Thermostat

[88 206]

I have a 1988 5.7 mercruiser, new rebuilt long block running an Edelbrock carb, does anyone know if I should be running an 160 or 140 thermostat? I currently have a 160 in it and according to the indash guage, at idle in lake I am seeing appx 180, new pump housing and impellar at time of engine job. on plane, stays right at 165 mark. I am trying to get my hands on an ir gun to check guage accuracy, but even when guage reads 180 I can put my hands on risers, all hoses and the tops of the risers are hot, but not so hot that I can't keep my hands there. It does seem to rise fairly quickly when I come off plane from 165 to the 180 mark. Thanks for any help in advance. Matt

 

[tfret]

Re: Thermostat

I have the same engine but 1984 model. I switched to the 160 degree and have similar readings. I get better fuel economy than when I had the 140 degree Tstat. If you only run in fresh water like me, I think you're fine.

 

[lcmains1]

Re: Thermostat

Should be running a 140. If you run a 160 you have a chance of running hot and that can cause dieseling.

 

[88 206]

Re: Thermostat

Thanks, I guess I'll change to a 140 this weekend at the lake. lcmains, I see you have a 206, I have A 88 206 Captiva.