Perkins 4.108

I am about to replace th thermostat in my 4.108. What temp should it be? 180? 160? or?

 

I think this will help
http://www.asap-supplies.com/gasket-for-perkins-4107-and-4108-thermostat-housing

 

I have a perkins 4108 in my Gulfstar 37 I run a 160 thermostat and my engine temp stays between 170 to 175. In really cold water the engine may come down to 165 and in the warm water in Mexico my temp would sometimes get up 180. I have a friend who runs a 180 thermostat in his 4108 and he seems to be forever fighting an overheating engine. The least little blockage anywhere in the cooling system and his 4108 overheats. My original Perkins manual list an operating temperature range of 150 to 200.

 

Diesels run more efficiently at higher temperatures. My 1972 4108 runs a generator at 1800 rpm. With a 180° stat runs 175° unless under a full load and then 180°. With a 160° stat it uses about 5% more fuel. I am rarely in water above 55°.
My Ford F-250 diesel gets 7-8% better economy with a 205° stat opposed to the stock one.

 

Lepke
You may want to check your thermostat because if you have a 180 and the engine rarely gets to 180 your stat is probably stuck partially open. Just a thought after reading your post.