viscous fan clutch play

[EdwardBernard]

On my 230 SL I noted that there is a small degree of "wobble" or play (less than 1 centimetre) when I move my metal fan blades front-to-rear, which makes me suspicious of the fan clutch. My water pump is new. The engine has not been run, so I can't assess the fan clutch's behaviour at idle. I have not yet installed my radiator, so if I need to replace the fan clutch, this is the best time to hear any bad news.

   I also read in some spots that the 230 SL M127 engine didn't have a fan clutch-- true? My set-up is definitely with a fan clutch and five-blade metal fan. Thanks for any insights...

[Nicolas Aristodemou]

Yes the 230SL is supposed to have a four bladed fan without a viscous coupling. The 250 and 280 SLs have the six bladed fan with a viscous coupling. See attached photos. So having a 5 bladed fan with a viscous coupling on a 230 SL  (M127 engine) is definitely non standard. As for the play that you are experiencing, if the water pump is new and the fan/coupling screws are tight it can be nothing else that a defective viscous coupling.

[66andBlue]

Perhaps non-standard in the strictest sense of the word but you could request a water pump for a viscous clutch as a SA.
My 1966 230SL came that way.

[wayne R]

Edward,  i know with my years on other brands, mainly GM, a viscous fan clutch at about  70degress temperature,
cold engine, by spinning with your hand,  fan should not spin more than  one and quarter  to one and a half times.
and should not half any play in bearing.

[EdwardBernard]

Thank you both! I appreciate your expertise.