Interesting temp gauge question

[Mafiaracers]

Cliff Notes:

1990 325i coupe, auto, 105k
water pump/t-belt/tstat job
block drain (figured why not while I was draining fluid)
re-fill with 2 gal dealer fluid and top-off w/ distilled water
installed dealer w-pump and t-stat
pre-filled all hoses prior to clamping down to respective locations
bled system using bleeder screw, on an incline, using proper method/technique

car came up to temp just as it should, bled just fine. my issue now is the temp needle. It reads exactly 1/8" past vertical (on the hot side) and stays there. Cabin heat is nice and toasty at idle and while driving....Burp it, bleed it, neutral and hold 2500rpm idle, re-circulate on with heat blasted, nothing....stays a hair over vertical. Even driving it, it won't climb or fall...idle, won't climb or fall...just parked on the warm side. Hell, even a temp gun pointed right at the housing shows a healthy 185*

I don't know the temp number on the t-stat I pulled out of the car as isn't long since in the trash and I don't know the number on the dealer t-stat as I didn't bother to look at it.

So, faulty t-stat? should I go find an 80*? Should I get a colder one? has the sensor gone bad? Head gasket is fine as the oil is as clean as ever...

Thoughts?

Thanks!

[dashboardmonkey]

Just over vertical is fine. If it bothers you that much get a colder t-stat.

[jlevie]

A steady state temperature of 185F would correspond to an 85C thermostat. That is acceptable, but a bit too high. Either they gave you the wrong thermostat, or it is defective. I'd change it out for the stock 80C thermostat (176F).