5.7 operating temperature

[madmaxum]

While having my boat winterized the mechanic recomende that I replace my thermostat, water circulation pump and risers on my 1997 Maxum 5.7L.The boat has about 400 hours on it. Last season the boat ran at 175 degrees while cruising. When slowing down the temp would drop. I have had it out 3 times this season and it still runs at the same temperature even with all of those items being replaced. This is my second season with the boat. I have read numerous posts about how these engines should run between 145-160 degrees. My mechanic says not to worry. Should I be concerned?

 

[Don S]

Re: 5.7 operating temperature

Your mechanic is right, don't worry. When the engine is under a heavy load (up on plane and running) the temp will rise, it's very normal and 175° is also normal, even with a 142° thermostat.

 

[Haut Medoc]

Re: 5.7 operating temperature

You don't say wheather you have a closed system, or are fresh water cooled. 175 is a little warm, but not overly so, and within limits. However, if it gets above 180+, I would say something is up.

 

[magster65]

Re: 5.7 operating temperature

The maximum thermal efficiency of a gas engine is at an operating temperature of near 200. With a 'closed system' or FWC there is no problem running a 180 thermosthat and the temperature shouldn't change much from the 180 (the thermosthat will open more). The problem is mainly from running in salt water where salt collects in the 'nooks and crannies' of the block when it gets hot. Therefor an 'open system' or RWC must run at a lower temperature even though it's not ideal.

 

[madmaxum]

Re: 5.7 operating temperature

thanks for the responses, it is raw water cooled