W40 thermostat

[Ed.]

So I'm about to clean fresh water circuit system on W40.. regarding this guy.. (I dont have white carpet tho.. nor engine u can eat from..)
and after few days fighting bolts I've figured there's no thermostat... 
Regarding condition of bolts I believe t-stat is missing for quite a time (years/decades..)..
Is this common practice to remove t-stat from W40?
How bad it's hurting the engine?
(AFAIK I've W40 - "Perkins block 4.107 but uses fresh water pump 108" regarding exowner notes..)
pics/src attached..
Thanks in advance for any inputs!

[S/V Legacy]

Not that I have ever heard of. Just recently replaced my thermostat with an 180 degree unit. Seems to me that the engine would never completely warm up and could cause issues there. I can only imagine at some point the PO must have had a thermostat failure, pulled it and forgot to replace it?

[Ed.]

Hmm.. could be.. I've no idea.. anyway I've ordered one for Perkins 4.107 from parts4engines.com.. but as advised on page I went for 75C.. which they claim should be used for marine..

[Dale Tanski]

I just stumbled upon this thread... 
Marine engines utilize 160 degree thermostats because at 180 degrees deep in the bowels of the engine cooling surfaces, the temperature reaches a point where the salt will begin to crystalize out. The more salt covers the cooling jacket surfaces the more it insulates and the higher the temperature.  It is a vicious circle. 
They run 160 degree T-stats in them so this doesn't happen.  In fresh water of course 180 degree is not a problem.
Dale