New-Old guy to the forum. Thermostat temp question

[motorhead]

I am working on a un-restored 1966 230SL This guys parents bought it brand new in '66. I am going to do the citric acid cooling system flush and want to replace the thermostat. The son that owns it now(71 yrs old) says the engine runs at about 180 degrees. It has the mechanical pump fuel injection. There seems to be three different temperature thermostats listed for these cars. I realize it needs the proper temp to keep the FI mixture right. So which degree "C" does it take? 87c, 79c 67c? Thanks

[Rolf-Dieter ✝︎]

You should have and install a 79c ... also the 180 Temp is quite normal unless it climes above that. Check the fan clutch and make sure it works okay.

[Garry]

230SL,  Not sure they had fan clutch at that point, I think it was just the plastic/nylon 4 blade fan belt driven?

Garry

[motorhead]

Thanks.. This is a non A/C car. I think it has a direct drive cooling fan. No clutch.  Did the 230SL ever come with carburetors or were they ALL mechanical fuel injected?

[Garry]

All fuel injected for the whole series.

[wwheeler]

I think there is also of 75*C thermostat. Which one to use also depends on where you live. In CA, perhaps the 79*C (174*F) is fine. In Texas, I have used the 75*C (167*F). With a completely revamped cooling system, it runs perfectly when it is 80*F and above. By above I mean to frequently 100*F. Around 60*F and below, seems to run a bit cool. I may install the 79*C and see what happens. Local expert say to stay with the 75*C.