looks like a wiggle pin isn't, just a dome in the plate
heres a vid (not ideal thermometer for this test, but matched logs), open before 80c
another fully open(as far as it would to fully closed as it air cooled)