Why So Cool

[Reel Poor]

Why do marine manufactures run their engines so cool. What determins the difference 142deg, 160deg, why not 180 or even 195? Not that i want my engine room that hot. Just wandering whats their reasoning.

 

[Don S]

Re: Why So Cool

Most engines with a 160° thermostat will run at about 175° to 180° when under load. The higher thermostats will run the engine too hot for being in the enclosed engine compartment in a boat.<br />The lower 142° stats are used in salt or brackish water to keep the salt and mineral buildup to a minimum, which also cuts down on corrosion on the cast iron block, manifolds and risers.

 

[trog100]

Re: Why So Cool

i think its bsed on the corrosion factor.. the hotter the engine runs the quicker it corrodes hence the apparently "too low" running temperatures..<br /><br />there is one other factor i think involved.. ideally nothing in the engine compartment gets hotter than half the flash point of gasolene which i think is aound 280 degrees or so.. which is why all this manifold rusting out problem thats been so heavily discussed recently happens.. having to pump raw water around the exhaust parts to keep em down to the same kinda temperature as the rest of the engine..<br /><br />i think u can take your engine temps up a bit without major problems but just bear in mind it might rust out quicker..<br /><br />what i have said is just theory.. buggered if i know for real what 20 or so degrees means as regards quicker rusting.. in reality not much i would recon.. i think its just boats makers working on the safe side.. he he<br /><br />trog100<br /><br />ps.. my four cylinder merc runs at a steady 140 degrees which i think is what the manual says it should run at.. if my car ran down there i would think i was doing it damage to be honest.. in other words its running to cool to burn off acids... water and all the other crap that gets created during the combustion proccess.. still i do worry about the thing rusting away externally which is why i leave it there..